21.1 - 21.6 Acids, bases and buffers

Question 1

Give the Bronsted-Lowry definition of an acid

Answer 1

A proton/H+ donor

Question 2

Give the Bronsted-Lowry definition of a base

Answer 2

A proton/H+ acceptor

Question 3

Give the Bronsted-Lowry definition of an acid-base reaction

Answer 3

A reaction involving proton transfer

Question 4

Define amphoteric

Answer 4

A substance that acts as an acid or a base i.e water

Question 5

Give the Lewis definition of an acid

Answer 5

An electron pair acceptor

Question 6

Give the Lewis definition of a base

Answer 6

An electron pair donor

Question 7

Define a strong acid

Answer 7

An acid that fully dissociates in water

Question 8

What is the equation for calculating pH?

Answer 8

-log [H+]

Question 9

What is the equation for calculating [H+]?

Answer 9

[H+] = 10^-pH

Question 10

How do you calculate the dilution of a strong acid?

Answer 10

C1 x V1 = C2 x V2

Question 11

Define Kw

Answer 11

Kw = [H+] x [OH-]

Question 12

Why is pure water always neutral?

Answer 12

Because [H+] = [OH-]

Question 13

How do you calculate the pH of strong alkalis?

Answer 13

1. Calculate [OH-]
2. Use Kw to calculate [H+]
3. Use pH = -log[H+]

Question 14

How do you use Kw to calculate [H+]?

Answer 14

[H+] = Kw/[OH-]

Question 15

How do you calculate the pH of a mixture of a strong acid and a strong base?

Answer 15

1. moles H+
2. moles OH-
3. XS moles of H+ or OH-
4. [H+] or [OH-]
5. pH

Question 16

How do you calculate the pH of a weak acid?

Answer 16

[H+]^2 = Ka x [Ha]

Question 17

How do you calculate the pH of a mixture of a weak acid and a strong base?

Answer 17

1. Calculate moles HA
2. Calculate moles OH-
3. Calculate moles XS HA or OH-

XS HA:
- Moles HA left
- Moles A- formed
- [HA] and [A-]
- [H+] = Ka x [HA] / [A-]
- pH

XS OH-:
- [OH-]
- [H+] = Kw/[OH-]
- pH

Question 18

List the strong acids

Answer 18

HCl
HNO3
H2SO4

Question 19

List the weak acids

Answer 19

Carboxylic acids

Question 20

List the strong bases

Answer 20

NaOH
KOH
Ba(OH)2

Question 21

List the weak bases

Answer 21

NH3

Question 22

Give the Ka equation

Answer 22

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

If a weak acid in solution with nothing else:
Ka = [H+]^2 / [HA]

Question 23

Describe how to convert between Ka and pKa

Answer 23

pKa = -log(Ka)
Ka = 10^-pKa

Question 24

Describe the relation between Ka and pKa and pH

Answer 24

Ka up = pH down
pKa down = pH down