c
\(\begin{gathered}
  Fe\,\, + \,\,2HCl\,\, \to \,\,FeC{l_2}\,\, + \,\,{H_2} \hfill \\
  \,\,\,\,\,\,\,\,\,\,\frac{{50}}{{56}}\,mol\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{{50}}{{56}}\,mol \hfill \\ 
\end{gathered} \)

\(25\,^oC\) ઉદ્ભવતું \(H_2\) નુ કદ \(V\,\, = \,\,\frac{{nRT}}{P}\,\, = \,\,\frac{{50}}{{56}}\,\, \times \,\,\frac{{0.0821\,\, \times \,\,298}}{1}\,\, = \,\,21.842\,\,lit.\)

તેથી \({\text{W}}{\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {\text{  -  P }}\Delta {\mkern 1mu} {\text{V}}{\mkern 1mu} {\mkern 1mu} \)

\( = {\mkern 1mu} {\mkern 1mu} {\text{  -  P(}}{{\text{V}}_{\text{f}}}{\mkern 1mu} {\text{  -  }}{\mkern 1mu} {\mkern 1mu} {{\text{V}}_{\text{i}}}{\text{)}}{\mkern 1mu} {\mkern 1mu} \)

\( = {\mkern 1mu} {\mkern 1mu} {\text{  -  1}}{\mkern 1mu} {\mkern 1mu}  \times {\mkern 1mu} {\mkern 1mu} {\text{(21}}{\text{.842}}{\mkern 1mu} {\text{  -  }}{\mkern 1mu} {\mkern 1mu} {\text{0)}}{\mkern 1mu} \)

\( = {\mkern 1mu} {\mkern 1mu} {\text{  -  1}}{\mkern 1mu} {\mkern 1mu}  \times {\mkern 1mu} {\mkern 1mu} {\text{21}}{\text{.84}}{\mkern 1mu} {\text{L}}{\mkern 1mu} {\text{  -   atm}}\)

\(\therefore {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\text{W}}{\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {\text{  -  }}{\mkern 1mu} {\text{2212}}{\text{.39}}{\mkern 1mu} \,{\text{J}}\)