Answer to Question #347662 in General Chemistry for gem

Question

3. Use the changes in oxidation numbers to identify which atoms are oxidized and which are reduced in each reaction:

a. 2H2 (g) + O2(g) →2H2O(l)

b. 2KNO3(s)→2KNO2(s)+ O2(g)

c. NH4NO2(s) →N2(g) + 2H2O(g)

Answer 1

Solution:

(a): 2H₂(g) + O₂(g) → 2H₂O(l)

Oxidation half-reaction:

H₂⁰ − 2e⁻ → 2H⁺

Reduction half-reaction:

O₂⁰ + 4e⁻ → 2O⁻²

Therefore,

Hydrogen (H) atoms are oxidized

Oxygen (O) atoms are reduced

(b): 2KNO₃(s) → 2KNO₂(s) + O₂(g)

Oxidation half-reaction:

2O⁻² − 4e⁻ → O₂⁰

Reduction half-reaction:

N⁺⁵ + 2e⁻ → N⁺³

Therefore,

Oxygen (O) atoms are oxidized

Nitrogen (N) atoms are reduced

(c): NH₄NO₂(s) → N₂(g) + 2H₂O(g)

Oxidation half-reaction:

2N⁻³ − 6e⁻ → N₂⁰

Reduction half-reaction:

2N⁺³ + 6e⁻ → N₂⁰

Therefore,

Nitrogen (N) atoms in NH₄⁺ are oxidized

Nitrogen (N) atoms in NO₂⁻ are reduced