redox

Question 1

reduction

Answer 1

gain of electrons
-decrease in oxidation number

Question 2

oxidation

Answer 2

loss of electrons
-increase in oxidation number

Question 3

chromium half equation

Answer 3

Cr2O7 2- + 14H+ 6e –> 2Cr 3+ + 7H2O

Question 4

manganese half equation

Answer 4

MnO4 + 8H+ + 5e –> Mn 2+ +4H2O

Question 5

hydrogen peroxide half equation

Answer 5

H2O2 –>O2 + 2H+ +2e

Question 6

iron half equation

Answer 6

Fe2+ –> Fe3+ + e

Question 7

iodine thiosulphate equation

Answer 7

2S2O3 2- + I2 –> 2I + S4O6 2-

Question 8

iodinethiosulphate reaction

Answer 8

starch s added making solution blue black then once all iodine is reduced to I- solution goes colourless
-end result