Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

PARTICLES
Ch
...

Explain why the ring was formed nearer the hydrochloric acid end of the tube
• Ammonia particles are lighter than hydrogen chloride particles and so move faster
...

What effect do you think using hydrogen bromide would have on the experiment
• The heavier hydrogen bromide particles would move more slowly than the hydrogen chloride particles, and so the
ring would form even closer to the hydrobromic acid end than it was to the hydrochloric acid end
...

Would you expect there to be any differences between the chemical properties of the isotopes?
• No - chemical properties are governed by electrons; same number in each isotope
...
3,4
Metallic

Strong electrostatic attraction force between the sea of negatively charged delocalized electrons and
positive metal ions
Ionic
Strong electrostatic attraction force between positive metal ions and negative non metal ions
Covalent
Strong electrostatic attraction force between the negatively charged bond pair electrons and
positively charge nuclei of the bonded atoms
Intermolecular Weak electrostatic attraction force between molecules
What is an alloy
• A mixture of two or more metals
Explain how the structures of copper and brass relate to how hard they are
• Copper is ductile and malleable
...
The zinc ions will distort the regular layers of atoms and the atoms will not
slide over one another easily, more force is needed to overcome the bond
...
The
metallic bond in Al is the strongest among all
• The most heat is needed to break the bond and separate the aluminium ions
Why graphite can conduct electricity but diamond cannot
• Each carbon atom in graphite is bonded to 3 carbon atoms by forming 3 covalent bonds
• The remaining electron is hence a delocalized electron, which can conduct electricity
• Each carbon atom in diamond is bonded to 4 carbon atoms by forming 4 covalent bonds
• There is no delocalized electron and it cannot conduct electricity
Which one has a higher melting point? Potassium chloride or hydrogen chloride?
• Potassium has a higher melting point
• KCl has a giant ionic structure
...
A lot of heat
is needed to overcome the bond to separate the ions
• HCl has a simple molecular structure
...
Little heat is
needed to overcome the weak intermolecular force to separate the molecules
...
 of  H2  

Vol
...
6
Draw a graph
Excess and equal masses of marble react with same
limited volume 0
...
0M HCl

Why is the initial rate of the experiment highest
• At the very beginning of the reaction
...

Numbers of acid particles are greatest at the beginning of the reaction before any get used up
• therefore the greatest number of collisions per second and the fastest reaction is at the beginning
...
A larger proportion of collisions can overcome the activation energy barrier of the
reaction
...

• Catalysts provide an alternative route for the reaction with a lower activation energy and allows reactant particles
to react with smaller amount of energy
Reasons for percentage yield to be less than calculated value
• Reactants not pure
• Some solution left in container when transferred
• It is a reversible reaction and not all reactants are turned into products
Equation for mixing sodium thiosulphate solution with dilute hydrochloric acid
• Na2S2O3+2HClè 2NaCl+S+SO2+H2O
Explain why the mixture became cloudy
• Sulphur is formed and it is insoluble in water, causing the mixture to turn cloudy yellow

ESSENTIAL BACKGROUND CHEMISTRY
Ch
...

• It sinks the flame preventing oxygen getting at the fuel
...

• When the top is released, the pressure drops to atmospheric
...

Write a chemical equation for the reaction between carbon dioxide and limewater
• CO2(g)+Ca(OH)2(aq)èH2O(l)+CaCO3(s)
State and explain what would happen when excess carbon dioxide is passed into the milky limewater with an
aid of an equation
• Insoluble calcium carbonate precipitate reacts with the excess CO2 and water to form soluble calcium
hydrogencarbonate
• CaCO3(s)+ CO2(g)+ H2O(l)èCa(HCO3)2
Explain why limestone buildings are damaged by acid rain
• Limestone is mainly consist of calcium carbonate and acid rain is a weak acid, which will react with CaCO3 to
form a salt, CO2 and water
...

How to avoid sucking back
• The delivery tube should be removed from water before heating is stopped
...
8,9
Fe(s)+CuSO4(aq)è FeSO4(aq)+Cu(s)
Write down ionic equation of the experiment
• Fe(s)+Cu2+ (aq)è Fe2+(aq)+Cu(s)
What does this tell you about the position of copper and iron in the reactivity series?
• Iron is above copper because it displaces copper from its solution and loses electrons to form Fe2+ ions
Observations
• grey iron filings become coated with brown solid
• solution fades from blue very pale green
Explain why the aluminum hardly reacts with dilute acid in the cold but reacts vigorously after gentle heating
• Aluminum is covered by a very thin, but very strong, layer of aluminum oxide which prevents the acid getting at
the aluminum underneath
...
The aluminum then shows its true reactivity, and
produces a vigorous reaction
...
What is the meaning of this statement?
• Each carbonic acid molecule, when dissolves in water, it will ionize to give 2H+ ions
...
10
Making insoluble salts BY PRECIPITATION
1
...
Filter the mixture and collect the precipitate as residue
3
...
Dry with filter paper
Making soluble slats BY ADDING AN EXCESS OF AN INSOLUBLE SOLID TO AN ACID
1
...
Filter off the excess solid
3
...
Leave it to cool down and evaporate slowly at room temperature
5
...
Wash with a little of cold distilled water
7
...
Add the potassium hydroxide solution and nitric acid to a burette and conical flask respectively
2
...
Titrate to the end point when a sharp color change is observed
4
...
Heat to concentrate the solution
6
...
Filter to collect the crystals
8
...
Dry with filter paper
Ch
...

Moisten the wire with concentrated hydrochloric acid, dip it into the solid, and
then back into flame
Add a few drops of dilute sodium hydroxide solution to aqueous sample in a
test tube
Observe the color of precipitate
Heat with sodium hydroxide solution
Test the gas formed with moist red litmus paper
Add dilute nitric acid
Test the gas formed with limewater
Add excess dilute HCL followed by chloride solution to aqueous sample
Add excess dilute HNO3 followed by silver nitrate solution
Why does we add dilute HNO3?
• To remove CO32- to ensure formation of ppt indicates presence of halide
Anhydrous copper(II) sulfate powder
Anhydrous cobalt chloride paper
Use a damp blue litmus paper

Li+
Na+
K+
Ca2+
Cu2+
Cu2+
Fe3+
Fe2+
NH4+

Red
Strong persistent orange
Lilac
Brick red
Bluish green
Blue [Cu(OH)2]
Orange brown [Fe(OH)3]
Dirty green [Fe(OH)2]
Turns moist red litmus paper
blue
...
Limewater turns
milky
SO42- White precipitate(ppt)
ClWhite ppt [AgCl]
BrCreamy pale yellow ppt
[AgBr]
IYellow ppt [AgI]
The powder turns from white to blue
The paper turns from blue to pink
Cl2
Turns blue litmus paper red
and then bleaches the litmus
paper

Ch
...
No room to share electrons to form covalent bonds and therefore
monatomic
...

• Unreactive because of the lack of possibility of forming covalent bonds or stable ions
...

• K atom is larger than Na atom
• the outermost electron of K is further from the attraction of the nucleus and so lost more easily
...

• F atom is smaller than Cl atom
• the attraction between incoming e- and the nucleus in F is stronger and has a higher tendency to accept electrons
Why does chlorine displaces bromine from potassium bromide solution
• Cl2(aq) + 2Br-(aq) ----> 2Cl-(aq) + Br2(aq)
• Chlorine removes an electron from a Br- ion and uses it to form Cl-
...
This happens because bromine is a smaller
atom than iodine and so an extra electron is closer to, and more attracted to, the bromine nucleus than it was to the
iodine nucleus
Function of chlorine in the reaction with the iodide ions
• It acts as the oxidizing agent because it removes electrons from iodide ions
Why is copper used for making pipes
It is a transition metal
It has a high boiling point and it lacks reactivity with water
COLORS
Cl2(aq)
Br2(aq)
I2(aq)

Pale green
Orange brown
Brown

F2
Cl2
Br2
I2
At2

Gas
Gas
Liquid
Solid
Solid

Gradual increase in mp and bp down the
group, because the larger the molecular
size, the stronger the intermolecular
forces hence more heat is needed to
overcome these forces
...
13

Why will the concentration of the solution stay the same
• For every copper ion that is deposited at the cathode, another one goes into solution as Cu2+ ions at the anode
...
14,15
C7H16+11O2è 7CO2+8H2O
Explain why this reaction is exothermic
Energy is needed to break the bonds in heptane and in oxygen
...
More energy is released when the new bonds are made than was used to break
the old ones
...
More heat is released to the surrounding to form the bond that is used to break AB bond
What does dynamic equilibrium mean?
The rate of forward reaction is the same as the rate of backward reaction
The concentration of reactants and products remain constant
Explain what is meant by the symbol ∆H
• ΔH shows the amount of heat evolved or absorbed during the reaction
...

A higher pressure favors the side with fewer moles of gas
Explain why enthalpy change of reaction is negative
The graph shows that a lower temperature leads to higher conversion to ammonia
...


Ch
...
450℃
Uses of ammonia
2
...
Making fertilizers
3
...
Making nitric acid
3
...

• A catalyst speeds up the forward and backward reactions by the same proportion, there is no shifting of the
equilibrium and thus the yield is unchanged
...
What effect does using one have on the cost of producing ammonia
...

H2S2O7(l) + H2O(l) è 2H2SO4(l)
Uses of sulfuric acid
1
...
Manufacture of detergents
3
...
Sterilising water
1
...
Soap making
drink
3
...
Making HCl
to make alumina
3
...
Making bleach
2NaOH(aq)+Cl2(g)èNaCl(aq)+NaOCl(aq)+H2O(l)

Why is it important that the liquid level in the left hand compartment of a diaphragm cell is higher than that in
the right hand one?
• That makes sure that the flow of liquid is always from left to right, preventing any of the sodium hydroxide
solution formed finding its way back to where chlorine is being produced
...

• As the hydrogen ions are discharged to give hydrogen gas, the equilibrium moves to the right to replace them (Le
Chatelier’s Principle), water continues to ionize to replenish the H+ ions
...

• There is therefore a build-up of sodium ions and hydroxide ions in the cathode compartment
...
Explain Why
...
Once the reaction starts, there is enough heat
produced to keep the catalyst hot
...
17
Suggest a method for manufacturing metal
K
Na
Ca
Mg
Electrolysis of its oxide

Al

Zn

Fe

Pb

Cu

Reduction of its oxide with carbon

Hg

Ag

Heating its
oxide

Why reactive metals wasn’t produced until the early nineteenth century
• Needed discovery of electricity
...

Why is it more expensive using electrolysis than carbon reduction method?
• Carbon is quite cheap
...

• A lot of electricity is needed to generate a high temperature to keep the electrolyte molten, thus it is expensive
Extraction of aluminium
Process
• Electrolysis of aluminium oxide dissolved in molten cryolite
Why is bauxite dissolved in molten cryolite
• Molten cryolite act as a solvent
• It decreases the operating current of the electrolysis, saving some energy cost
Why is it expensive to extract aluminium
• Large amount of electricity are needed to maintain a huge current which generates enough heat to keep the
electrolyte molten
• Oxygen is formed at the carbon anodes and the operating temperature is high, carbon anodes burn in the oxygen to
form CO2 and need regular replacements

Extraction of iron using a blast furnace
Process
Carbon in coke burns in air to produce heat to maintain the temperature of the furnace
C(s)+ O2(g) → CO2(g)
Forms carbon monoxide needed to reduce the iron oxide
CO2(g) + C(s) → 2CO(g)
Reduction of iron ore haematite
Fe2O3(s) +3CO(g) → 2Fe(l)+ 3CO2(g)
Fe2O3(s) +3C(s) → 2Fe(l)+ 3CO(g)
Limestone is calcium carbonate
...
Haematite
2
...
Limestone: Contains calcium carbonate to help remove acidic impurities SiO2 from the iron by reacting with
them to form molten slag
4
...

• Iron coated with zinc
...

• Zinc is more reactive than iron and so corrodes more easily
...
These electrons flow to the iron and prevent its ionization (which would lead to rusting)

Ch
...
Isomers have different bondings, thus they have different boiling points
Characteristics of homologues in the same homologous series
• Same functional group
• Same general formula
• Gradation in physical properties
Advantages and disadvantages of fermentation
• Fermentation uses renewable resources and gentle conditions are used
...
Water is still produced, but carbon
monoxide and carbon are produced instead of carbon dioxide
...

Explain why the incomplete combustion of hydrocarbons causes safety problems
• Incomplete combustion leads to formation of carbon monoxide which is very poisonous
...

• Cracking introduces C=C double bonds which are more reactive and therefore more useful
...
Smaller molecules aren't as strongly attracted to their neighbors as bigger ones (weaker intermolecular
attractions)
...

Explain why long string of carbon atoms hydrocarbon is good for using as a lubricant
• Oil with long carbon chain is very viscous and they can cling to moving parts of the engine, preventing damage
Explain why distillation is a good way to separate the liquids in crude oil
• The hydrocarbons all have different boiling points
• During distillation the oil is heated and the different hydrocarbons boil off at different temperatures
...
Polymerization is the joining of small
molecules to form large molecules
...
Polymerization usually joins alkenes to form alkane
• Cracking involves breaking single bonds between carbon atoms
...

Differences between condensation polymerization and addition polymerization
• AP: Monomers involved are unsaturated
CP: Monomers involved have functional groups that can react together
• AP: Monomers join together without losing any molecules
CP: Monomers join together by losing small molecules such as water
Explain why disposal of addition polymers is difficult
• They are inert due to the presence of strong C-C and C-H bonds
...

• When buried in landfills, it causes land pollution
...
22-26
What is RAM
• Relative atomic mass
...
It is measured
on a scale on which a carbon-12 atom has a mass of exactly 12 units
How to calculate heat evolved
• Heat evolved = mass of water x specific heat x temperature rise
...
𝑜𝑓  𝑚𝑜𝑙𝑒  𝑜𝑓  𝑁𝑎𝑂𝐻  𝑛𝑒𝑢𝑡𝑟𝑎𝑙𝑖𝑧𝑒𝑑
𝑁𝑜

---