AQA A Level Chemistry Paper 1 2022
Bronsted-Lowry acid - Answer a proton donor.
Bronsted-Lowry base - Answer proton acceptor
What is H3O+? - Answer hydronium ion
definition of pH - Answer -log10[H+]
How do you get [H+] from ph? - Answer 10^(-pH)
the ionic product of water - Answer [OH-][H+]
Is dissociation an endo or exothermic reaction? - Answer endothermic
Why is the concentration of water not included in Kw? - Answer The concentration of
water is so large and constant the equilibrium equation can be simplified
How does temperature affect Kw? - Answer The hotter the water is, the more
dissociated it is and the larger its Kw value.
What is the value of Kw at room temperature? - Answer 10^(-14)
what is a weak acid? - Answer An acid that partially dissociates in solution
What is a strong acid? - Answer an acid that fully dissociates in solution
What is Ka? - Answer ([H+][A-])/[HA]
What does a large Ka value mean? - Answer The larger ka the stronger the acid.
Ka= - Answer 10^-pKa
Definition of pKa - Answer -log10Ka
When you dissolve a weak monoprotic acid in solution what happens? - Answer [H+] is
always equal to [A-]
Ka= [H+]^2/[HA]
Concordant results - Answer Titres that are in agreement usually within 0.10cm3 of
each other
equivalence point - Answer At the equivalence point, the acid is just about neutralised
[OH-] = [H+]
How do you choose a good indicator for titrations? - Answer If the equivalence point is
within its ph range colour change
, AQA A Level Chemistry Paper 1 2022
What are two examples of good indicators for titrations? - Answer Phenolphthalein and
methyl orange
What ranges (and colour changes) does Phenolphthalein span over? - Answer
Phenolphthalein changes from colourless to pink from pH 8.3 to pH 10.
What ranges (and colour changes) does methyl orange span over? - Answer Methyl
orange changes colour from red to yellow between pH 3.1 and pH 4.4.
What would you use to find the equivalence point of a Weak Acid and Weak Base
reaction, and why? - Answer use a pH meter
It's hard to see the equivalence point as the change is so small (indicator not sensitive
enough)
what is a buffer solution? - Answer A solution that resists changes in pH when small
amounts of an acid or a base are added
Acidic buffer - Answer Weak acid and a salt of a weak acid (conjugate base)
What assumptions do you need to make when calculating the pH of a buffer? - Answer
That the salt is fully dissociated.
That the acid is pretty much un-ionised.
What does it do to assume that the salt is fully dissociated when calculating the pH of a
buffer? - Answer We assume the salt is fully dissociated, so [A-] is just the initial salt
concentration.
What does it do to assume that the acid is pretty much un-ionised when calculating the
pH of a buffer? - Answer We assume the [HA] is un-ionised, so that's just the initial acid
concentration.
[H+]=[A-] what does this assume? - Answer all the H+ has come from the acid
dissociating - water dissociation is negligble
What are the phases of halogens? - Answer Fluorine - gas.
Chlorine - gas.
Bromine - liquid.
Iodine - solid.
What's the trend going down group 7 for electronegativity? - Answer Electronegativity
decreases as you go down Group 7
What's the trend going down group 7 for boiling points? And why? - Answer Boiling
points increase down the group.
This is because elements have more electrons as you go down Group 7.
Bronsted-Lowry acid - Answer a proton donor.
Bronsted-Lowry base - Answer proton acceptor
What is H3O+? - Answer hydronium ion
definition of pH - Answer -log10[H+]
How do you get [H+] from ph? - Answer 10^(-pH)
the ionic product of water - Answer [OH-][H+]
Is dissociation an endo or exothermic reaction? - Answer endothermic
Why is the concentration of water not included in Kw? - Answer The concentration of
water is so large and constant the equilibrium equation can be simplified
How does temperature affect Kw? - Answer The hotter the water is, the more
dissociated it is and the larger its Kw value.
What is the value of Kw at room temperature? - Answer 10^(-14)
what is a weak acid? - Answer An acid that partially dissociates in solution
What is a strong acid? - Answer an acid that fully dissociates in solution
What is Ka? - Answer ([H+][A-])/[HA]
What does a large Ka value mean? - Answer The larger ka the stronger the acid.
Ka= - Answer 10^-pKa
Definition of pKa - Answer -log10Ka
When you dissolve a weak monoprotic acid in solution what happens? - Answer [H+] is
always equal to [A-]
Ka= [H+]^2/[HA]
Concordant results - Answer Titres that are in agreement usually within 0.10cm3 of
each other
equivalence point - Answer At the equivalence point, the acid is just about neutralised
[OH-] = [H+]
How do you choose a good indicator for titrations? - Answer If the equivalence point is
within its ph range colour change
, AQA A Level Chemistry Paper 1 2022
What are two examples of good indicators for titrations? - Answer Phenolphthalein and
methyl orange
What ranges (and colour changes) does Phenolphthalein span over? - Answer
Phenolphthalein changes from colourless to pink from pH 8.3 to pH 10.
What ranges (and colour changes) does methyl orange span over? - Answer Methyl
orange changes colour from red to yellow between pH 3.1 and pH 4.4.
What would you use to find the equivalence point of a Weak Acid and Weak Base
reaction, and why? - Answer use a pH meter
It's hard to see the equivalence point as the change is so small (indicator not sensitive
enough)
what is a buffer solution? - Answer A solution that resists changes in pH when small
amounts of an acid or a base are added
Acidic buffer - Answer Weak acid and a salt of a weak acid (conjugate base)
What assumptions do you need to make when calculating the pH of a buffer? - Answer
That the salt is fully dissociated.
That the acid is pretty much un-ionised.
What does it do to assume that the salt is fully dissociated when calculating the pH of a
buffer? - Answer We assume the salt is fully dissociated, so [A-] is just the initial salt
concentration.
What does it do to assume that the acid is pretty much un-ionised when calculating the
pH of a buffer? - Answer We assume the [HA] is un-ionised, so that's just the initial acid
concentration.
[H+]=[A-] what does this assume? - Answer all the H+ has come from the acid
dissociating - water dissociation is negligble
What are the phases of halogens? - Answer Fluorine - gas.
Chlorine - gas.
Bromine - liquid.
Iodine - solid.
What's the trend going down group 7 for electronegativity? - Answer Electronegativity
decreases as you go down Group 7
What's the trend going down group 7 for boiling points? And why? - Answer Boiling
points increase down the group.
This is because elements have more electrons as you go down Group 7.
