A Quinhydrone electrode in contact of ion is coupled with standard calomel electrode

CHEMISTRY · Single correct · CBSE · Chemistry · Electrochemistry · Electrochemistry

Problem

A Quinhydrone electrode in contact of

\text{H}^+

ion is coupled with standard calomel electrode. The

E^\circ

of both electrodes are given as :

\text{Pt} | \text{Q}, \text{QH}_2 | \text{H}^+ || 1\text{M KCl} | \text{Hg}_2\text{Cl}_2(s) | \text{Hg}(l) | \text{Pt}

\text{C}_6\text{H}_4(\text{CO})_2 + 2\text{H}^+ + 2e^- \longrightarrow \text{C}_6\text{H}_4(\text{OH})_2

E^0_{\text{Q}|\text{QH}_2|\text{H}^+|\text{Pt}} = +0.699 \text{ V}

\frac{1}{2} \text{Hg}_2\text{Cl}_2(s) + e^- \longrightarrow \text{Hg}(l) + \text{Cl}^-;

E^0_{\text{Cl}^-|\text{Hg}_2\text{Cl}_2|\text{Hg}} = +0.280 \text{ V}

If emf of cell so obtained is

-0.124

, then pH is : (1) 5 (2) 6 (3) 7 (4) 8