acid base equilibria

Question 1

Brønsted acid

Answer 1

proton donor

Question 2

Brønsted base

Answer 2

proton acceptor

Question 3

Kw

Answer 3

Kw= [H+][OH-]

Question 4

Ka

Answer 4

Ka= [H+][A-]
——————
[HA]

Question 5

pH

Answer 5

pH=-log[H+]

Question 6

pKw

Answer 6

pKw=-logKw

Question 7

buffer solution

Answer 7

a solution which resists changes in pH on addition of small amounts of acid or alkali

Question 8

monobasic acid

Answer 8

donates 1 proton per molecule

Question 9

what are the units of Kw

Answer 9

mol2dm-6

Question 10

polybasic acid

Answer 10

one that dissolves in water to produce more than 1 hydrogen ion

Question 11

why will a specific indicator work

Answer 11

if the colour change interval of the indicator lies within the vertical region of the titration curve

Question 12

methyl orange

Answer 12

3.1-4.4 SASB SAWB

Question 13

methyl red

Answer 13

4.4-6.2
SASB SAWB

Question 14

phenolphthalein

Answer 14

8.3-10
SASB
WASB

Question 15

method for determining shape of titration curve

Answer 15

-place acid/base of known volume and conc in a conical flask
-record pH of solution using a pH meter or narrow range pH paper
-fill a burette with acid/base of standard conc
-add acid/base in 5cm3 portions from burette mixing with magnetic stirrer
-record pH after each addition
-add acid/base in 1cm3 portions as end point approaches
-continue to add two 5cm3 portions after the end point approaches
-ploy a graph pf pH against volume of solution added

Question 16

buffer equations

Answer 16

HCN<>CN- + H+ (buffer)
NaCN > Na + CN- (salt)
CN- + H+ > HCN (H+)
HCN + OH- > CN- + H2O (OH-)