Chapter 20

Question 1

What is a monobasic acid?

Answer 1

One H+ ion can be replaced

Question 2

What is a dibasic acid?

Answer 2

Two H+ ions can be replaced

Question 3

What is a tribasic acid?

Answer 3

Three H+ ions can be replaced

Question 4

What is an ionic equation?

Answer 4

An equation that contains only the ions that are involved in the reaction, any spectator ions are removed.

Question 5

What are spectator ions?

Answer 5

Ions that undergo no change, and they stay aqueous throughout.

Question 6

What is a Bronsted-Lowry acid?

Answer 6

A proton donor

Question 7

What is a Bronsted-Lowry base?

Answer 7

A proton acceptor

Question 8

What does an acid/base reaction involve?

Answer 8

A transfer of protons

Question 9

What is a conjugate acid-base pair?

Answer 9

Contains two species that can be interconverted by transfer of a proton.

Question 10

What is a strong acid?

Answer 10

An acid that completely dissociates in a solution

Question 11

What is a weak acid?

Answer 11

An acid that partially dissociates in aqueous solution

Question 12

What is the pH?

Answer 12

A measure of the concentration of H+ ions in a solution

Question 13

What is the equation for calculating the pH?

Answer 13

pH = -log[H+].

Question 14

What is the equation for calculating H+ from the pH?

Answer 14

[H⁺] = 10 ^−pH

Question 15

What is the equation for H+ ions from a strong monobasic acid?

Answer 15

[HA]=[H+]

Question 16

How do you calculate the pH after a dilution?

Answer 16

New concentration = original concentration x (Volume of reagent/Total volume)

Question 17

What is the acid dissociation constant?

Answer 17

The Kc expression for a weak acid, applied to the dissociation equation

Question 18

What is the equation for Ka?

Answer 18

[H+][A-]/[HA]

Question 19

How do you calculate PKa?

Answer 19

PKa = -log₁₀ (Ka)

Question 20

What does the size of Ka tell us?

Answer 20

The larger the value for Ka, the stronger the weak acid
Ka is temperature dependent

Question 21

What is the calculation for Ka from Pka?

Answer 21

Ka = 10^ (-pKa)

Question 22

What does the value of PKa tell us?

Answer 22

The smaller the pKa, the stronger the weak acid

Question 23

What approximations can be used to simplify the Ka expression?

Answer 23

[H+]=[A-]
[HA] start = [HA] end

Question 24

What is the equation for Ka with the approximations?

Answer 24

Ka = [H+]^2/[HA]start

Question 25

What are the limitations to the approximation that [H+] = [A-] ?

Answer 25

The approximation will break down for very weak acids or very dilute acids

Question 26

What are the limitations to the approximation [HA]start = [HA]end ?

Answer 26

The approximation is not justified for stronger weak acids

Question 27

How do you determine Ka experimentally?

Answer 27

Prepare a standard solution of the weak acid of known concentration Measure the pH of the standard solution

Question 28

What is the equation for the ionisation of water?

Answer 28

Kw = [H+][OH-]

Question 29

What does Kw stand for?

Answer 29

The ionic product of water

Question 30

How do you calculate the pH of pure water?

Answer 30

water is neutral [H+] = [OH-] Kw is temperature dependent

Question 31

When is a solution neutral?

Answer 31

When [H+] = [OH-]

Question 32

When is a solution acidic?

Answer 32

When [H+] > [OH-]

Question 33

When is a solution alkali?

Answer 33

When [H+] < [OH-]

Question 34

How can you calculate the pH of a strong base?

Answer 34

The concentration of the base The Kw value