paper 3

Question 1

positive e circle thing

Answer 1

undergoes reduction (PR)

Question 2

negative e circle thing

Answer 2

undergoes oxidation (NO)

Question 3

positive electrode of a lithium cell

Answer 3

Li+ + CoO2 + e– → Li+[CoO2]

Question 4

negative electrode of a lithium cell

Answer 4

Li → Li+ + e–

Question 5

mg/ca2+ oh- observation

Answer 5

white ppt

Question 6

sr/ba2+ so42- observation

Answer 6

white ppt

Question 7

nh4+ test

Answer 7

dilute naoh + heat, damp red litmus blue

Question 8

oh- test

Answer 8

damp red litmus blue

Question 9

co32- test

Answer 9

dilute hcl, effervescence

Question 10

agcl solubility in ammonia

Answer 10

soluble in dilute or conc

Question 11

agbr solubility in ammonia

Answer 11

soluble in conc

Question 12

agi solubility in ammonia

Answer 12

insoluble

Question 13

naf h2so4 observations

Answer 13

steamy white fumes

Question 14

nacl h2so4 observations

Answer 14

steamy white fumes

Question 15

why do naf/cl not react further with h2so4

Answer 15

ions aren’t strong enough reducing agents to reduce s

Question 16

nabr h2so4 observations

Answer 16

brown fumes, colourless gas, steamy white fumes

Question 17

nai h2so4 observations

Answer 17

egg smell, black solid, steamy white fumes, yellow solid

Question 18

contact process

Answer 18

so2 + v2o5 > so3 + v2o4

v2o4 + 1/2o2 > v2o5

Question 19

formation of mn2+ from mno4- and c2o42-

Answer 19

2mno4- + 16h+ + 5c2o42- > 2mn2+ + 8h2o + 10co2

Question 20

mn2+ autocatalysis

Answer 20

4mn2+ + mno4- + 8h+ > 5mn3+ + 4h2o

2mn3+ + c2o42- > 2co2 + 2mn2+

Question 21

s2o82- and i-

Answer 21

s2o82- + 2fe2+ > 2so42- + 2fe3+

2i- + 2fe3+ > i2 + 2fe2+

Question 22

where does the more negative (oxidised) species go in the conventional representation?

Answer 22

left (unless hydrogen)