Question

Consider the chemical reaction below.

Zn(s) + 2H+(aq) mc001-1.jpg Zn2+(aq) + H2(g)

Which half reaction correctly represents reduction for this equation?
Zn(s) mc001-2.jpg Zn2+(aq) + 2e–
2H+(aq) + 2e– mc001-3.jpg H2(g)
Zn(s) mc001-4.jpg Zn2+(aq) + e–
2H+(aq) + e– mc001-5.jpg H2(g)

Answer 1

2H+(aq) + 2e– → H2(g)

Explanation: Reduction is gain of electrons. The hydrogen ions gain two electrons to form H2, while zinc is oxidized (Zn → Zn2+ + 2e–).