2.1.5 redox

Question 1

Oxidation

Answer 1

Electron loss

Involves an increase in oxidation number

Zn > Zn2+ + 2e-

Question 2

Reduction

Answer 2

electron gain

Involves a decrease in oxidation number

Cl2 + 2e- > 2Cl-

Question 3

Uncombined numbers

Answer 3

Oxidation number of 0

Question 4

Hydrogen

Answer 4

+1 but -1 in NaH

Question 5

Oxygen

Answer 5

-2 except in peroxides (H2O2) where it is -1 and in compounds with fluorine

Question 6

Acid + metal

Answer 6

Salt + hydrogen

Produces effervesce as H2 gas is evolved and metal dissolves