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CHEMISTRY
FORM 1 NOTES

SIMPLIFIED VERSION
OF CHEMISTRY
REVISION

CLASS NOTES

INTRODUCTION TO CHEMISTRY
Chemistry is a branch of Science
...
The branch of science that study living things is called Biology
...
Physical
Science is made up of:
(i)
Physics- the study of matter in relation to energy
(ii)
Chemistry- the study of the composition of matter
...

Basic Chemistry involves studying:
(a) STATES/PHASES OF MATTER
Matter is anything that has weight/mass and occupies space/volume
...

(i) Solid-e
...
soil, sand, copper metal, bucket, ice
...
g
...

(iii)
gas- e
...
Oxygen, Nitrogen ,Water vapour
...
It thus has a
definite/fixed shape and fixed/definite volume /occupies definite space
...

A liquid is made up of particles which have some degree of freedom
...
It takes the shape of the container it is put
...

A gas is made up of particles free from each other
...
It
takes the shape of the container it is put
...

(B) SEPARATION OF MIXTURE
A mixture is a combination of two or more substances that can be separated by
physical means
...
e
...
sorting maize from maize beans mixture
...
e
...
Decanting water forms sand
...

iv) Skimming-this involve scooping floating particles
...
g
...
E
...
Iron, gold, silver, copper
...

Non-metals are dull, not ductile (do not form wires), not malleable (do not form sheet)
and break on coiling/brittle
...
g
...

(D) CONDUCTORS AND NON-CONDUCTORS
A conductor is a solid that allow electric current to pass through
...

All metals conduct electricity
...

(E) DRUGS
A drug is a natural or synthetic/man-made substance that when taken changes/alter the
body functioning
...
Medicines
are thus drugs intended to correct abnormal body functions
...

A prescription is a medical instruction to a patient/sick on the correct type of medicine
to take and period/time between one intake to the other
...
This is called treatment
...
Prescription and dosage of drugs/medicine to the sick use medical language
...

(ii) 1 x 2 ; means “1” tablets for solid drugs/spoonfuls for liquid drugs taken
“2” times for a duration of one day/24 hours and then repeated and continued until all
the drug given is finished
...
They are called Over The Counter (OTC) drugs
...

All medicine requires correct intake dosage
...
Some drugs are used for other purposes
other than that intended
...

Drug abuse is when a drug is intentionally used to alter the normal functioning of the
body
...
The victim lack both mental and physical coordination
...
They include heroin,
cocaine, bhang, Mandrax and morphine
...


THE ROLE OF CHEMISTRY IN SOCIETY

(a) Chemistry is used in the following:
(i) Washing/cleaning with soap:
Washing/cleaning is a chemical process that involves interaction of water, soap
and dirt so as to remove the dirt from a garment
...
The formation and growth of cells involve
chemical processes in living things using carbohydrates, proteins and vitamins
...

(iv) Medicine:
Discovery, test, prescription and dosage of drugs to be used for medicinal purposes
require advanced understanding of chemistry (v) Fractional distillation of crude oil:
Crude oil is fractional distilled to useful portions like petrol, diesel, kerosene by
applying chemistry
...
Advanced understanding of the chemical processes involved
is a requirement
...

If the body is not functioning normally, it is said to be sick/ill
...

(b) The following career fields require Chemistry as one of subject areas of
advanced/specialized study:
(i) Chemical engineering/chemical engineer

(ii) Veterinary medicine/Veterinary doctor
(iii) Medicine/Medical doctor/pharmacist/nurse
(iv) Beauty/Beautician
(v) Teaching/Chemistry teacher
...

The room is better ventilated than normal classroom
...
A school chemistry laboratory has a qualified professional whose called
Laboratory technician/assistant
...
A school chemistry laboratory has
chemicals and apparatus
...
All chemical are thus labeled
as they are
...

All Chemicals which are not labeled should never be used
...

Care should always be taken when handling any chemical which have any of the above
characteristic properties
...

(ii) Do not try unauthorized experiments
...

(iii) Do not taste any chemical in the laboratory
...

(iv) Waft gas fumes to your nose with your palm
...
They may be highly poisonous/toxic
...
Boiling liquids spurt out portions of the hot liquid
...

5

(vi) Wash with lots of water any skin contact with chemicals immediately
...

(vii) Read and follow safety instruction
...

(viii )Clean your laboratory work station after use
...

(ix) In case of fire, remain calm, switch of the source of fuel-gas tap
...
Use fire extinguishers near the chemistry
laboratory to put of medium fires
...

(x) Do not carry unauthorized item from a chemistry laboratory
...
The conventional apparator used in performing scientific experiments is
called standard apparator/apparatus
...
An improvised apparator/apparatus is one used in performing a
scientific experiment for a standard apparator/apparatus
...

(iv) Glass is comparatively unreactive to many chemicals
...
Measuring cylinder
Measuring cylinders are apparatus used to measure volume of liquid/ solutions
...
Measuring
cylinders are named according to the maximum calibrated/graduated volume e
...

“10ml” measuring cylinder is can hold maximum calibrated/graduated volume of
“10mililitres” /“10 cubic centimetres”
“50ml” measuring cylinder is can hold maximum calibrated/graduated volume of
“50mililitres” /“50 cubic centimetres”
“250ml” measuring cylinder is can hold maximum calibrated/graduated volume
of “250mililitres” /“250 cubic centimetres”
“1000ml” measuring cylinder is can hold maximum calibrated/graduated volume
of “1000mililitres” /“1000 cubic centimetres”
2
...
It must be clamped first on a stand before being used
...
They are calibrated/ graduated to run out
small volume required to the maximum 50ml/50cm3
...
This
ensure the amount run out from a tap below can be determined directly from burette
reading before and after during volumetric analysis
...

3
...
It is open on
either ends
...

To fill a pipette to this mark, the user must suck up a liquid solution upto a level above
the mark then adjust to the mark using a finger
...


(ii) Pipette filler
Pipette filler is used to suck in a liquid solution into a pipette instead of using the
mouth
...

This requires practice
...
Volumetric flask
...
It is used to measure
very accurate/exact volumes of a liquid solution
...

Volumetric flasks are named according to the maximum calibrated/graduated volume
e
...

“250ml” volumetric flask has a calibrated/graduated mark at exact volume of
“250mililitres” /“250centimetres”
“1l” volumetric flask has a calibrated/graduated mark at exact volume of “one
litre” /“1000 cubic centimeters”
“2l” volumetric flask has a calibrated/graduated mark at exact volume of “two
litres” /“2000 cubic centimeters”
5
...


A dropper/teat pipette is used to measure very small amount/ drops of liquid solution
by pressing the flexible rubber head
...
Beam balance
A beam balance has a pan where a substance of unknown mass is placed
...

The mass from a beam balance is in grams
...
Electronic/electric balance
...

The mass of the unknown substance in grams is available immediately on the screen
...

If temperature rises in the bulb, the alcohol /mercury expand along the thin narrow
enclosed outlet
...

A thermometer therefore determines the temperature when the bulb is fully dipped in
to the substance being tested
...

(d)Apparatus for measuring time
The stop watch/clock is the standard apparatus for measuring time
...

Common school stop watch/clock has start, stop and reset button for determining time
for a chemical reaction
...

(e) Apparatus for scooping
1
...
Both
ends of the spatula can be used at a time
...

2
...
Unlike a spatula, a deflagrating spoon is longer
...

1
...

A test tube is a narrow/thin glass apparatus open on one side
...

8

2
...

A boiling/ignition tube is a wide glass apparatus than a test tube open on one side
...

3
...

Beaker is a wide calibrated/graduated lipped glass/plastic apparatus used for
transferring liquid solution which do not normally require very accurate measurements
Beakers are named according to the maximum calibrated/graduated volume they can
hold e
...

“250ml” beaker has a maximum calibrated/graduated volume of “250mililitres” /“250
cubic centimeters”
“1l” beaker has a maximum calibrated/graduated volume of “one litre” /“1000 cubic
centimeters”
“5 l” beaker has a maximum calibrated/graduated volume of “two litres” /“2000 cubic
centimeters”
4
...

A conical flask is a moderately narrow glass apparatus with a wide base and no
calibration/graduation
...
It can also be put some solids
...

Conical flasks are named according to the maximum volume they can hold e
...

“250ml” Conical flasks hold a maximum volume of “250mililitres” /“250 cubic
centimeters”
“500ml” Conical flasks hold a maximum volume of “500ml” /“1000 cubic
centimeters”
5
...
Round bottomed flask thus carry/hold exact volumes of
liquids that have been measured using other apparatus
...
The flask can also hold (weighed) solids
...

6
...
It has no calibration/graduation
...
The narrow/thin mouth prevents spirage
...
A flat bottomed flask must be held/ clamped when in use because it’s
flat narrow base is not stable
...


1
...
Beakers
...

2
...
It is placed on top of
a tripod stand:
(i) Ensure even distribution of heat to prevent cracking glass apparatus
(ii) Hold smaller apparatus that cannot reach the edges of tripod
stand 3 Clamp stand
A clamp stand is a metallic apparatus which tightly hold apparatus at their “neck”
firmly
...
The height and
position of clamping is variable
...
Test tube holder
A test tube holder is a hand held metallic apparatus which tightly hold
test/boiling/ignition tube at their “neck” firmly on the other end
...

5
...

A pair of tong is a scissor-like hand held metallic apparatus which tightly hold firmly a
small solid sample on the other end
...
Gas jar
A gas jar is a long wide glass apparatus with a wide base
...
It is used to collect/put gases
...

(h) Apparatus for holding/directing liquid solutions/funnels (to avoid spillage)
...
Filter funnel
A filter funnel is a wide mouthed (mainly plastic) apparatus that narrow drastically at
the bottom to a long extension
...

Filter funnel is also used to place a filter paper during filtration
...
Thistle funnel

A thistle funnel is a wide mouthed glass apparatus that narrow drastically at the bottom
to a very long extension
...

A liquid solution can thus be directed into a stoppered container without spillage
3
...

The long extension is usually drilled through a stopper/cork
...

4
...

A liquid solution can thus be directed into a separating funnel without spillage
...

It is used to separate two or more liquid solution mixtures that form layers/immiscible
...

(h) Apparatus for heating/Burners
1
...

Any flammable fuel when put in a container and ignited can produce some heat
...
Bunsen burner
The Bunsen burner is the standard apparatus for heating in a Chemistry
school laboratory
...

(a)Diagram of a Bunsen burner

A Bunsen burner uses butane/laboratory gas as the fuel
...
It is tapped and distributed into the laboratory through gas pipes
...
If opened the gas tap
releases butane/laboratory gas
...

The Bunsen burner is fixed to the gas tap using a strong rubber tube
...
It controls the amount of air entering used during burning
...
If the collar side hole is not in line with chimney side hole, the air hole is said to
be “closed” If the collar side hole is in line with chimney side hole, the air hole is said
to be “open”
(v)Chimney- tall round metallic rod attached to the base plate
...
Adjust the collar to ensure the air holes are closed
...
Connect the burner to the gas tap using a rubber tubing
...

3
...

4
...

5
...


(c)Bunsen burner flames
A Bunsen burner produces two types of flames depending on the amount of air
entering through the air holes
...
If the air holes are
fully closed, a luminous flame is produced
...

Characteristic differences between luminous and non-luminous flame
Luminous flame
Non-luminous flame
1
...
Produced when the air holes are
fully/completely closed
...

2
...
when the air holes are fully/
completely
closed
there
is completely open there is complete
incomplete burning/ combustion of burning/ combustion of the laboratory
the laboratory gas
gas
3
...
Complete burning/ combustion of
the laboratory gas produces fine
the laboratory gas does not produce
unburnt carbon particles which make carbon particles
...

4
...
Is mainly blue in colour and is
white hot and emit light
...
This
is thus bright yellow in colour
makes non-luminous flame useful for
producing
light
...
Is larger, quiet
and wavy/easily 5
...
It is the
hottest region
(iii)
green region surrounded by the
blue region where there is complete
burning
(Ii) The region of unburnt gas at the
innermost surrounded by green and
blue regions
...
Three dimensions (3D) are
not recommended
...

(iii) Curved edges of the apparatus on a scientific diagram should be drawn using
free hand
...


CLASSIFICATION OF SUBSTANCES
Substances are either pure or impure
...

An impure substance is one which contains two or more substances
...

A mixture is a combination of two or more pure substances which can be separated by
physical means
...

Common mixtures include:
(a)Solutions/solid-liquid dissolved mixture
Experiment:
To make a solution of copper (II) sulphate (VI)/Potassium magnate(VII) /sodium
chloride
Procedure
Put about 100 cm3 of water in three separate beakers
...
Stir for about two minutes
...

A substance/liquid in which another substance dissolves is called solvent
...

When a solute dissolves in a solvent it forms a uniform mixture called solution
...
Water is referred as the universal solvent because it dissolves many
solutes
...
Soluble particles
uniformly spread between the particles of water/solvent and cannot be seen
...
g
...
Sodium chloride solution is a solution formed after dissolving sodium chloride
crystals/solid in water
...

Sodium chloride + Water -> Sodium chloride solution
NaCl(s)
+
(aq) -> NaCl(aq)
2
...

Ammonia exists in aqueous state after dissolving
...
Copper (II) sulphate (VI) solution is a solution formed after dissolving Copper (II)
sulphate (VI) crystals/solid in water
...

Copper (II) sulphate (VI) + Water -> Copper (II) sulphate (VI) solution
CuSO4(s)
+
(aq) -> CuSO4 (aq)
4
...

Potassium manganate(VII)exist in aqueous state after dissolving
...
Separately place a half spatula
end full of soil, maize and lead (II) Iodide to each beaker
...

Observation
Some soil, maize and lead (II) Iodide float in the water
A brown suspension/precipitate/particles suspended in water containing soil
A white suspension/precipitate/particles suspended in water containing flour
A yellow suspension/precipitate/particles suspended in water containing Lead (II)
iodide
...

Explanation
Some solid substances do not dissolve in a liquid
...
When an insoluble solid is put in liquid:
(i) Some particles remain suspended/floating in the liquid to form a suspension
/precipitate
...

An insoluble solid acquire the colour of the suspension/precipitate
...
g
...
A white suspension /precipitate have some fine white particles suspended
/floating in the liquid
...
A blue suspension /precipitate has some fine blue particles suspended /floating in
the liquid
...
A green suspension /precipitate has some fine green particles suspended /floating in
the liquid
...
A brown suspension /precipitate has some fine brown particles suspended /floating
in the liquid
...
A yellow suspension /precipitate has some fine yellow particles suspended /floating
in the liquid
...
Measure 50cm3 of water
...
Swirl for about one minute
...
Measure 50cm3 of turpentine oil
...
Swirl for about one
minute
...

Ethanol and water form a uniform mixture
...
Kerosene is miscible in turpentine oil
...
They do not form layers
...
The smaller particles occupy the spaces between the
bigger particles
...
Measure 50cm3 of turpentine oil
...
Swirl for about one minute
...
Measure 50cm3 of kerosene
...
Swirl for about one minute
...

Turpentine and water do not form a uniform mixture
...
Water is immiscible in turpentine oil
...
They form layers
...
The particles of one liquid
cannot occupy the spaces between the particles of the other
...
The less dense particles settle on top
...
On solidifying, a uniform mixture of the metals is
formed
...
In the alloy,
one metallic particle occupies the spaces between the metallic particles of the other
...

Alloy name
Constituents of the
Uses of the alloy

Brass

alloy
Copper and Zinc

Bronze

Copper and Tin

Making clock springs,
contacts and copper coins

Soldier

Lead and Tin

Soldering, joining electrical contacts
because of its low melting points and
high thermal conductivity

Duralumin

Aluminum,
Magnesium

Copper and Making aircraft, utensils, and windows
frames because of its light weight and
corrosion resistant
...


Nichrome

Making screws and bulb caps
electrical

and Provide resistance in electric heaters
and ovens

German silver Copper, Zinc and Nickel Making coins

METHODS OF SEPARATING MIXTURES
Mixtures can be separated from applying the following methods:
(a) Decantation
Sediments can be separated from a liquid by pouring out the liquid
...

Experiment
Put some sand in a beaker
...
Allow sand to settle
...

Observation
Sand settles at the bottom as sediments
...

Explanation
Sand does not dissolve in water
...
When poured out, the less dense water flows out
...
Filtration is thus
improved decantation
...

Experiment: To separate soil and water using filtration

Fold a filter paper to fit well into a filter funnel
...

Put one spatula end full of soil into 50cm3 of water
...
Put the soil/water mixture
into the filter funnel
...

Soil remains above the filter paper
...
The holes
allow smaller water particles to pass through but do not allow bigger soil particles
...
The solid which do not pass through is
called residue
...


(c)Evaporation
Evaporation is a method of separating a solute/solid from its solution
...
If a mixture contain insoluble solid, they are filtered
out
...

Procedure:
Put one spatula end full of soil on a filter paper
...
Mix
well using the spatula,
...

Put the contents of the filter paper into the water
...

Fold a filter paper into a filter funnel
...

Put the filtrate into an evaporating dish
...

Observation
(i)On mixing
Colourless crystals and brown soil particles appear on the filter paper
...
Soil particles do not dissolve in water
...


Brown residue collected above the filter funnel/paper
...

On adding water, common salt dissolves to form a solution
...

On filtration, a residue of insoluble soil does not pass through the filter paper
...

Common salt solution is collected as filtrate
...

Vapourization/evaporation can take place even without heating
...


Set up of apparatus

(d) Distillation
Distillation is an improved evaporation where both the solute and the solvent in the
solution are separated /collected
...
It involves heating the solution to
evaporate/vaporize the solvent out
...

Experiment: To obtain copper (II) sulphate (VI) crystals and water from copper
(II) sulphate (VI) solution
...

Place about 200cm3 of water into the beaker
...

Pour half portion of the contents in the beaker into a round bottomed/flat/conical flask
broken porcelain/sand/glass into the flask
...

Connect the flask to a Liebig condenser using delivery tube
...

Circulate water in the Liebig condenser
...

Observation
Copper (II) sulphate (VI) crystals dissolve in water to form a blue solution
...

Blue crystals are left in the flask
...

The liquid vapour/gas passes through the delivery tube to the Liebig condenser
...

This ensures efficient cooling
...

The water in the receiver would be warm
...

The condensed liquid collects in the receiver as distillate
...

During simple distillation, therefore, the solution is heated to vaporize /evaporate
the solvent/one component which is condensed at a different part of the apparatus
...

(ii) Ensure smooth and even boiling
...

o
Any mixture with a large difference /40 C in boiling point can be separated
using simple distillation
...

Fractional distillation involves:
(i) Heating the mixture in a conical/round bottomed /flat bottomed flask
...
e
...
Pure ethanol has a boiling point of 78 C
...

When a miscible mixture of ethanol and water is heated, ethanol vaporizes /boils/
evaporates first because it is more volatile
...

The purpose of the fractionating column is to offer areas of condensation for the less
volatile pure mixture
...

(iii)When the vapors rise they condense on the glass beads/broken glass /porcelain /
shelves which become hot
...

The less volatile pure substance trickles/drips back down the fractionating column or
back into the conical/round bottomed /flat bottomed flask to be heated again
...
g
...

Water condenses and then drip/trickle to the glass beads/broken glass /porcelain
/shelves lower in the fractionating column because it is less volatile
...
The Liebig
condenser has a cold water inlet and outlet circulation
...
It is collected as the first fraction
...

Pure substances have constant/fixed boiling point
...

o
E
...
the thermometer reading remains at78 C when ethanol is being separated
...

(vi)The second /subsequent fractions are collected in the receiver after noting a rise the
mercury/alcohol level in the thermometer
...
g
...
It is passed
through the Liebig condenser with the cold water inlet and outlet circulation
...

(vii)Each fraction collected should be confirmed from known physical/chemical
properties/characteristic
...
When it is put in a watch
glass then ignited, it catches fire and burn with a blue flame
...
When it is put in a watch glass
then ignited, it does not catch fire
...

Crude oil is a mixture of many fractions
...
In Kenya,fractional distillation
takes place at Changamwe in Mombasa
...


Air contain a mixture of three main useful gases which are condensed by cooling to very low
o
temperature (-200 C) to form a liquid
...
Nitrogen is the most volatile
o
o
(-196 C) and thus comes out as the first fraction
...
Oxygen ( at -183
very useful industrial gases
...
The three gases are

(f)Separation of immiscibles (Using a separating funnel)
Two or more liquids that form layers on mixing are immiscible
...
e
...
The less dense liquid floats on the denser one
...

Experiment: To separate an immiscible mixture of paraffin and water
...
Add about 100cm3 of paraffin into
the beaker
...

Transfer the mixture into a separating funnel
...

Open the tap, run out the lower layer out slowly into a clean beaker
...

Run out the intermediate small amount of the mixture near the tap into a beaker
...

Run out the remaining upper layer into a fresh beaker
...
Ignite
...

Two layers are formed on mixing
...
It does not catch fire
...
It catches fire and
burn with a yellow smoky flame
...
Water is denser than paraffin
...
On opening the tap, water runs out
...
It is not pure
...
The process
by which a solid changes to a gas is called sublimation
...
The process by which a gas changes to a solid is called
deposition
...

GAS

Sublimation

Deposition
SOLID

Some common substances that undergo sublimation/ deposition include:
(i)Iodine
(ii)Carbon(IV)oxide
(iii)Camphor
(iv)
ammonium chloride
(v)Iron(III)chloride
(vi)Aluminum(III)chloride
(vii) benzoic acid
If a mixture has any of the above as a component, then on heating it will change to a
gas and be deposited away from the source of heating
...
Add equal amount of sodium chloride crystals into the beaker
...

Place the beaker on a tripod stand
...
Place carefully the beaker containing
water on top of the beaker containing the solid mixture
...

Set up of apparatus:

Observation
(i)With ammonium chloride/common salt mixture
White fumes produced
...

Dark grey sublimate deposited
Colourless residue left
Explanation
(i)On heating a mixture of ammonium chloride and common salt, a white fume of
ammonium chloride is produced
...
Common salt remains as residue
...
The purple fumes solidify as dark grey sublimate on the cooler parts
...

Chemical equation:
Iodine solid
Iodine gas
I2(s)
I2 (g)
(h)Chromatography
Chromatography is a method of separating components of a solution mixture by
passing it through a medium where the different components move at different rates
...

Paper chromatography is a method of separating colored dyes by using paper as the
absorbent material
...

Practically, a simple paper chromatography involve placing a dye/material on the
absorbent material, adding slowly a suitable soluble solvent on the dye/material using a
dropper, the solvent spread out on the absorbent material carrying the soluble dye away
from the origin
...
The farthest
point the solvent spread is called solvent front
...

(ii) Stickiness of the dye-some dyes sticks on the absorbent material more than
other thus do not spread far from baseline
...
Put a drop of black/blue ink in the centre of the
filter paper
...
Using a clean teat
pipette/dropper add one drop of ethanol/propanone
...
Add about twenty other drops of ethanol waiting for about
one minute before each addition
...

Experiment: To investigate the colors in ink
Procedure
Method 2
Cut an 8 centimeter thin strip of a filter paper
...
Place the filter paper in a 10cm length boiling tube containing 5cm3 of ethanol
...

Cover the boiling tube
...
Remove the boiling tube and
allow the filter paper to dry
...
On adding an eluting
solvent, it dissolves the dye spread out with it
...
The least dense/sticky pure dye move farthest
...

Comparing the distance moved by a pure dye with a mixture, the coloured dyes in a
mixture can be deduced as below:
Example 1
The chromatogram of pure dyes A, B ,C and a dye mixture D is shown below
Determine the pure dyes present in D
...
Most nuts contain oil
...
A suitable
volatile solvent is added
...
The filtrate solvent is then allowed to
crystallize leaving the oil/fat
...
This is the test for the presence of oil/fat
...
Place the inner soft seed into a
mortar
...

Add a little propanone and continue crushing
...
Decant/filter
...
Vapourize the solvent using solar energy /sunlight
...

Observation /Explanation
Propanone dissolve fat/oil in the macadamia nuts
...
In sunlight/solar energy, propanone evaporate/vaporize
leaving oil/fat(has a higher boiling point)
...
When oil/fat is rubbed/ smeared on an opaque
paper, it becomes translucent
...

A crystal is the smallest regular shaped particle of a solute
...


Some solutions form crystals when heated
...
Some other solutions form crystals when cooled
...

Experiment; To crystallize copper (II) sulphate (VI) solution
Procedure:
Place about one spatula full of hydrated copper sulphate (VI) crystals into 200cm3 of
distilled water in a beaker
...
Continue adding a little more of the hydrated copper
sulphate (VI) crystals and stirring until no more dissolve
...
Cover the
filtrate with a filter paper
...

Preserve the experiment for about seven days
...
After some days water slowly evaporate leaving large
crystals of copper (II) sulphate
...

Physical/Temporary and Chemical changes
A physical/temporary change is one which no new substance is formed and is
reversible back to original
...

The following experiments illustrates physical and
chemical changes (a)Heating ice
Place about 10g of pure ice in a beaker
...
Record it at time
“0
...
Heat the ice on a strong Bunsen flame and determine its
temperature after every 60seconds/1minute to complete the table below:
Time/minutes 0
1
2
3
4
5
6
7
8
Temperature -2
0
0
40
80
90
95
95
96
o
( C)
Plot a graph of time against Temperature (y-axes)
Explain the shape of your graph
Melting/freezing/fusion/solidification and boiling /vaporization /evaporation are the
two physical processes
...

The boiling point of pure substance depends on external atmospheric pressure
...
Freezing is the physical
change of a liquid to solid
...
e
...


Condensation/ liquidification is the physical change of gas to liquid
...
e
...

Solids are made up of very strong bonds holding the particles very close to each other
(Kinetic Theory of matter)
...

(ii)Freezing/fusion/solidification involves cooling a liquid to reform /rejoin the very
strong bonds to hold the particles very close to each other as solid and thus lose their
degree of freedom (Kinetic Theory of matter)
...

(iii)Boiling/vaporization/evaporation involves heating a liquid to completely
break/free the bonds holding the liquid particles together
...

Boiling /vaporization / evaporation is an endothermic (+∆H) process that
require/absorb energy from the surrounding
...

It involves gaseous particles losing energy to the surrounding to form a liquid
...
THE ATMOSPHERE
1
...
Air is a mixture of colourless, odorless gases
which is felt as wind (air in motion)
...
Plants
use air for respiration and photosynthesis
...
The main gases present in the atmosphere/air:
Gas
Nitrogen
Oxygen
Carbon(IV)oxide
Noble gases
Water vapour

Approximate % composition by volume
78
...
0
0
...
0
Vary from region

3
...
Place a candle stick on a Petri dish
...
Cover it with the gas jar
...
Remove the gas jar
...
Carefully cover it with the gas
jar
...
Mark the new level of the water M3
...
In a closed system (vessel), the candle continues to burn using the
part of air that support burning/combustion
...
The
candle goes off/extinguished when all the active part of air is used up
...

The experiment is better when very dilute sodium/potassium hydroxide is used
instead of water
...
From the experiment above
the % composition of the:
(i) Active part of air can be calculated:
M2 - M3 x 100% => 10- 8 x 100% = 20%
M2
10cm
(ii) Inactive part of air can be calculated:
100% -20% = 80% // M3 => 8 x 100% = 80%
M2
10cm
(b)To find the composition of active part of air using heated
copper turnings
...
Seal the
ends with glass/cotton wool
...
Pull in
air into syringe “B”
...

Determine and record the volume of air in syringe “B” V1
...

Push all the air slowly from syringe “B” to syringe “A” as heating continues
...

After about ten minutes, determine the new volume of air in syringe “B” V 2
Set up of apparatus

Sample observations
Colour change from brown to black
Volume of air in syringe “B” before heating V1
= 158
...
2cm3
Volume of air in syringe “B” used by copper V1 - V2 = 30
...
What is the purpose of:
(i) glass/cotton wool
To prevent/stop copper turnings from being blown into the syringe/out of the glass tube
(ii) Passing air through the glass tube repeatedly
To ensure all the active part of air is used up
(iii) Passing air through the glass tube slowly
To allow enough time of contact between the active part of and the heated copper
turnings

2
...
Colour change from brown to black

Brown copper metal reacts with the active part of air/oxygen to form black copper (II)
oxide
...
Copper only react with oxygen when heated
...
Calculate the % of
(i) Active part of air
% active part of air = V1 - V2 x 100%
=> 30
...
493%
V1
158
...
2cm3 x 100% = 80
...
0cm3
Method 2
% inactive part of air = 100% -% active part of air
=> 100 % - 19
...
507%
4
...
Explain
...
State the main gases that constitute:
(a )active part of air
...
If the copper turnings are replaced with magnesium shavings the % of active
part of air obtained is extraordinary very high
...

Magnesium is more reactive than copper
...
It
generates enough heat for magnesium to react with both oxygen and nitrogen in the air
...
This
considerably reduces the volume of air left after the experiment
...
Record the
volume of the graduated cylinder V1
...
Immediately place a cover slip firmly on the mouth of the gas jar
...

Invert the gas jar in a trough/basin containing water
...

Level of water in gas jar rises when inverted in basin/trough
...
Which gas is absorbed by alkaline pyrogallol/1,2,3-trihydroxobenzene
Oxygen
2
...
What is the purpose of paper cover?
To ensure no air enters into the lime water
...
What happens when water enters the flask?
It forces the air from the flask into the lime water
...
What is observed when the air is bubbled in the lime water?
A white precipitate is formed
...

4
...
State the chemical test for the presence of carbon (IV) oxide gas based on 4(a)
and (b) above:
Carbon (IV) oxide forms a white precipitate with lime water that dissolves in excess
of the gas
...
State the composition of carbon (IV) oxide gas by volume in the air
...
03% by volume
B
...

1
...
g
...
About 70% of the earth is water made up of Hydrogen and Oxygen
...
About 20% by volume of the atmospheric gases is Oxygen that form the active
part of air
...

Oxygen was first prepared in 1772 by Karl Scheele and later in 1774 by Joseph
Priestly
...
Place a bee hive shelf/stand into the water
...

Clamp a round bottomed flask and set up the apparatus as below
...

Sample observation questions
1
...
Describe the colour and smell of the gas
Colourless and odorless
3
...

-Over water
-Upward delivery
-Down ward displacement of water
(b)What property of Oxygen makes it to be collected using the method
above? -Slightly soluble in water
4
...

A catalyst is a substance that speeds up the rate of a chemical reaction but remain
chemically unchanged at the end of the reaction
...

A little Manganese (IV) oxide speeds up the rate of decomposition by reducing the
time taken for a given volume of Oxygen to be produced
...
Write the equation for the reaction
...
Lower a glowing splint slowly into a gas jar containing Oxygen gas
...

The glowing splint relights/rekindles
Oxygen relights/rekindles a glowing splint
...
Add four drops of
phenolphthalein indicator
...


Completely fill a gas jar with water and invert in onto the bee hive shelf/stand
...


Collect several gas jars of Oxygen covering each sample
...
What is observed when water is added?
(i) Into the flask containing sodium peroxide
Rapid effervescence/bubbling/fizzing
(ii) Phenolphththalein
Remains colourless /Phenolphthalein indicator is colourless in neutral solution
2
...
(a)Name the method of gas collection used
...
Oxygen is slightly soluble in water
...
Test the gas by lowering a glowing splint slowly into a gas jar containing
the prepared sample
...
This confirms the presence of Oxygen gas
5
...

Sodium peroxide + Water -> Sodium hydroxide +
Oxygen
2Na2O2 (aq)
+ 2H2O (l) -> 4NaOH (aq)
+
O2 (g)

1
...

The glowing splint relights/rekindles
...
Write the equation for the reaction
...
What is the purpose of manganese (IV)
oxide? Manganese (IV) oxide is catalyst
...

Potassium Chlorate (V) decomposes slowly to form potassium chloride and Oxygen
gas
...

(c)Uses of Oxygen
1
...

This is mainly in:
(i)Mountain climbing/Mountaineering-at high altitudes, the concentration of
air/oxygen is low
...

(ii) Deep sea diving-Deep sea divers carry their own supply of Oxygen
...

2
...

(i) Oxy-acetylene/ethyne flame is produced when Ethyne/acetylene gas is burnt
o
in pure oxygen
...
It is used for
welding /cutting metals
...

o
The flame has a temperature of about 2000 C
...

3
...
A mixture of charcoal, petrol and liquid Oxygen is an explosive
...

Oxygen is a very reactive non metal
...

Burning/combustion is the reaction of Oxygen with an element/substances
...

Burning/combustion are an example of an oxidation reaction
...
They turn blue litmus red
...
g
...
They don’t turn blue or red litmus
...
g
...
They turn red litmus blue
...
g
...

(i)Reaction of metals with Oxygen/air
The following experiments show the reaction of metals with Oxygen and air
...
Burning Magnesium
Procedure
(a)Cut a 2cm length piece of magnesium ribbon
...
Remove it when it catches fire
...

Place the products in a beaker containing about 5cm3 of water
...
Using a pair of tongs introduce
it to a Bunsen flame
...

Place about 5cm3 of water into the gas jar
...
Test the solution/mixture using litmus papers
Observations
(a)In air
Magnesium burns with a bright blindening flame in air forming white solid/ash
/powder
...
Blue litmus paper
remains blue
...
No effervescence/bubbles/ fizzing
...

Blue litmus paper remains blue
...
Both Magnesium Oxide
and Magnesium nitride are white solid/ash /powder
...
Ammonia is also an alkaline/basic gas that
has a pungent smell of urine
...
Burning Sodium
Procedure
(a)Carefully cut a very small piece of sodium
...
Remove it when it catches fire
...

Place the products in a beaker containing about 20cm3 of water
...
Using a deflagrating spoon
introduce it to a Bunsen flame
...

Place about 20 cm3 of water into the gas jar
...
Test the solution/mixture using litmus papers
Observations
(a)In air

Sodium burns with a yellow flame in air forming a black solid
...
Red litmus paper turns blue
(b) In pure Oxygen

Sodium burns faster with a golden yellow flame in pure oxygen forming a yellow
solid
...
Gas produced relights glowing splint
...
Red litmus paper turns blue
...
Oxygen is produced
...
Burning Calcium
Procedure
(a)Using a pair of tongs hold the piece of calcium on a bunsen flame
...

Place the products in a beaker containing about 2cm3 of water
...
Quickly
lower it into a gas jar containing Oxygen gas
...
Place about 2cm3 of water
...

Test the solution/mixture using litmus papers
Observations
(a)In air
Calcium burns with difficulty producing a faint red flame in air forming a white solid
...
Red litmus paper turns blue
(b) In pure Oxygen
Calcium burns with difficulty producing a less faint red flame Oxygen forming a white
solid
...
Red litmus paper turns blue
Explanation

(a)Calcium burns in air forming white calcium Oxide
...

Chemical equations
Calcium +
Oxygen/air
->
calcium Oxide
2Ca(s) +
O2(g)
->
2CaO(s)
Small amount of Calcium Oxide dissolves in water to form a basic/alkaline solution
of Calcium hydroxide
...

Chemical equations
Calcium Oxide +
Water
->
Calcium hydroxide
CaO(s)
+
H2O (l)
->
Ca (OH) 2 (aq)
IV
...

Observe
...
Test
the solution/mixture using litmus papers
(b)Using a pair of tongs hold another piece of Iron wool/steel wire on a Bunsen flame
...
Observe
...
Swirl
...

Blue litmus paper remains blue
...
Blue litmus paper remains blue
...

Chemical equations
Calcium Oxide +
Water
->
Iron (III) hydroxide
Fe2O3(s)
+
3H2O (l)
->
2Fe (OH) 3 (s)
V
...

Observe
...
Test the
solution/mixture using litmus papers
(b)Using a pair of tongs hold another piece of Copper turnings/shavings on a Bunsen
flame
...
Observe
...
Swirl
...
Blue litmus paper remains blue
...
Blue litmus paper remains blue
...

Chemical equations
Copper (II) Oxide +
Water ->
Copper (II) hydroxide
CuO(s)
+
H2O (l)
->
Cu (OH) 2 (s)
(i)Reaction of non metals with Oxygen/air
The following experiments show the reaction of non metals with Oxygen and air
...
Burning Carbon
Procedure
(a)Using a pair of tongs hold a dry piece of charcoal on a Bunsen flame
...

Place the products in a beaker containing about 2cm3 of water
...

Quickly lower it into a gas jar containing Oxygen gas
...

Place about 2cm3 of water
...
Test the solution/mixture using litmus
papers Observations
-Carbon chars then burns with a blue flame
-Colourless and odorless gas produced
-Solution formed turn blue litmus paper faint red
...

Explanation

Carbon burns in air and faster in Oxygen with a blue non-sooty/non-smoky flame
forming Carbon (IV) oxide gas
...

Carbon (IV) oxide gas dissolves in water to form weak acidic solution of Carbonic (IV)
acid
...
Burning
Sulphur Procedure
(a)Using a deflagrating spoon place sulphur powder on a Bunsen flame
...

Place the products in a beaker containing about 3cm3 of water
...
Slowly
lower it into a gas jar containing Oxygen gas
...

Place about 5cm3 of water
...
Test the solution/mixture using litmus papers
...
Red litmus paper remains red
...

Sulphur (IV) oxide gas dissolves in water to form weak acidic solution of Sulphuric
(IV) acid
...
Burning
Phosphorus Procedure

(a)Remove a small piece of phosphorus from water and using a deflagrating spoon
(with a lid cover) places it on a Bunsen flame
...

Carefully put the burning phosphorus to cover gas jar containing about 3cm3 of water
...

Slowly lower it into a gas jar containing Oxygen gas with about 5 cm3 of
water
...

Swirl
...

Observations
-Phosphorus catches fire before heating on Bunsen flame
-Dense white fumes of a gas produced that has pungent choking poisonous
smell -Solution formed turn blue litmus paper faint red
...

Explanation
Phosphorus is stored in water
...

Phosphoric (V) oxide gas dissolves in water to form weak acidic solution of
Phosphoric (V) acid
...

The reactivity series is a list of elements/metals according to their affinity for oxygen
...

A metal/element with higher affinity for oxygen is placed higher/on top of the one
less affinity
...
A metal/element with higher affinity for
oxygen removes Oxygen from a metal lower in the reactivity series/less affinity for
Oxygen
...

When metal/element donate/lose Oxygen, the process is called Reduction
...

An element/metal/compound that undergoes Reduction is called Oxidizing agent
...

Redox reaction between Magnesium and copper (II)
Oxide Procedure
Place about 2g of copper (II) oxide in a crucible with a lid
...
Mix thoroughly
...

Heat strongly for five minutes
...
Open the lid
...

Observation
Colour change from black to brown
...

Explanation
Magnesium is higher in the reactivity series than Copper
...

When a mixture of copper (II) oxide and Magnesium is heated, Magnesium reduces
copper (II) oxide to brown copper metal and itself oxidized to Magnesium oxide
...

Copper (II) oxide is the oxidizing agent because it undergoes redox reduction process
...

The reaction of Magnesium and Copper (II) oxide is a
reaction Chemical equation
Reduction process
Oxidation process

1
...
Zinc (II) oxide + Magnesium -> Magnesium oxide + Zinc
(yellow when hot)
(white ash/solid)
(grey)
ZnO(s)
+
Mg(s)
->
MgO(s)
+
Zn(s)
(Oxidizing agent) (Reducing agent)
3
...
An ore is a rock
containing mineral element which can be extracted for commercial purposes
...

Metallic ores that naturally occur as metallic sulphides are first roasted in air to form
the corresponding oxide
...
e
...

Copper (I) sulphide + Oxygen
-> Copper (I) Oxide + Sulphur (IV) oxide
Cu2S(s)
+ O2 (g)
-> 2Cu(s)
+ SO2 (g)
Zinc (II) sulphide
+ Oxygen
-> Zinc (II) Oxide + Sulphur (IV) oxide
ZnS(s)
+ O2 (g)
-> Zn(s)
+ SO2 (g)
Lead (II) sulphide
+ Oxygen
-> Lead (II) Oxide + Sulphur (IV) oxide
PbS(s)
+ O2 (g)
-> Pb(s)
+ SO2 (g)
Iron (II) sulphide
+ Oxygen -> Iron (II) Oxide + Sulphur (IV) oxide
FeS(s)
+ O2 (g)
-> Fe(s)
+ SO2 (g)
Metallic ores that naturally occur as metallic carbonates are first heated in air
...


...
g
...
WATER
Pure water is a colourless, odorless, tasteless, neutral liquid
...
The main sources of water include
rain, springs, borehole, lakes, seas and oceans: Water is generally used for the
following purposes:
(i) Drinking by animals and plants
...

(iii) Bleaching and dyeing
...

(v) Cooling industrial processes
...

It is therefore called universal solvent
...

Water naturally exists in three phases/states solid ice, liquid water and gaseous water
vapour
...

The natural interconvertion of the three phases/states of water forms the water cycle
...


OCEAN,LAKES,SEAS(water as liquid)

Liquid water in land, lakes, seas and oceans use the solar/sun energy to
evaporate/vapourize to form water vapour/gas
...


During evaporation, the water vapour rises up the earth’s surface
...
Water vapour therefore cools as
o
it rises up
...

The process by which a gas/water vapour changes to a liquid is called
condensation/liquidification
...
The process by
which a liquid/water changes to a ice/solid is called freezing/solidification
...
When the clouds become too heavy they fall to the earth’s surface as
rain/snow as the temperature increase with the fall
...

Whether a substance is water can be determined by using the following methods:

a) To test for presence of water using anhydrous copper (II) suphate (VI)
Procedure
Put about 2g of anhydrous copper (II) sulphate (VI) crystals into a clean test tube
...
Repeat the procedure using distilled water
...
On adding water, anhydrous copper (II)
sulphate (VI) gains/reacts with water to form hydrated copper (II) sulphate (VI)
...
Hydrated copper (II) sulphate (VI) contains
water of crystallization
...
5H2O(s)
b) To test for presence of water using anhydrous cobalt (II)
chloride Procedure
Put about 5cm3 of water into a clean test tube
...

Repeat the procedure using distilled water
...
On adding water, anhydrous cobalt (II)
chloride gains/reacts with water to form hydrated cobalt (II) chloride
...

Hydrated cobalt (II) chloride contains water of crystallization
...

Anhydrous
Hydrated
cobalt (II) chloride + Water -> cobalt (II) chloride
(Blue)
(pink)
CoCl2 (s)
+ 5H2O (l) -> CoCl2
...
Carbon (IV) oxide gas is
also produced if the air is sufficient/excess
...


Put about 5cm3 of lime water in a boiling tube
...
Place it below an inverted thistle/filter funnel
Collect the products of the burning candle by setting the apparatus as below
Set up of apparatus

Observation
The sanction pump pulls the products of burning into the inverted funnel
...
A white precipitate is
formed in the lime water/calcium hydroxide
...

Water turns anhydrous copper (II) sulphate (VI) changes from white to blue
...

Since:
(i) hydrogen in the wax burn to form water
Hydrogen +Oxygen ->Water
(from candle)
(from the air)
2H2 (g) +
O2 (g)
->
2H2O (g/l)
(ii) carbon in the wax burn to form carbon (IV) oxide
Hydrogen +Oxygen ->Water
(from candle)
(from the air)
C(s)
+
O2(g)
->
CO2 (g)
The candle before burning therefore contained only Carbon and Hydrogen only
...
A candle is a
hydrocarbon
...

Hydrocarbons burn in air to form water and carbon (IV) oxide gas
...

Sources of water pollution include:
(i)Industrial chemicals being disposed into water bodies like rivers, lakes and oceans
...

(iii)Leaching of insecticides/herbicides form agricultural activities into water
bodies
...

(v)Petroleum oil spilling by ships and oil refineries
(vi)Toxic/poisonous gases from industries dissolving in rain
...
This reduces the quantity of
dissolved Oxygen in the water killing the aquatic fauna and flora
...

(ii) Use of biological control method instead of insecticides and herbicides
(iii) Using biodegradable detergents

REACTION OF WATER WITH METALS
...
The reaction of metals with water
depends on the reactivity series
...
The following experiments shows the reaction of metals
with cold water and water vapour/steam
...
Add three drops of phenolphthalein
indicator/litmus solution/universal indicator solution/methyl orange indicator into the
water
...
Using a pair of forceps put the metal into the
water
...

Effervescence/fizzing/ bubbles of colourless gas produced
...
Sodium floats on water and vigorously reacts to form
an alkaline solution of sodium hydroxide and producing hydrogen gas
...

Chemical equation
Sodium
+
Water
->
Sodium hydroxide + Hydrogen gas
2Na(s)
+
2H2O (l) ->
2NaOH (aq)
+ H2(g)
To collect hydrogen gas, Sodium metal is forced to sink to the bottom of the
trough/beaker by wrapping it in wire gauze/mesh
...
On contact with water it explodes/burst into
flames
...

(b)Reaction of Lithium/ Calcium with cold water:
Procedure
Put about 200cm3 of water in a beaker
...

Cut a small piece of Lithium
...

Repeat with a piece Calcium metal
Observation

Lithium sinks to the bottom of the water
...

Colour of phenolphthalein turns pink
Colour of litmus solution turns blue
Colour of methyl orange solution turns Orange
Colour of universal indicator solution turns blue
Explanation
Lithium and calcium are denser than water
...
Lithium is more reactive than calcium
...

Chemical equation
Lithium
+ Water
-> Lithium hydroxide + Hydrogen gas
2Li(s)
+ 2H2O (l)
-> 2LiOH (aq) + H2 (g)
Calcium
+ Water
-> Calcium hydroxide + Hydrogen gas
Ca(s)
+ 2H2O (l)
-> Ca (OH) 2(aq)
+ H2 (g)

(c) Reaction of Magnesium/Zinc/ Iron with Steam/water vapour:
Procedure method1
Place some wet sand or cotton/glass wool soaked in water at the bottom of an
ignition/hard glass boiling tube
...

Coil it at the centre of the ignition/hard glass boiling tube
...

Heat the wet sand or cotton/glass wool soaked in water gently to:
(i) Drive away air in the ignition/hard glass boiling tube
...
Repeat the experiment using
Zinc powder and fresh Iron filings
...

(iii)With Iron fillings:
The Iron fillings turn red hot on strong heating
Dark blue solid formed
Dark blue solid formed does not dissolve in water
...

Coil it at the centre of a hard glass tube
Set up the apparatus as below
...

(ii) generate steam
Heat the coiled ribbon strongly using another burner
...


Observations
(i)With Magnesium ribbon:
The Magnesium glows with a bright flame (and continues to burn even if heating
is stopped)
White solid /ash formed
White solid /ash formed dissolve in water to form a colourless solution Colourless
gas produced/collected that extinguish burning splint with “pop sound”
(ii) With Zinc powder:
The Zinc powder turns red hot on strong heating
Yellow solid formed that turn white on cooling
White solid formed on cooling does not dissolve in water
...

Explanations
(a)Hot magnesium burn vigorously in steam
...
White Magnesium
oxide solid/ash is left as residue
...
It extinguishes a burning splint with a “pop sound”
...

Hydrogen gas is produced
...

Chemical Equation
Zinc + Steam ->
Zinc oxide + Hydrogen
Zn(s) + H2O(g)
->
ZnO(s)
+
H2(g)
Zinc oxide does not dissolve in water
...

Hydrogen gas is produced
...

Chemical Equation
Iron
+ Steam ->
Tri iron tetra oxide + Hydrogen
2Fe(s)
+ 4H2O(g ->
Fe2O4(s)
+ 4H2(g)
Tri iron tetra oxide does not dissolve in water
...

(e) Lead, Copper, Mercury, Silver, Gold and Platinum do not react with either water or
steam
...
It occurs as Water and in Petroleum
...
Add dilute sulphuric (VI) /Hydrochloric
acid
...

Collect the gas produced over water as in the set up below
...
Collect several gas jars
...

When the acid comes into contact with the metal, there is rapid effervescence/ bubbles
/fizzing are produced and a colourless gas is produced that is collected:
(i) Over water because it is insoluble in water
(ii) Through downward displacement of air/upward delivery because it is
less dense than air
...
It contains air that was present in the apparatus
...

Chemical equation
(a) Zinc + Hydrochloric acid -> Zinc chloride
+ Hydrogen
Zn(s) + 2HCl (aq)
->
ZnCl2 (aq)
+
H2 (g)
Ionic equation
+

Zn (s) + 2H (aq) ->
Zinc + Sulphuric (VI) acid

2+

Zn (aq)
+
H2 (g)
-> Zinc Sulphate (VI) + Hydrogen

Zn(s)
+ H2SO4 (aq)
->
ZnSO4 (aq)
+ H2 (g)
Ionic equation
+
2+
Zn (s) + 2H (aq)
-> Zn (aq)
+
H2 (g)
(b) Chemical equation
Magnesium +
Hydrochloric acid -> Magnesium chloride +
Hydrogen
Mg(s)
+ 2HCl (aq)
->
MgCl2 (aq)
+
H2(g)
Ionic equation
+
2+
Mg (s) + 2H (aq)
-> Mg (aq)
+
H2 (g)
Magnesium + Sulphuric (VI) acid -> Magnesium Sulphate(VI) + Hydrogen
Mg(s) +
H2SO4 (aq)
->MgSO4 (aq)
+
H2(g)
Ionic equation
+
2+
Mg (s) + 2H (aq)
-> Mg (aq)
+
H2 (g)
(c) Chemical equation
Iron + Hydrochloric acid -> Iron (II) chloride +
Hydrogen
Fe(s)
+ 2HCl (aq)
->
FeCl2 (aq)
+ H2 (g)
Ionic equation
+
2+
Fe (s) + 2H (aq)
-> Fe (aq)
+
H2 (g)
Iron
+ Sulphuric (VI) acid -> Iron (II) Sulphate (VI) + Hydrogen
Fe(s)
+ H2SO4 (aq)
-> FeSO4 (aq)
+ H2 (g)
Ionic equation
+
2+
Fe (s) + 2H (aq)
-> Fe (aq)
+
H2 (g)
Note
1
...
Nitric (V) acid is a strong oxidizing agent
...

(ii) Dilute sulphuric (VI) acid with calcium/Barium/Lead because Calcium sulphate
(VI), Barium sulphate (VI) and Lead (II) sulphate (VI) salts formed are insoluble
...

(iii) Dilute acid with sodium/potassium
...

Properties of Hydrogen gas
(a)Physical properties
1
...
When mixed with air it has
a characteristic pungent choking smell
2
...

3
...
It can be transferred by inverting one gas jar over
another
...
Hydrogen does not support burning/combustion
...


II
...
When a stream of
pure dry hydrogen is ignited, it catches fire and continues to burn with a blue flame
...
Impure (air mixed with) hydrogen burns with an explosion
...

This is the confirmatory test for the presence of Hydrogen gas
...

(ii)Redox in terms of Hydrogen transfer
Redox can also be defined in terms of Hydrogen
transfer
...

Black copper (II) oxide is reduced to brown copper metal
...
Hydrogen
gas is oxidized to Water
...
Set
up of apparatus

(a)Chemical equation
(i) In glass tube
Copper (II) Oxide + Hydrogen
->
Copper +
(oxidizing agent) (reducing agent)
(black)
(brown)
CuO (s)
+
H2(g)
->
Cu(s)
+
(ii) when excess Hydrogen is burning
...

Oxygen
+
Hydrogen
->
Water
O2 (g)
+
2H2 (g)
->
2H2O(l)
(c)Chemical equation
(i) In glass tube
Iron (III) Oxide + Hydrogen
->
Iron + Hydrogen gas
(oxidizing agent) (reducing agent)
(Dark grey)
(grey)
Fe2O3 (s)
+
3H2 (g)
->
Fe(s)
+
3H2O (l)
(ii) when excess Hydrogen is burning
...
The substance formed when an
element burn in air is the oxide of the element
...
The oxide of Hydrogen is
called water
...

The gas is then ignited
...
A freezing mixture is a mixture of water and ice
...


Tests
(a) When about 1g of white anhydrous copper (II) sulphate (VI) is added to a sample
of the liquid, it turns to blue
...

(b) When blue anhydrous cobalt (II) chloride paper is dipped in a sample of the liquid,
it turns to pink
...

o
(c)When the liquid is heated to boil, its boiling point is 100 C at sea
level/one atmosphere pressure
...

Uses of Hydrogen gas
1
...

When Hydrogen is passed through unsaturated compounds in presence of Nickel
o
catalyst and about 150 C, they become saturated
...
They become saturated and hard through hydrogenation
...
In weather forecast balloons
...
Meteorological data is collected for analysis by
sending hydrogen filled weather balloons to the atmosphere
...

3
...

Ammonia gas is a very important raw material for manufacture of agricultural
fertilizers
...
In the manufacture of Hydrochloric acid
...
Hydrogen chloride gas is dissolved in water to form Hydrochloric acid
...

5
...

Fixed proportions of Hydrogen and Oxygen when ignited explode violently producing
a lot of energy/heat
...

6
...

A cylinder containing Hydrogen when ignited in pure Oxygen from a second cylinder
produces a flame that is very hot
...

Sample revision questions
1
...

(a)Why is it wrong to conclude the liquid was pure water?
Anhydrous copper (II) sulphate (VI) test for presence of water
...

(b)Write an equation for the reaction that takes place with anhydrous copper (II)
sulphate (VI)
Anhydrous copper (II) sulphate (VI) + Water -> hydrated copper (II) sulphate (VI)

CuSO4(s)
+ 5H2O (l) ->
CuSO4
...
6H2O
(ii)Write the equation for the reaction
Anhydrous cobalt (II) chloride + Water
-> hydrated cobalt (II) chloride
CoCl2 (s)
+ 6H2O(l) ->
CoCl2
...
Metal B reacts with steam
...
Metal A does not
react with water
...

B
C
A
(b)A product residue in D which was brown when hot but turned yellow on
cooling during the reaction of metal B was formed
...

Identify
(i)Metal B
Lead/Pb
(ii)Residue D Lead (II) oxide/PbO
(iii)Gas E
Hydrogen/H2
(c)A portion of product residue in D was added dilute nitric (V) acid
...
State and
explain the observations made
...

Lead (II) Oxide + dilute nitric (V) acid -> Lead (II) nitrate (V) + Water
PbO (s) + 2HNO3 (aq) -> Pb (NO3)2 (aq) + H2O (l)
When added dilute sulphuric (VI) acid, D does not dissolve
...
Lead(II)Oxide reacts with sulphuric(VI)acid to
form insoluble Lead(II)sulphate(VI) that cover/coat unreacted Lead(II)Oxide, stopping
further reaction
...
(a) Hydrogen can reduce copper (II) Oxide but not alluminium oxide
...

(i) What causes this ignition?
(ii) Write an equation to show how this ignition occurs
2
...

(b) Describe how copper could be obtained from the mixture containing copper
(II) oxide
3
...


(a) Identify solid X and state its purpose
Solid X
...

(b) Write a chemical equation for the reaction that produces the flame
...
Gas P was passed over heated magnesium ribbon and
hydrogen gas was collected as shown in the diagram below:

(i)
Name
gas

...
When hydrogen is burnt and the product cooled, the following results are obtained
as shown in the diagram below:
Clamp
Burning

Clamp
Ice cold water

Dry hydrogen
Liquid Y

(a) Write the equation for the formation of liquid Y
(b) Give a chemical test for liquid Y
Jane set-up the experiment as shown below to collect a gas
...


N

(a) Between N and M which part should be heated first? Explain
(b) Write a chemical equation for the reaction occurring in the combustion tube
...

The set-up below was used to investigate electrolysis of a certain molten
compound;-

(a) Complete the circuit by drawing the cell in the gap left in the diagram
(b) Write half-cell equation to show what happens at the cathode
(c) Using an arrow show the direction of electron flow in the diagram above
9
...

a) Write an equation for the reaction
...

c) Explain why copper metal cannot be used to prepare hydrogen gas
...

(i) Write an equation for the reaction
...

e) Give two uses of hydrogen gas
...
Write
an equation for the reaction
...
Element R does not react
with dilute acids
...
P reacts with cold
water
...

h) Explain how hydrogen is used in the manufacture of margarine
...
a) The set-up below is used to investigate the properties of hydrogen
...

Explain
iii) Write an equation for the reaction that occurs in the combustion tube
iv) When the reaction is complete, hydrogen gas is passed through the apparatus until
they cool down
...
The set up below was used to collect gas K, produced by the reaction
between water and
calcium metal
...

(b) At the end of the experiment, the solution in the beaker was found to be a
weak base
...
In a school laboratory:
(i)An acid may be defined as a substance that turns litmus red
...

Litmus is lichen found mainly in West Africa
...
It is thus able to identify/show
whether another substance is an acid, base or neutral
...

2
...
Citric acid

Occurrence
Found in ripe citrus fruits like passion
fruit/oranges/lemon
2
...
Lactic acid
Found in sour milk
4
...
Methanoic acid
Present in ants, bees stings
6
...
Butanoic acid
Present in cheese
8
...
Most commonly used acids found in a school laboratory are not naturally occurring
...
They are called mineral acids
...
Mineral acids are manufactured to very high concentration
...

In a school laboratory, they are mainly used when added a lot of water
...
Diluting ensures the concentration of the acid is safely low
...
Bases are opposite of acids
...

Bases which dissolve in water are called alkalis
...
Indicators are useful in identifying substances which look-alike
...

An acid-base indicator works by changing to different colors in neutral, acidic
and alkaline solutions/dissolved in water
...
Crush them using a pestle
...

Add about 5cm3 of propanone/ethanol and carefully continue grinding
...

Filter the extract into a clean 100cm3 beaker
...

(c)Put about three drops of the extract in (a)to each test tube in (b)
...

Sample observations
Solution mixture Colour on
adding indicator Nature of solution
extract
wood ash
green
Base/alkaline
soap solution
green
Basic/alkaline
ammonia solution green
Basic/alkaline
sodium hydroxide green
Basic/alkaline
hydrochloric acid Red
Acidic
distilled water
orange
Neutral
sulphuric(VI)acid Red
Acidic
sour milk
green
Basic/alkaline
sodium chloride
orange
Neutral
Toothpaste
green
Basic/alkaline

calcium hydroxide green
Basic/alkaline
Lemon juice
Red
Acidic
The plant extract is able to differentiate between solutions by their nature
...

(i)Since lemon juice is a known acid, then sulphuric (VI) and hydrochloric acids are
similar in nature with lemon juice because the indicator shows similar colors
...

(ii)Since sodium hydroxide is a known base/alkali, then the green colour of indicator
shows an alkaline/basic solution
...

7
...
A commercial indicator is
cheap, readily available and easy to store
...

Experiment:
Using commercial indicators to determine acidic, basic/alkaline and neutral
solutions
Procedure
Place 5cm3 of the solutions in the table below
...

Repeat with phenolphthalein indicator, methyl orange, screened methyl orange
and bromothymol blue
...

Indicator
Colour of indicator in
Acid
Base/alkali
Neutral
Litmus paper/solution Red
Blue
Colourless
Methyl orange
Red
Yellow
Red
Screened
methyl Purple
Orange
Orange
orange
Phenolphthalein
Colourless
Purple
Colourless
Bromothymol blue
Orange
Blue
Orange
The universal indicator
The universal indicator is a mixture of other indicator dyes
...
The pH scale shows the strength of bases and acids
...
These numbers are called pH values:
(i) pH values 1, 2, 3 shows a substance is strongly acid
(ii) pH values 4, 5, 6 shows a substance is a weakly acid
(iii) pH value 7 shows a substance is a neutral
(iv) pH values 8, 9, 10, 11 shows a substance is a weak base/alkali
...
The pH chart is a multicolored paper
with each colour corresponding to a pH value
...
e
(i) red correspond to pH 1, 2, 3 showing strongly acidic solutions
...

(iii)Green correspond to pH 7 showing neutral solutions
...

(v)Purple/dark blue correspond to pH 12,13,14 showing strong alkalis
...

When determining the pH of a unknown solution using
(i) pH paper then the pH paper is dipped into the unknown solution
...
The new colour is marched/compared to its corresponding one on the
pH chart to get the pH value
...
It changes/turn to a
certain colour
...

Experiment: To determine the pH value of some solutions
(a)Place 5cm3 of filtered wood ash, soap solution, ammonia solution, sodium
hydroxide, hydrochloric acid, distilled water, sulphuric (VI) acid, sour milk, sodium
chloride, toothpaste and calcium hydroxide into separate test tubes
...
Record the observations made in each case
...
Determine the pH value of each solution
...
All the mineral acids Hydrochloric, sulphuric (VI) and nitric (V) acids are
strong acids
2
...
Ammonia solution is a weak base/alkali
...

3
...

4
...

5
...

Properties of acids
(a)Physical properties of acids
1
...
Most acids are colourless liquids
3
...
Organic acids have characteristic smell
4
...
All acids turn blue litmus paper red, methyl orange red and
phenolphthalein colourless
...
All acids dissolve in water to form an acidic solution
...

(b)Chemical properties of acids
1
...

Metal
+
Acid -> Salt +
Hydrogen gas
Experiment: reaction of metals with mineral acids
...
Add 1cm length of
polished magnesium ribbon
...
Light a wooden
splint
...
Release the thump
stopper
...

(b)Repeat the procedure in (a) above using Zinc granules, iron filings, copper turnings,
aluminum foil in place of Magnesium ribbon
(c)Repeat the procedure in (a) then (b) using dilute sulphuric (VI) acid in place of
dilute hydrochloric acid
...

Explanation
Some metals react with dilute acids, while others do not
...
Hydrogen gas is a colourless gas that extinguishes a
burning splint with a pop sound
...

This hydrogen is displaced/removed from the acids by some metals like Magnesium,
Zinc, aluminium, iron and sodium
...

Chemical equations
1
...
Zinc + Hydrochloric acid -> Zinc chloride + Hydrogen
Zn(s)
+
2HCl (aq)
->
ZnCl2 (aq)
+
H2(g)
3
...
kcsepdf
...
ke
Fe(s)
+ 2HCl (aq)
->
FeCl2 (aq)
+ H2(g)
4
...
Magnesium + Sulphuric (VI) acid -> Magnesium sulphate (VI) + Hydrogen
Mg(s)
+ H2SO4 (aq) ->
MgSO4 (aq)
+ H2(g)
6
...
Iron + Sulphuric (VI) acid -> Iron (II) sulphate (VI) + Hydrogen Fe(s)
+
H2SO4 (aq) ->
FeSO4 (aq)
+
H2(g)
8
...
Reaction of metal carbonates and hydrogen carbonates with mineral acids
...

Metal carbonate + Acid -> Salt + Water+ Carbon(IV)oxide gas
Metal hydrogen carbonate + Acid -> Salt + Water
+ Carbon (IV) oxide gas
Experiment: reaction of metal carbonates and hydrogen carbonates with mineral
acids
...
Add half spatula full of
sodium carbonate
...
Record the observations made
...

(b)Repeat the procedure in (a) above using Zinc carbonate, Calcium carbonate, copper
carbonate, sodium hydrogen carbonate, Potassium hydrogen carbonate in place of
Sodium carbonate
...

Set up of apparatus
Acid

Lime water
Sodium carbonate

Sample observations
(i) effervescence/bubbles produced/fizzing in all cases
...

(iii) Gas produced forms a white precipitate with lime water
...
Carbon (IV) oxide gas is a colourless gas that extinguishes a
burning splint
...

Chemical equations
1
...
Calcium carbonate +Hydrochloric acid -> Calcium chloride + Carbon (IV)
Oxide+ Water
CaCO3(s)
+
2HCl (aq)
->
CaCl2 (aq)
+ H2O(g) + CO2 (g)
3
...
Copper carbonate +Hydrochloric acid ->Copper (II) chloride + Carbon (IV)
Oxide+ Water
CuCO3(s)
+
2HCl (aq)
->
CuCl2 (aq)
+ H2O (g) + CO2 (g)
5
...
Zinc carbonate +Sulphuric (VI) acid ->Zinc sulphate (VI) + Carbon
(IV) Oxide+ Water
ZnCO3(s)
+ H2SO4 (aq) -> ZnSO4 (aq) + H2O (g) + CO2 (g)
7
...
Potassium hydrogen carbonate +Sulphuric (VI) acid ->Potassium sulphate (VI)
+ Carbon (IV) Oxide+ Water
KHCO3(s) + H2SO4 (aq) -> K2SO4 (aq) + H2O (g) + CO2 (g)
9
...
Sodium hydrogen carbonate +Hydrochloric acid ->Sodium chloride + Carbon
(IV) Oxide+ Water
NaHCO3(s) + HCl (aq)
-> NaCl (aq) + H2O (g) + CO2 (g)
3
...
The reaction of an acid with
metal oxides/hydroxides (bases) to salt and water only is called neutralization reaction
...
The colour of the indicator
changes when all the acid has reacted with the soluble solution of the alkali (metal
oxides/ hydroxides)
...
The excess acid is then
filtered off
...

(i)Place about 5cm3 of dilute hydrochloric acid in a boiling tube
...
Using a dropper/teat pipette, add dilute sodium hydroxide
dropwise until there is a colour change
...
(iii)Repeat the procedure with potassium hydroxide instead of sodium
hydroxide
...

Explanation
Bases/alkalis neutralize acids
...
A suitable
indicator like phenolphthalein change colour to pink, when all the acid has been
neutralized by the bases/alkalis
...

Chemical equation
Sodium oxide + Hydrochloric acid -> Sodium chloride + Water
Na2O(s) +
HCl
->
NaCl(aq)
+ H2O(l)
Potassium oxide + Hydrochloric acid -> Potassium chloride + Water
K2O(s)
+
HCl
->
KCl(aq)
+ H2O(l)
Sodium hydroxide + Hydrochloric acid -> Sodium chloride + Water
NaOH(s)
+
HCl
->
NaCl(aq)
+ H2O(l)
Ammonia solution + Hydrochloric acid -> Ammonium chloride + Water
NH4OH(s) +
HCl
->
NH4Cl (aq)
+ H2O (l)
Potassium hydroxide + Hydrochloric acid -> Potassium chloride + Water
KOH(s)
+
HCl
->
KCl(aq)
+ H2O(l)
Sodium hydroxide + sulphuric (VI)acid -> Sodium sulphate(VI) + Water
2NaOH(s)
+
H2SO4
->
Na2SO4 (aq)
+ 2H2O (l)
Potassium hydroxide + sulphuric (VI) acid -> Potassium sulphate (VI) + Water
2KOH(s)
+
H2SO4
->
K2SO4 (aq)
+ 2H2O (l)
Ammonia solution + sulphuric (VI) acid -> Ammonium sulphate (VI) + Water
2NH4OH(s)
+
H2SO4
-> (NH4)2SO4 (aq)
+ 2H2O (l)
Magnesium hydroxide + sulphuric (VI) acid -> Magnesium sulphate (VI) + Water
Mg (OH)2(s) + H2SO4 -> MgSO4 (aq) + 2H2O(l) Magnesium hydroxide +
Hydrochloric acid -> Magnesium chloride + Water
Mg (OH)2(s)
+
HCl(aq)
->
MgCl2 (aq)
+ 2H2O(l)



---