Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
Calculate the atom economy for making hydrogen
by reacting zinc with hydrochloric acid:
Concentration of a solution
is the amount of solute per
volume of solution
Zn + 2HCl → ZnCl2 + H2
Atom economy = 2∕138 × 100
= 2∕138 × 100 = 1
...
5 + 35
...
It is not always
possible to obtain
the calculated
amount of a
product
Percentage yield is
comparing the
amount of product
obtained as a
percentage of the
maximum
theoretical amount
The reaction may not go to completion because it is
reversible
...
Some of the reactants may react in ways different to
the expected reaction
...
theoretical mass
What is the concentration of a solution that has 35
...
5dm3 of solution?
amount (mol)
volume (dm3)
35/0
...
It decomposes to make calcium oxide
and carbon dioxide
...
Yield is the
amount of
product
obtained
High atom economy is
important or sustainable
development and economic
reasons
Atom economy = Relative formula mass of desired product from equation x 100
Sum of relative formula mass of all reactants from equation
Titration
A measure of the amount
of starting materials that
end up as useful products
If the volumes of
two solutions that
react completely
are known and the
concentrations of
one solution is
known, the
concentration of
the other solution
can be calculated
...
20cm3 of sulfuric acid to neutralise 24
...
50mol/dm3
...
5 mol/dm3 x (24/1000) dm3 = 0
...
20cm3 of sulfuric acid is
(0
...
006 mol of sulfuric acid
Calculate the concentration of sulfuric acid in mol/ dm3
0
...
2) dm3 =0
...
A maximum theoretical
mass of 10g for sodium chloride was
calculated, but the actual yield was
only 8g
...
Percentage yield = 8/10 x 100 =80%
Calculate the concentration of sulfuric acid in
g/ dm3:
H2SO4 = (2x1) + 32 + (4x16) = 98g
0
...
2g/dm3
The volume of one mole of
any gas at room temperature
and pressure (20°C and 1
atmospheric pressure) is 24
dm3
No
...
6 g of
butane (C4H10) gas at RTP?
6g of a hydrocarbon gas had a volume of 4
...
Calculate its molecular mass
...
8/24 = 0
...
6/58 = 0
...
2 = 30
Volume = 0
...
8 dm3
If 6g = 0
...
0g of
solute in 0
...
5 = 70 g/dm3
Zn + 2HCl → ZnCl2 + H2
Atom economy = 2∕138 × 100
= 2∕138 × 100 = 1
...
5 + 35
...
Percentage yield
It is not always
possible to obtain
the calculated
amount of a
product
If the volumes of
two solutions that
react completely
are known and the
concentrations of
one solution is
known, the
concentration of
the other solution
can be calculated
...
It decomposes to make calcium oxide
and carbon dioxide
...
CaCO3 → CaO + CO2
Mr of CaCO3 = 40 + 12 + (16x3) = 100
Mr of CaO = 40 + 16 = 56
100g of CaCO3 would make 56 g of CaO
So 200g would make 112g
2NaOH(aq) + H2SO4(aq)→ Na2S04(aq) + 2H2O(l)
Using concentrations of
solutions in mol/dm3
(HT only, chemistry only)
Calculate the concentration of the sulfuric acid in mol/dm3:
0
...
012 mol of NaOH
The equation shows that 2 mol of NaOH reacts with 1 mol of
H2SO4, so the number of moles in 12
...
012/2) = 0
...
006 mol x (1000/12
...
49mol/dm3
Use of amount of substance in
relation to volumes of gases
(HT only, chemistry only)
The reaction may not go to completion because it is
reversible
...
A piece of sodium metal is heated in
chlorine gas
...
Calculate the percentage yield
...
49 x 98g = 48
...
% Yield = Mass of product made x 100
Max
...
20cm3 of sulfuric acid to neutralise 24
...
50mol/dm3
...
of moles of gas = vol of gas (dm3)
24dm3
What is the volume of 11
...
8 dm 3
...
Mr : (4 x 12) + (10 x 1) = 58
1 mole = 24 dm3, so 4
...
2 mol
11
...
20 mol
Mr = 6 / 0
...
20 x 24 = 4
...
2 mol, 1 mol equals 30 g
better hope – brighter future
A measure of the amount
of starting materials that
end up as useful products
Calculate the atom economy for making hydrogen
by reacting zinc with hydrochloric acid:
This method is unlikely to be chosen as it has a
low atom economy
...
Some of the product may be lost when it is separated
from the reaction mixture
...
Equation:
It takes 12
...
00cm3 of
sodium hydroxide solution, which has a concentration of
0
...
Calculate the concentration of the sulfuric acid in mol/dm3:
0
...
012 mol of NaOH
The equation shows that 2 mol of NaOH reacts with 1 mol of
H2SO4, so the number of moles in 12
...
012/2) = 0
...
006 mol x (1000/12
...
49mol/dm3
Percentage yield
Percentage yield is
comparing the
amount of product
obtained as a
percentage of the
maximum
theoretical amount
2NaOH(aq) + H2SO4(aq)→ Na2S04(aq) + 2H2O(l)
Using concentrations of
solutions in mol/dm3
(HT only, chemistry only)
HT only:
200g of calcium carbonate is heated
...
Calculate the theoretical mass of calcium oxide made
...
5 = 70 g/dm3
Titration
Atom economy = 2∕138 × 100
= 2∕138 × 100 = 1
...
5 + 35
...
0g of
solute in 0
...
A maximum theoretical mass
of 10g for sodium chloride was calculated,
but the actual yield was only 8g
...
Calculate the concentration of sulfuric acid in
g/ dm3:
H2SO4 = (2x1) + 32 + (4x16) = 98g
0
...
2g/dm3
No
...
6 g of
butane (C4H10) gas at RTP?
6g of a hydrocarbon gas had a volume of 4
...
Calculate its molecular mass
...
8/24 = 0
...
0g of
solute in 0
...
20cm3 of sulfuric acid to neutralise 24
...
50mol/dm3
...
It decomposes to make calcium oxide
and carbon dioxide
...
Use of amount of substance in
relation to volumes of gases
(HT only, chemistry only)
Equal amounts of
moles or gases occupy
the same volume
under the same
conditions of
temperature and
pressure
Yield is the
amount of
product
obtained
Percentage yield is
comparing the
amount of product
obtained as a
percentage of the
maximum
theoretical amount
2NaOH(aq) + H2SO4(aq)→ Na2S04(aq) + 2H2O(l)
Using concentrations of
solutions in mol/dm3
(HT only, chemistry only)
Equation:
A piece of sodium metal is heated in
chlorine gas
...
Calculate the percentage yield
...
6 g of
butane (C4H10) gas at RTP?
better hope – brighter future
Calculate the concentration of sulfuric acid in
g/ dm3:
Equation:
6g of a hydrocarbon gas had a volume of 4
...
Calculate its molecular mass
...
This displaces hydrogen as a gas while the metal ions are
left in the solution
...
The half-equation for iron (II) is:
Fe → Fe2+ + 2e-
Reactions of acids
and metals
The half-equation for copper (II) ions is:
Cu2+ + 2e- → Cu
Acid name
Salt name
Hydrochloric
acid
Chloride
Sulfuric acid
Sulfate
Nitric acid
metal + acid → metal salt
+ hydrogen
Reactions of
acids
Oxidation and
reduction in terms of
electrons (HT ONLY)
Neutralisation of acids
and salt production
Reactivity of
metals
calcium carbonate + sulfuric acid → calcium sulfate, + carbon dioxide + water
Neutralisation
The reactivity series
Metal
oxides
Metals and
oxygen
Metals react with
oxygen to form metal
oxides
magnesium + oxygen → magnesium oxide
2Mg
+ O2 →
2MgO
Reduction
This is when oxygen is
removed from a
compound during a
reaction
e
...
metal oxides reacting with hydrogen,
extracting low reactivity metals
Oxidation
This is when oxygen is
gained by a compound
during a reaction
Extraction using carbon
Metals less reactive than
carbon can be extracted
from their oxides by
reduction
...
g
...
A base is a substance that
neutralises an acid e
...
a soluble
metal hydroxide or a metal oxide
...
g
...
They can be mined
from the ground
...
Copper does not
react with acid
...
Carbon and
hydrogen
Carbon and hydrogen
are non-metals but are
included in the
reactivity series
These two non-metals are
included in the reactivity series as
they can be used to extract some
metals from their ores, depending
on their reactivity
...
better hope – brighter future
Silver nitrate + Sodium chloride →
Sodium nitrate + Silver chloride
HT ONLY: Reactions between metals and acids are redox reactions as the metal donates
electrons to the hydrogen ions
...
Oxidation Is Loss (of electrons) Reduction Is Gain (of electrons)
Ionic half equations (HT only)
metal + acid → metal salt
+ hydrogen
For example:
The ionic equation for the reaction
between iron and copper (II) ions is:
Fe + Cu2+ → Fe2+ + Cu
Ionic half
equations show
what happens
to each of the
reactants during
reactions
Acids react with some metals to
produce salts and hydrogen
...
g
...
A base is a substance that
neutralises an acid e
...
a soluble
metal hydroxide or a metal oxide
...
g
...
Extraction of
metals and
reduction
Group 1 metals
Group 2 metals
sodium hydroxide + hydrochloric acid → sodium chloride + water
Acids can
be
neutralised
by alkalis
and bases
zinc + sulfuric acid → zinc sulfate + hydrogen
AQA Chemical
Changes 1
Neutralisation of acids
and salt production
Sulfuric acid
magnesium + hydrochloric acid → magnesium chloride + hydrogen
e
...
metals reacting with oxygen, rusting of
iron
Zinc, iron and
copper
For example:
zinc oxide + carbon → zinc + carbon dioxide
Unreactive metals, such as gold, are found in
the Earth as the metal itself
...
Reactions get more
vigorous as you go down
the group
Reactions get more
vigorous as you go down
the group
Do not react with water
Observable reactions
include fizzing and
temperature increases
Do not react with water
Zinc and iron react slowly
with acid
...
The reactivity of a
metal is related to its
tendency to form
positive ions
The reactivity series arranges
metals in order of their reactivity
(their tendency to form positive
ions)
...
A more reactive metal
can displace a less
reactive metal from a
compound
...
This displaces hydrogen as a gas while the metal ions are
left in the solution
...
The half-equation for iron (II) is:
Fe → Fe2+ + 2eThe half-equation for copper (II) ions is:
Cu2+ + 2e- → Cu
Acid name
Salt name
Reactions of
acids
Oxidation and
reduction in terms of
electrons (HT ONLY)
Extraction of
metals and
reduction
AQA Chemical
Changes 1
Neutralisation of acids
and salt production
Reactivity of
metals
sodium hydroxide + hydrochloric acid → sodium chloride + water
calcium carbonate + sulfuric acid → calcium sulfate, + carbon dioxide + water
An alkali is a soluble base e
...
metal
hydroxide
...
g
...
For example:
zinc oxide + carbon → zinc + carbon dioxide
Reactions of acids
and metals
The reactivity series
Metal
oxides
Group 1 metals
Reactions get more
vigorous as you go down
the group
Group 2 metals
Observable reactions
include fizzing and
temperature increases
Zinc, iron and
copper
Zinc and iron react slowly
with acid
...
The reactivity of a
metal is related to its
tendency to form
positive ions
magnesium + oxygen → magnesium oxide
2Mg
+ O2 →
2MgO
e
...
metal oxides reacting with hydrogen,
extracting low reactivity metals
e
...
metals reacting with oxygen, rusting of
iron
Carbon and hydrogen
are non-metals but are
included in the
reactivity series
A more reactive metal
can displace a less
reactive metal from a
compound
...
This displaces hydrogen as a gas while the metal ions are
left in the solution
...
For example:
Reactions of acids
and metals
Acid name
Reactions of
acids
Oxidation and
reduction in terms of
electrons (HT ONLY)
Salt name
AQA Chemical
Changes 1
Neutralisation of acids
and salt production
Reactivity of
metals
Group 1 metals
Group 2 metals
Examples:
The reactivity series
An alkali is a
Extraction of
metals and
reduction
Metal
oxides
A base is a
magnesium + oxygen → magnesium oxide
2Mg
+ O2 →
2MgO
e
...
e
...
better hope – brighter future
Zinc, iron and
copper
Unreactive metals
At the
negative
electrode
Metal will be produced on the electrode
if it is less reactive than hydrogen
...
At the
positive
electrode
Oxygen is formed at positive electrode
...
Process of
electrolysis
Splitting up
using
electricity
When an ionic compound is melted or dissolved in
water, the ions are free to move
...
Passing an electric current though electrolytes causes
the ions to move to the electrodes
...
The negative electrode is called the cathode
...
Anions are negative ions and they move to the
positive anode
...
g
...
Hydrogen ion
concentration
As the pH decreases by one unit (becoming
a stronger acid), the hydrogen ion
concentration increases by a factor of 10
...
Filter off excess solid and then
crystallise to produce solid salts
...
In neutralisation reactions, hydrogen
ions react with hydroxide ions to
produce water:
H+ + OH- → H2O
Reactions of
acids
Lead ions Pb +
+
+
+
+
+
- -
Bromide ions Br Molten lead (II)
bromide
Titrations
(Chemistry
only)
Acids produce hydrogen ions (H+)
in aqueous solutions
...
This process is used when the metal is too
reactive to be extracted by reduction with
carbon
...
Example: aluminium is extracted in this
way
...
Fill the burette with acid and note the starting volume
...
3
...
Note
the final volume reading
...
Calculating the chemical quantities in
titrations involving concentrations in
mol/dm3 and in g/dm3
(HT ONLY):
2NaOH(aq) + H2SO4(aq)→ Na2S04(aq) +
2H2O(l)
Acids
Metals can be extracted from molten
compounds using electrolysis
...
Use the pipette to add 25 cm3 of alkali to a conical flask
and add a few drops of indicator
...
The pH scale and
neutralisation
Production of
soluble salts
AQA Chemical
Changes 2
Soluble salts
Soluble salts
Soluble salts can be made from reacting
acids with solid insoluble substances
(e
...
metals, metal oxides, hydroxides
and carbonates)
...
g
...
Extracting metals using
electrolysis
The ions discharged when an aqueous
solution is electrolysed using inert
electrodes depend on the relative
reactivity of the elements involved
...
20cm3 of sulfuric acid to neutralise
24
...
50mol/dm3
...
5 mol/dm3 x (24/1000) dm3 = 0
...
20cm3 of sulfuric acid is (0
...
006 mol of sulfuric acid
Calculate the concentration of sulfuric acid in
mol/ dm3
0
...
2) dm3 =0
...
49 x 98g = 48
...
Metal will be produced on the electrode
if it is less reactive than hydrogen
...
Oxygen is formed at positive electrode
...
As the pH decreases by one unit (becoming
a stronger acid), the hydrogen ion
concentration increases by a factor of 10
...
In neutralisation reactions, hydrogen
ions react with hydroxide ions to
produce water:
H+ + OH- → H2O
Cations
Anions
Cations are positive ions and they move to the
negative cathode
...
AQA Chemical
Changes 2
Reactions of
acids
Lead ions Pb +
+
+
+
This process is used when the metal is too
reactive to be extracted by reduction with
carbon
...
Example: aluminium is extracted in this
way
...
Bromide ions Br Molten lead (II)
bromide
Higher tier: You can display what is happening
at each electrode using half-equations:
At the cathode: Pb2+ + 2e- → Pb
At the anode: 2Br- → Br2 + 2e-
1
...
Titrations
(Chemistry
only)
2
...
Slowly add the acid from the burette to the alkali in the
conical flask, swirling to mix
...
Stop adding the acid when the end-point is reached (the
appropriate colour change in the indicator happens)
...
Repeat steps 1 to 3 until you get
consistent readings
...
Filter off excess solid and then
crystallise to produce solid salts
...
The negative electrode is called the cathode
...
g
...
Anode
Cathode
Electrolysis
Strong and weak acids
(HT ONLY)
Only partially ionised in aqueous solutions
e
...
ethanoic acid, citric acid
...
These are then able
to conduct electricity and are called electrolytes
...
_
Electrolysis of aqueous solutions
Completely ionised in aqueous solutions
e
...
hydrochloric, nitric and sulfuric acids
...
Aqueous solutions of alkalis
contain hydroxide ions (OH-)
...
20cm3 of sulfuric acid to neutralise
24
...
50mol/dm3
...
5 mol/dm3 x (24/1000) dm3 = 0
...
20cm3 of sulfuric acid is (0
...
006 mol of sulfuric acid
Calculate the concentration of sulfuric acid in
mol/ dm3
0
...
2) dm3 =0
...
49 x 98g = 48
...
When an ionic compound is melted or dissolved in
water, the ions are free to move
...
Passing an electric current though electrolytes causes
the ions to move to the electrodes
...
The negative electrode is called the cathode
...
Anions are negative ions and they move to the
positive anode
...
In neutralisation reactions,
Reactions of
acids
Lead ions Pb +
+
+
+
+
+
- -
Bromide ions Br Molten lead (II)
bromide
Higher tier: You can display what is happening
at each electrode using half-equations:
At the cathode:
At the anode:
1
...
Fill the burette with acid and note the starting volume
...
3
...
Note
the final volume reading
...
The pH scale and
neutralisation
Add the solid to the acid until no more
dissolves
...
AQA Chemical
Changes 2
Soluble salts
Soluble salts can be made from reacting
acids with solid insoluble substances
(e
...
metals, metal oxides, hydroxides
and carbonates)
...
g
...
+
Electrolysis
Electrolysis of aqueous solutions
Completely ionised in aqueous solutions
e
...
hydrochloric, nitric and sulfuric acids
...
Example: aluminium is extracted in this
way
...
Aqueous solutions of alkalis
contain hydroxide ions (OH-)
...
20cm3 of sulfuric acid to neutralise
24
...
50mol/dm3
...
5 mol/dm3 x (24/1000) dm3 = 0
...
20cm3 of sulfuric acid is
Calculate the concentration of sulfuric acid in
mol/ dm3
Calculate the concentration of sulfuric acid in
g/ dm3
The ions discharged when an aqueous
solution is electrolysed using inert
electrodes depend on the relative
reactivity of the elements involved
...
Titrations
(Chemistry
only)
2
...
20cm3 of sulfuric acid to neutralise
24
...
50mol/dm3
...
Simple cell
Calculate the overall energy change for the
forward reaction
N2 + 3H2 ⇌ 2NH3
Make a simple cell by
connecting two different
metals in contact with an
electrolyte
Batteries
Energy needed to break existing
bonds is greater than the
energy released making new
bonds
...
Non-rechargeable
cells
Endothermic
Energy released making new
bonds is greater than the
energy taken in breaking
existing bonds
...
Endothermic
Making bonds in products
The energy
change of
reactions
(HT only)
•
•
Disadvantages:
Hydrogen is highly flammable
Hydrogen is difficult to store
Fuel cells (Chemistry only)
Alkaline
batteries
Rechargeable
batteries
better hope – brighter future
Exothermic
Endothermic process
Overall energy change
of a reaction
Breaking bonds in reactants
Positive electrode:
O2 (g) + 2H2O (l) + 4e- → 4OH- (aq)
Word equation:
Activation energy
Reaction
profiles
Endothermic
Energy is taken in from the
surroundings so the
temperature of the
surroundings decreases
Chemical reactions only
happen when particles
collide with sufficient
energy
The minimum amount
of energy that colliding
particles must have in
order to react is called
the activation energy
...
As the
reactants form products, energy
is transferred from the
surroundings to the reaction
mixture
...
Products are at a lower energy
level than the reactants
...
The temperature
of the surroundings increases
because energy is released
during the reaction
...
Energy needed to break existing
bonds is greater than the
energy released making new
bonds
...
Word equation:
Symbol equation:
hydrogen + oxygen → water
2H2 + O2 → 2H2O
Advantages:
No pollutants produced
Can be a range of sizes
•
•
Disadvantages:
Hydrogen is highly flammable
Hydrogen is difficult to store
Fuel cells (Chemistry only)
AQA GCSE
Energy changes
Cells and batteries
(Chemistry only)
Make a simple cell by
connecting two different
metals in contact with an
electrolyte
Consist of two or more
cells connected together
in series to provide a
greater voltage
...
Alkaline
batteries
Bond breaking: 945 + (3 x 436) = 945 + 1308 =
2253 kJ/mol
Bond making: 6 x 391 = 2346 kJ/mol
Positive electrode:
O2 (g) + 2H2O (l) + 4e- → 4OH- (aq)
Can be recharged
because the chemical
reactions are reversed
when an external
electrical current is
supplied
Rechargeable
batteries
better hope – brighter future
Reaction
profiles
Chemical reactions only
happen when particles
collide with sufficient
energy
The minimum amount
of energy that colliding
particles must have in
order to react is called
the activation energy
...
As the
reactants form products, energy
is transferred from the
surroundings to the reaction
mixture
...
Products are at a lower energy
level than the reactants
...
The temperature
of the surroundings increases
because energy is released
during the reaction
...
Bond energy calculation
Bond energies (in kJ/mol): H-H 436, H-N 391,
N≡N 945
Bond breaking: 945 + (3 x 436) = 945 + 1308 =
2253 kJ/mol
Bond making: 6 x 391 = 2346 kJ/mol
Overall energy change =
Therefore reaction is exothermic overall
...
AQA GCSE
Energy changes
Cells and batteries
(Chemistry only)
Rechargeable cells
Overall energy change
of a reaction
Making bonds in products
The energy
change of
reactions
(HT only)
Increase the
voltage by
increasing the
reactivity
difference
between the
two metals
...
Products are at a higher energy
level than the reactants
...
The temperature of the
surroundings decreases because
energy is taken in during the
reaction
...
Enzymes
These are biological
catalysts
...
Rate of
reaction
Catalysts provide a
different reaction pathway
where reactants do not
require as much energy to
react when they collide
...
Rate of
chemical
reaction
AQA GCSE
The rate and
extent of
chemical change
Temperature
The higher the temperature, the quicker the
rate of reaction
...
Surface area
The larger the surface area of a reactant solid,
the quicker the rate of reaction
...
Collision theory and
activation energy
Collision theory
Chemical reactions can
only occur when reacting
particles collide with each
other with sufficient
energy
...
Activation
energy
This is the minimum
amount of energy
colliding particles in a
reaction need in order to
react
...
Reversible reactions
and dynamic
equilibrium
Reversible reactions
In some chemical reactions, the
products can react again to re-form
the reactants
...
Equilibrium
in reversible
reactions
Energy changes and reversible reactions
If one direction of a reversible reaction is exothermic,
the opposite direction is endothermic
...
For example:
Hydrated copper
sulfate
When a reversible reaction occurs
in apparatus which prevents the
escape of reactants and products,
equilibrium is reached when the
forward and reverse reactions
occur exactly at the same rate
...
Changing
concentration
If the concentration of a reactant is increased, more products
will be formed
...
Changing
temperature
If the temperature of a system at equilibrium is increased:
- Exothermic reaction = products decrease
- Endothermic reaction = products increase
Changing
pressure
(gaseous
reactions)
For a gaseous system at equilibrium:
- Pressure increase = equilibrium position shifts to side of
equation with smaller number of molecules
...
Quantity
Unit
Rate = quantity of product formed
time taken
Calculating rates of reactions
Mass
Rate of
reaction
Volume
Rate of
reaction
These are biological
catalysts
...
Catalysts
A catalyst changes the rate
of a chemical reaction but
is not used in the reaction
...
Factors affecting the rate of reaction
The higher the temperature, the quicker the
rate of reaction
...
AQA GCSE
The rate and
extent of
chemical change
The higher the concentration, the quicker the
rate of reaction
...
When gases react, the higher the pressure
upon them, the quicker the rate of reaction
...
Increasing the temperature increases
the frequency of collisions and makes
the collisions more energetic,
therefore increasing the rate of
reaction
...
Increasing the concentration, pressure
(gases) and surface area (solids) of
reactions increases the frequency of
collisions, therefore increasing the rate
of reaction
...
The relative amounts of reactants and
products at equilibrium depend on the
conditions of the reaction
...
Energy changes and reversible reactions
If one direction of a reversible reaction is exothermic,
the opposite direction is endothermic
...
For example:
Hydrated copper
sulfate
endothermic
exothermic
Anhydrous copper + Water
sulfate
better hope – brighter future
States that when a system experiences a disturbance (change in
condition), it will respond to restore a new equilibrium state
...
If the concentration of a product is decreased, more reactants
will react
...
- Pressure decrease = equilibrium position shifts to side of
equation with larger number of molecules
...
Factors affecting the rate of reaction
Factors affecting rates
Rate = quantity of reactant used
time taken
Rate of
chemical
reaction
AQA GCSE
The rate and
extent of
chemical change
Temperature
Concentration
Surface area
Pressure (of gases)
Collision theory and
activation energy
Collision theory
Reversible reactions
and dynamic
equilibrium
How do
they work?
Activation
energy
Reversible reactions
Changing conditions
and equilibrium (HT)
Equilibrium
Reversible
reactions
Representing
reversible
reactions
The direction
The direction of reversible reactions
can be changed by changing
conditions:
heat
A + B
C + D
cool
The relative amounts of reactants and
products at equilibrium depend on the
conditions of the reaction
...
The same
amount of energy is transferred in each case
...
endothermic
exothermic
Anhydrous copper + Water
sulfate
better hope – brighter future
Le Chatelier’s
Principles
Changing
concentration
Changing
temperature
Changing
pressure
(gaseous
reactions)
Increasing the temperature increases
the frequency of collisions and makes
the collisions more energetic,
therefore increasing the rate of
reaction
...
Factors affecting the rate of reaction
Quantity
Unit
Calculating rates of reactions
Grams (g)
cm3
Rate of
reaction
Grams per cm3 (g/cm3)
HT: moles per second
(mol/s)
Catalysts
Catalyst
Enzymes
If a catalyst is used
in a reaction, it is
not shown in the
word equation
...
The direction
Equilibrium
in reversible
reactions
Energy changes and reversible reactions
If one direction of a reversible reaction is exothermic,
the opposite direction is endothermic
...
For example:
Hydrated copper
sulfate
endothermic
exothermic
Anhydrous copper + Water
sulfate
better hope – brighter future
Le Chatelier’s
Principles