Variable oxidation states Redox

Question 1

WHAT COLOUR IS :

MnO 4- (aq)

Answer 1

PURPLE

Question 2

WHAT COLOUR IS :

Mn 2+ (aq)

Answer 2

PALE PINK / COLOURLESS

Question 3

WHAT COLOUR IS :

Fe 3+

Answer 3

BROWN

Question 4

WHAT COLOUR IS :

Fe 2+

Answer 4

GREEN

Question 5

WHAT COLOUR IS :

Cr2O7 2-

Answer 5

ORANGE

Question 6

WHAT COLOUR IS :

Cr 3+

Answer 6

GREEN

Question 7

WHAT COLOUR IS :

Cr(OH)6 3-

Answer 7

DARK GREEN

Question 8

WHAT COLOUR IS :

CrO4 2-

Answer 8

YELLOW

Question 9

WHAT COLOUR IS :

Cu+ (REDUCTION CU 2+ TO CU +)

Answer 9

WHITE PRECIPITATE (CUI)
BROWN SOLUTION (I2)

2Cu 2+ (aq) + 4I - (aq) –> I2(aq) + 2CuI (s)

Question 10

WHAT IS THE FULL EQUATION FOR THE DISPROPORTIONATION OF CU + IONS

Answer 10

Cu2O + H2SO4 –> CuSO4 + Cu + H2O

Question 11

How is Fe 3+ reduced to Fe 2+

Answer 11

2Fe 3+ (aq) + 2I- (aq) –> I2(aq) + 2Fe 2+ (aq)

Question 12

How is Cr 3+ made by reduction

Answer 12

by reduction of Cr2O7 2- (orange) by the strong reducing agent zinc in (HCl) acid solution

Question 13

what happens when Cr 3+ is reacted with an excess of Zn

Answer 13

It is reduced further to Cr 2+

Question 14

WHAT COLOUR IS:

Cr 2+

Answer 14

PALE BLUE

Question 15

How is Cr 3+ reduced to CrO4 2-

Answer 15

Hot alkaline Hydrogen Peroxide
H2O2

Question 16

How is Cu 2+ reduced to Cu +

Answer 16

reaction with excess Iodide ions