9. Acid base eqm

Question 1

definition of strong acid

Answer 1

completely dissociates in aq solution

Question 2

definition of weak acid

Answer 2

partial dissociation in aq solution

Question 3

the stronger the acid, the higher the conc. of of acid. T/F?

Answer 3

false. strength of acid not the same as concentration

Question 4

definition of bases

Answer 4

compounds that neutralise acids

Question 5

all bases are soluble in water. T/F

Answer 5

false. only alkalis are soluble in water

Question 6

what is the Arrhenius theory of acids and base?

Answer 6

acid contain hydrogen and are H+ donors while bases contain -OH and releases OH ions in aq solution

Question 7

limitations of Arrhenius theory of acid and bases [3]

Answer 7

1. restrict acid base rxns to those that occur in aq solution
2. does not account for basic properties of ammonia and other basic compounds that dont have -OH grp
3. theory focuses on H+ ions but no such ion exist in aq solution
   *H+ has high charge density and forms dative covalent bond w H2O to form H3O+

Question 8

describe the Bronsted Lowry theory of acids and bases

Answer 8

Bronsted Lowry acid is a proton donor (eg. H+), Bronsted Lowry base is a proton acceptor.

hence, acid is only and acid in presence of a base and vice versa.

Question 9

is water an acid or base?

Answer 9

both. water is amphoteric and can donate/accept electrons

Question 10

describe what are Lewis acid and bases.

Answer 10

Lewis acid: any species that can accept a pair of electrons from a base to form a dative covalent bond
Lewis base: ‘’ donate a pair of electrons to an acid to form a dative covalent bond

Question 11

when talking about acid-base phenomena in aq solutions, which theory do we use? why?

Answer 11

Bronsted-lowry theory

focuses on proton transfer

Question 12

formula of pH

Answer 12

pH=-lg[H+] or
pH= 14-pOH

Question 13

formula of pOH

Answer 13

pOH= -lg[OH-]
or
14-pH

Question 14

methods to measure pH [2]

Answer 14

1. universal indicator
2. pH meter

Question 15

what is the ionic pdt of water at 25deg?

Answer 15

at 25deg, pKw= pH+pOH = 14

Question 16

does ionic product of water (Kw) increase/decrease with increasing temperature?

Answer 16

increase. self-ionisation of water is endothermic process. According to LCP, heating promotes more dissociation of water to H+ and OH-

Question 17

acids only have 1 acid dissociation constant. T/F?

Answer 17

false for polyprotic acids eg. H2SO4, H2CO2 –> no. of Ka depends on number of