Question

$Z{n}_{\left(s\right)}+{C{u}_{\left(aq\right)}}^{2+}\to C{u}_{\left(s\right)}+{Z{n}_{\left(aq\right)}}^{2+}$

The EMF of the above reaction is 1.10 volt at 25${}^o$C. What is EMF of the cell when [Cu${}^{2+}$]=[Zn${}^{2+}$]=0.1M?

• A. 1.10 volt
• B. -1.10 volt
• C. 0.110 volt
• D. -0.110 volt

Answer 1

Answer: (A)

1.10 volt

$Z{n}_{\left(s\right)}+C{u}_{\left(aq\right)}^{2+}\to C{u}_{\left(s\right)}+Z{n}^{2+}\left(aq\right)$

Given $\left[C{u}^{2+}\right]=0.1,\left[Z{n}^{2+}\right]=0.1$

$n=2,E_{cell}^0=1.10$ volt

$E_{cell}=E_{cell}^0-\frac{0.059}{n}log\left[\frac{Z{n}^{2+}}{C{u}^{2+}}\right]$

$=1.10-\frac{0.059}{2}\text{log}\left[\frac{0.1}{0.1}\right]=1.10-\frac{0.059}{2}\text{log}1$

$=1.10-\frac{0.059}{2}\times 0=1.10V$

Hence, the correct option is $\text{A}$