24.5 redox and qualitative analysis

Question 1

colour of MnO4-

Answer 1

purple

Question 2

colour change in reaction of Fe2+ and MnO4-

Answer 2

purple to colourless

Question 3

how is Fe2+ oxidised to Fe3+

Answer 3

react with MnO4- ions

Question 4

reaction of Fe2+ and MnO4 -

Answer 4

Question 5

colour of Mn2+

Answer 5

colourless

Question 6

colour of Fe3+

Answer 6

orange-brown

Question 7

colour of Fe2+

Answer 7

pale green

Question 8

how is Fe3+ reduced to Fe2+

Answer 8

react with I-

Question 9

reaction of Fe3+ and I-

Answer 9

Question 10

colour change in reaction of Fe3+ and I-

Answer 10

orange-brown to brown

Question 11

colour of Cr2O7 2-

Answer 11

orange

Question 12

colour of Cr3+

Answer 12

green

Question 13

colour of Cr2+

Answer 13

pale blue

Question 14

how is Cr2O7 2- reduced to Cr3+

Answer 14

react with Zn

Question 15

reaction of Cr2O7 2- and Zn

Answer 15

Question 16

colour change in reaction of Cr2O7 2- and Zn

Answer 16

orange to green

Question 17

how is Cr3+ reduced to Cr2+

Answer 17

add excess zinc

Question 18

reaction of Cr3+ and excess zinc

Answer 18

Question 19

colour change in reaction of Cr3+ and excess Zn

Answer 19

green to pale blue

Question 20

how is Cr3+ oxidised to CrO4 2-?

Answer 20

react with H2O2

Question 21

Cr3+ colour

Answer 21

green

Question 22

how is Cu2+ reduced to Cu+

Answer 22

react with I-

Question 23

what is formed in this reaction?

Answer 23

CuI precipitate
brown solution

Question 24

colour of Cu2+

Answer 24

pale blue

Question 25

colour of CuI

Answer 25

white precipitate

Question 26

colour of I2

Answer 26

brown solution

Question 27

reaction of Cu2+ and I-

Answer 27

Question 28

what is Cu+ able to do?

Answer 28

as it is very unstable it is able to disproportionate into Cu and Cu2+ ions so it is both oxidised and reduced

Question 29

reaction when Cu2O reacts with H2SO4

Answer 29