MCAT General Chemistry Review - Alexander Stone Macnow, MD 2019-2020

Oxidation–Reduction Reactions
Answers to Concept Checks

· 11.1

1.

Reaction

Oxidation Numbers

Oxidizing Agent

Reducing Agent

2 KI + H2 → 2 K + 2 HI

Image

K+ (charge goes from +1 to 0)

H2 (charge goes from 0 to +1)

Al + BPO4 → B + AlPO4

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B3+ (charge goes from +3 to 0)

Al (charge goes from 0 to +3)

2. Oxidation: Zn → Zn2+ + 2 e

Reduction: Cu2+ + 2 e → Cu

3. Image

· 11.2

1. Cu+ + Cl → CuCl

3 Mg + 2 Al3+ → 3 Mg2+ + 2 Al (don’t forget to balance the reaction!)

2. In the first reaction, chlorine undergoes disproportionation to have a —1 oxidation state in NaCl and a +5 oxidation state in NaClO3.

In the second reaction, sulfur undergoes disproportionation to have a 0 oxidation state in elemental sulfur and +4 oxidation state in SO2.

3. Image

Note that question 3 also included the extraneous value 10.0 g, which is not needed to calculate the mass of lead produced.