Chapter 2

Question 1

properties of acids

Answer 1

dissolve in water to form solutions of pH<7
turn blue litmus indicator red
neutralise bases to salt + water
acids + carbonates form CO2 gas

Question 2

monoprotic acids

Answer 2

donate 1 mole protons for every mole acid

e.g. hydrochloric acid, nitric acid

Question 3

diprotic acid

Answer 3

donate 2 moles protons for every mole of acid

e.g. sulphuric

Question 4

properties of bases

Answer 4

associated with hydroxide ion (OH-)
when soluble base dissolves in water the solution is pH>7
turn red litmus indicator blue
denature proteins

Question 5

alkali

Answer 5

soluble base

Question 6

Bronsted-Lowry theory of acids and bases

Answer 6

acid-base neutralisation

H3O+ acts as Bronsted acid and donates proton to OH- (Bronsted base)

Question 7

Bronsted acid

Answer 7

proton donor

Question 8

Bronsted base

Answer 8

proton acceptor

Question 9

indicators

Answer 9

water-soluble dyes show colour change in diff pH solutions

Question 10

pH

Answer 10

negative logarithm to base 10 of aqueous H+ conc. (H3O+)

mol dm-3

Question 11

H conc. of monoprotic acid

Answer 11

conc. of acid itself

Question 12

strong acids

Answer 12

fully ionised in aqueous solution
1 mole of hydrogen chloride and water = 1 mole of aqueous H+ (weak means less than 1mole aq H)
pH of strong acid only depends on its conc.

Question 13

weak acids

Answer 13

partially ionised in aqueous solution
H3O+ conc. smaller than conc. of acid
equilibrium established between acid and ions
forms acid-base pair
forward reaction: acid donates proton to water (acts as base)
backward: acid donates proton to A- (base)
pH depends on conc. of acid and pKa

Question 14

pKa

Answer 14

-log10Ka

Question 15

strong bases

Answer 15

fully ionised so pH depends only on conc.

conc. OH = conc. base

Question 16

weak bases

Answer 16

partially ionised
OH conc. < base conc.
e.g. aqueous ammonia
equilibrium shifted left

Question 17

acid-base titrations

Answer 17

measure volumes of acid and base for neutralisation

plot volume against pH

Question 18

neutralisation

Answer 18

acid + base —> salt

when point of equivalence for titration reached (H3O+ = OH-)

Question 19

titration of strong acid with strong base

titration of strong acid and weak base

titration of weak acid with strong base

titration of weak acid with weak base

Answer 19

large pH change, small volumes, equivalence at pH7

base in excess, 1 acid drop before equivalence pH slightly >7, 1 acid drop after pH3

base in excess, end with acid in excess, large pH change near equivalence (11-7)

too gradual, conductivity low at start, improves as acid added, fully ionised salt

Question 20

acidic buffer

Answer 20

weak acid with corresponding salt

pH<7

Question 21

alkaline buffer

Answer 21

weak base with corresponding salt

pH>7