Question

Sodium sulfate reacts with carbon to produce the products sodium sulfide and carbon monoxide. Identify the reducing agent in the following reaction.
Na2SO4 + 4C yields Na2S + 4CO

Na2SO4
C
Na2S
CO

Answer 1

@james238867

Answer 2

A reducing agent is an element or compound that donates electrons to another element.
To solve this question, write the oxidation numbers of each element.
Reactants
Na is +1
S is +6
O is -2
C is 0

Products
Na is+2
S is -2
C is +2
O is -2

Therefore, Na donated an electron (is oxidized) and S gained electrons (is reduced).
However the term reducing agent refers to the element/compound causing the reduction. In this instance, it is Na2SO4.

Answer 3

The key to this question is knowing oxidation numbers, and keeping oxidation, reduction, oxidizing agent, and reducing agent clear in your head.
...I'm not sure if that's completely clear in mine.
However, if you intend on taking chemistry for the AP, oxidizing agent and reducing agent are no longer testable terms.