Question

Given the reaction: __hg2+ + __ag0 → __hg0 + __ag1+when the equation is completely balanced using the smallest whole-number coefficients, the coefficient of hg will be

Answer 1

Answer is: the coefficient of Hg will be 1.

Balanced chemical reaction: Hg²⁺ + 2Ag⁰ → Hg⁰ + 2Ag⁺.
Oxidation half reaction: Ag⁰ → Ag⁺ + e⁻/×2; 2Ag⁰ → 2Ag⁺ + 2e⁻
Reduction half reaction: Hg²⁺ + 2e⁻ → Hg⁰.
Mercury cation gain two electrons and become mercury metal with neutral charge (reduction), silver lost electrons and become silver cation (oxidation).