Acids and Bases

Question 1

Bronsted-Lowry acid?

Answer 1

proton donor

Question 1

Bronsted-Lowry base?

Answer 1

proton acceptor

Question 2

conjugate acid?

Answer 2

species formed when a proton is added to a base

Question 3

conjugate base?

Answer 3

species formed when a proton is removed from an acid

Question 4

Define buffer solution

Answer 4

solution that resists changes to pH when small amounts of an acid or a base is added

Question 5

Bronsted-Lowry acid-base reaction

Answer 5

reaction involving the transfer of a proton

Question 6

difference between monoprotic acid and diprotic acid

Answer 6

Monoprotic acid = acid that releases one H+ ion per molecule
e.g. HCl (hydrochloric acid), HNO3 (nitric acid), CH3COOH (ethanoic acid)

Diprotic acid = acid that releases two H+ ions per molecule e.g. H2SO4 (sulfuric acid), H2C2O4 (ethanedioic acid)

Question 7

definition of pH?

Rearrange it

How many decimal places should pH be given to?

Answer 7

pH = – log [H+]

[H+] = 10^-pH

2 d.p.

Question 8

[H2SO4] when pH = 1.30

Answer 8

[H+] = 10^-1.30 = 0.0501
[H2SO4] = 0.0501/2 = 0.0251

Question 8

ionic product of water expression?

value of kW

Answer 8

[H+][OH-]

1.00 x 10^-14

Question 9

Work out pH of strong acids

Work out pH of weak acids

Work out pH of acid buffers

Answer 9

Strong acids:
-use pH equation

Weak acids:
Use Ka, assume that [H+] = [OH-]

Acidic buffers:
-the above does not apply

Question 10

Why does Kw increase when temp increases?

Answer 10

ionisation of water is an endothermic pocess
water only very slightly dissociates

Question 11

Why does the expression for Kw not include concentration of water? (2 marks)

Answer 11

M1: [H2O] is very high
OR
very few H+ and OH- ions
OR
Only/very slightly dissociates

M2: [H2O] is relatively constant