Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

AQA Physical Chemistry > Acids and Bases > Flashcards

Acids and Bases Flashcards

(78 cards)

Start Studying
1
Q

Define an acid

A

A proton (H+) donor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a monobasic acid?

A

For every 1 mole of acid, 1 mole of H+ is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a dibasic acid?

A

For every 1 mole of acid, 2 moles of H+ are produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a tribasic acid?

A

For every 1 mole of acid, 3 moles of H+ are produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define a base

A

A proton (H+) acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a monobasic base?

A

For every 1 mole of base, 1 mole of OH- is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a dibasic base?

A

For every 1 mole of base, 2 moles of OH- are produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a tribasic base?

A

For every 1 mole of base, 3 moles of OH- are produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are 3 examples of a strong acid?

A
  • HCl- HNO3- H2SO4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does a strong acid do?

A

Fully dissociates in solution to produce H+ (aq)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are 3 examples of a strong base?

A
  • NaOH- KOH- Ca(OH)2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does a strong base do?

A

Fully dissociates in solution to produce OH- (aq)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are 3 examples of a weak acid?

A
  • H3PO4- HF- CH3COOH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do weak acids do?

A
  • They do not fully dissociate in solution to produce H+- They exist in equilibrium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do weak bases do?

A
  • They do not fully dissociate in solution to produce OH_- They partially react with H2O to form OH- (aq)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are 2 examples of a weak base?

A
  • NH3- CH3NH2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do you find pH?

A

-log10[H+]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do you find [H+]?

A

10^-pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do you calculate the pH of a strong acid?

A
  • Because they fully dissociate there will be a ratio between [acid] and [H+] based on wether they are mono/di/tri basic- For a dibasic strong acid, if one mole of acid reacts then 2 moles of H+ will be produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How do you calculate the pH of a weak acid?

A
  • Ka is used- [H+] = (sqr root of) Ka x [HX]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do you calculate the pH of a strong base?

A
  • Kw is used- [H+] = kw/[OH-]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 3 steps to calculating the pH of a strong acid?

A

1 - Find the acid concentration2 - Use stoichiometry and knowledge of mono/di/tribasic acids to find concentration of hydrogen ions3 - Use -log (base 10) [H+]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the 3 steps to finding the concentration of a strong acid?

A

1 - Find the pH2 - Calculate [H+] using 10^-pH3 - Use stoichiometry to find [acid]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Ka?

A

The equilibrium constant of the dissociation of a weak acid, it is a quantitative measurement of the strength of a weak acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the difference between a large value of Ka and a small value of Ka?
The larger the value of Ka, the stronger the acid
26
Why is Ka used for weak acids?
Weak acids do not fully dissociate in solution (they exist in equilibrium)
27
What is the equation for the Ka of HX <=> H+ + X- ?
Ka = [H+][X-] / [HX]
28
What do you need to know to be able to calculate the pH of a weak acid?
1 - Ka value2 - Acid concentration
29
What do you need to know to be able to calculate the concentration of a weak acid?
- Ka value- pH
30
What is a base?
A proton acceptor
31
What is an alkali?
A type of soluble base that releases OH- ions in solution
32
What are the 4 types of base?
- Metal hydroxides- Ammonia- Metal oxides- Metal carbonates
33
Which bases are alkalis?
- Metal hydroxides- Ammonia
34
What are examples of metal hydroxides?
- NaOH- KOH- Ca(OH)2
35
What are examples of metal oxides?
- Na2O- K2O- MgO- CuO
36
What are examples of metal carbonates?
- Na2CO3- K2CO3- MgCO3- CaCO3
37
What do strong alkalis do?
Fully dissociate in solution
38
What do weak alkalis do?
Partially dissociate in solution
39
What is water?
Amphoteric (can act as an acid and as a base)
40
What is Kw?
The dissociation constant for the dissociation of water
41
What is Kw used for?
Calculating the pH of a strong base
42
What is the Kw equation?
Kw = [H+][OH-]
43
What is the Kw value for pure water at 298k at a pH of 7?
1 x 10^-14 mol^2dm^-6
44
What happens to Kw when you increase the temperature?
- Endothermic reaction is favoured- Equilibrium shifts to the right- Kw increases
45
What happens to Kw when you decrease the temperature?
- Exothermic reaction is favoured- Equilibrium shifts to the left- Kw decreases
46
What do you need to know to be able to calculate the pH of a strong base?
1 - Conc of a strong base2 - Kw = 1x10^-14 mol.dm^-3
47
What steps to you need to follow to calculate the pH of a strong base?
1 - Find [OH-]2 - Use kw expression to find [H+]3 - Use -log[H+]
48
What do you need to know in order to calculate the concentration of a strong base?
- Kw value- pH
49
How can you calculate pKa?
-logKa
50
How can you calculate Ka from pKa?
Ka = 10^ -pKa
51
What is the relative strength of an acid with a high pKa value?
Weaker acid
52
What is the relative strength of an acid with a high Ka value?
Stronger acid
53
What is the relative strength of an acid with a low pKa value?
Stronger acid
54
What is the relative strength of an acid with a low Ka value?
Weaker acid
55
How can you calculate pKw?
-logKw
56
How can you calculate Kw from pKw?
10^-pKw
57
What happens to pKw when Kw is increased?
pKw decreases
58
What happens to pKw when Kw is decreased?
pKw increases
59
What is a pH curve?
A titration using a pH probe to monitor changes in pH during the addition of a base (alkali) to an acid
60
What is the equivalence point?
The point at which the graph is vertical and therefore the point at which neutralisation happens
61
What can the equivalence point tell us?
The volume of base needed to neutralise acid
62
When carrying out a titration, what should you do near the equivalence point?
Use smaller increments
63
What three things can you read from any pH curve?
- [H+]- [OH-]- A suitable indicator
64
How can you calculate [H+] from a pH curve?
10^-pH
65
How can you calculate [OH-] from a pH curve?
Calculate [H+] then divide Kw by [H+]
66
How can you select an indicator for a pH curve?
Choosing an indicator with a pH range inside the equivalence region
67
What can you calculate from a weak acid, strong base pH curve?
The Ka for the weak acid- Find vol.base needed for neutralisation- Half volume- Find pH at half volume- pH = pKa- Ka = 10^-pKa
68
What is a buffer solution?
A buffer solution maintains an approximately constant pH despite the addition of water and small amounts of acid or base
69
What does an acid buffer contain?
A weak acid and the salt of the weak acid
70
How does an acid buffer oppose the change if the buffer is diluted?
- Adding water will decrease [H+]- Equilibrium shifts to the right to oppose the change - More acid dissociates to increase the [H+] to what is was before
71
How does an acid buffer oppose the change if alkali or base is added?
- Decreases [H+] by neutralisation- Equilibrium shifts to the right to oppose the change- More acid dissociates to increase the [H+] to what it was before
72
How does an acid buffer oppose the change if acid is added?
- Increases [H+]- Equilibrium shifts to the left to oppose the change- [H+] is decreased to what is was before - Conjugate base associates with H+ to form acid
73
What does a basic buffer contain?
A weak base and the salt of the weak base
74
How does a basic buffer oppose the change if water is added?
- Decrease [OH-] - Equilibrium shifts to the right to oppose the change- More base and water reacted together top form more OH- to maintain the pH
75
How does a basic buffer oppose the change if acid is added?
- [OH-] decreased because of neutralisation- Equilibrium shifts to the right to oppose the change and maintain [OH-]
76
How does a basic buffer oppose the change if alkali is added?
- Increase [OH-]- Equilibrium shifts to the left to oppose the change and maintain [OH-] conc- Conjugate acid reacts with more OH-
77
What does an acid buffer contain?
- Weak acid- Salt of the weak acid
78
What do you need to know to be able to calculate the pH of an acid buffer?
- [Acid]- [Salt]- Ka of the acid

AQA Physical Chemistry (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions