Question

What element is reduced in the following reaction?

Pb + SO42- + AuCl4- yields PbSO4 + Au + Cl-

A) Pb

B) Au

C) S

D) O

Answer 1

the oxidation states of the elements before and after the reaction is;
Pb oxidation state changes from 0 to +2
SO₄²⁻ ion there's no change in the oxidation state during the reaction
Au oxidation state changes from +3 to 0
reduction reactions are when there's a decrease in the oxidation state of the species
oxidation reactions are when theres an increase in the oxidation state of the species
the element where there's a decrease in oxidation state is Au.
Therefore Au gets reduced.
answer is B) Au