In acidic solution the half-reaction below is partially written

CHEMISTRY · Single correct · A Level · Chemistry · Oxidation, reduction and redox reactions · Oxidation, reduction and redox reactions

Problem

In acidic solution the half-reaction below is partially written.

\text{Cr}_2\text{O}_7^{2-} + 14\,\text{H}^+ + \_\_\_\,e^- \rightarrow 2\,\text{Cr}^{3+} + 7\,\text{H}_2\text{O}

What integer coefficient of electrons balances the charge in this half-reaction? (a) 7 (b) 3 (c) 6 (d) 8