An electrochemical cell is set up as: $\mathrm{Pt} ; \mathrm{H}_{2}(1 \mathrm{~atm})\left|\mathrm{HCl}(0.1…

An electrochemical cell is set up as:
$\mathrm{Pt} ; \mathrm{H}_{2}(1 \mathrm{~atm})\left|\mathrm{HCl}(0.1 \mathrm{M}) \| \mathrm{CH}_{3} \mathrm{COOH}(0.1 \mathrm{M})ight| \mathrm{H}_{2}$ (1atm); Pt.
The e.m.fof this cell will not be zero, because
  1. the temperature is constant
  2. e.m.f depends on molarities of acids used
  3. acids used in two compartments are different
  4. $\mathrm{pH}$ of $0.1 \mathrm{M} \mathrm{HCl}$ and $0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ is not same

Solution

For a concentration cell having different concentrations of ions. $E=-\frac{0.0591}{\mathrm{n}} \log \frac{\mathrm{c}_{1}}{\mathrm{c}_{2}}$
If all the concentrations are identical then obviously the cell voltage is zero. But as the $\mathrm{pH}$ of $0.1 \mathrm{M} \mathrm{HCl}$ (strong acid) and $\mathrm{pH}$ of $0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ is (weak acid) not same, therefore the cell voltage is not zero. *

Asked in: JEE-TOPICTESTS-CHEMISTRY

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