What is the oxidizing agent in the following reaction?

Pyruvate + NADH + H + → Lactate + NAD+

a. oxygen

b. NADH

c. lactate

d. pyruvate

The answer is d. pyruvate

Explanation:

An oxidizing agent is the substance that gains electrons in a chemical reaction. At the end of the reaction it is reduced and its oxidation state increased.

A reducing agent is the substance that loses electrons in a chemical reaction. At the end of the reaction it is oxidized and its oxidation state decreased.

Pyruvate gains one electron, it is reduced from pyruvate to lactate; thus, pyruvate is the oxidizing agent.

NADH loses one electron, it is oxidized from NADH to NAD; thus, NADH is the reducing agent