285409 For\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \mathrm{E}^{\circ}=\) \(1.33 \mathrm{~V} \mathrm{At}\left[\mathrm{Cr}_2 \mathrm{O}_7^{2-}\right]=4.5\) millimole, \(\left[\mathrm{Cr}^{3+}\right]=15\) millimole, E is 1.067 V . The pH of the solution is nearly equal to

285410 Impure copper containing\(\mathrm{Fe}, \mathrm{Au}, \mathrm{Ag}\) as impurities is electrolytically refined. A current of 140 A for 482.5 s decreased the mass of the anode by 22.26 g and increased the mass of cathode by 22.011 g . Percentage of iron in impure copper is
(Given : molar mass \(\mathrm{Fe}=55.5 \mathrm{~g} \mathrm{~mol}^{-1}\), molar mass \(\mathrm{Cu}=63.54 \mathrm{~g} \mathrm{~mol}^{-1}\) )

285411 For hydrogen - oxygen fuel cell at one atm and 298 K
\(\mathrm{H}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{l}) ; \Delta \mathrm{G}^{\circ}=-240 \mathrm{~kJ}\)
\(\mathrm{E}^{\circ}\) for the cell is approximately,

(Given : \(F=96,500 \mathrm{C}\) )

285409 For\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \mathrm{E}^{\circ}=\) \(1.33 \mathrm{~V} \mathrm{At}\left[\mathrm{Cr}_2 \mathrm{O}_7^{2-}\right]=4.5\) millimole, \(\left[\mathrm{Cr}^{3+}\right]=15\) millimole, E is 1.067 V . The pH of the solution is nearly equal to

285410 Impure copper containing\(\mathrm{Fe}, \mathrm{Au}, \mathrm{Ag}\) as impurities is electrolytically refined. A current of 140 A for 482.5 s decreased the mass of the anode by 22.26 g and increased the mass of cathode by 22.011 g . Percentage of iron in impure copper is
(Given : molar mass \(\mathrm{Fe}=55.5 \mathrm{~g} \mathrm{~mol}^{-1}\), molar mass \(\mathrm{Cu}=63.54 \mathrm{~g} \mathrm{~mol}^{-1}\) )

285411 For hydrogen - oxygen fuel cell at one atm and 298 K
\(\mathrm{H}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{l}) ; \Delta \mathrm{G}^{\circ}=-240 \mathrm{~kJ}\)
\(\mathrm{E}^{\circ}\) for the cell is approximately,

(Given : \(F=96,500 \mathrm{C}\) )

285409 For\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \mathrm{E}^{\circ}=\) \(1.33 \mathrm{~V} \mathrm{At}\left[\mathrm{Cr}_2 \mathrm{O}_7^{2-}\right]=4.5\) millimole, \(\left[\mathrm{Cr}^{3+}\right]=15\) millimole, E is 1.067 V . The pH of the solution is nearly equal to

285410 Impure copper containing\(\mathrm{Fe}, \mathrm{Au}, \mathrm{Ag}\) as impurities is electrolytically refined. A current of 140 A for 482.5 s decreased the mass of the anode by 22.26 g and increased the mass of cathode by 22.011 g . Percentage of iron in impure copper is
(Given : molar mass \(\mathrm{Fe}=55.5 \mathrm{~g} \mathrm{~mol}^{-1}\), molar mass \(\mathrm{Cu}=63.54 \mathrm{~g} \mathrm{~mol}^{-1}\) )

285411 For hydrogen - oxygen fuel cell at one atm and 298 K
\(\mathrm{H}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{l}) ; \Delta \mathrm{G}^{\circ}=-240 \mathrm{~kJ}\)
\(\mathrm{E}^{\circ}\) for the cell is approximately,

(Given : \(F=96,500 \mathrm{C}\) )