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Estimate the mass of copper metal produced during the passage of 5 A current through `CuSO_(4)` solution for 100 minutes. The molar mass of Cu is 63.5 g `mol^(-1)` |
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Answer» Correct Answer - Mass of Cu metal formed `=9 .87 g` Given : Electric current = I = A Time = t = 100 min = 100 `xx 60 s = 6000 s ` Molar mass of Cu = Atomic mass of Cu = 63.5 g `mol^(-1)` Mass of cu deposited = ? Reduction half reaction at cathode . `Cu_((ag))^(++) + 2e^(-) to Cu_((s))` Quantity of electricity `= Q= I xx t = 5 xx 6000 = 3000 C` Number of moles of electrons passed `= (Q)/(F ) ` `= (3000)/(96500) "mol"` ` C "mol"^(-1)` `= 0.3109 "mol"` From the half reduction reaction 1 mol of Cu is formed by the passage of 2 moles of electrons. Molar ratio of Cu `= ("Molar of Cu formed " )/("Number of moles of electron " ) ` `= (1 " mol " ) /(2 " mol " ) =0.5 ` Number of moles of Cu formed = Number of moles of electrons passed `xx ` Mole ratio `= 0.3109 xx 0.5 = 0.1554` mol Mass of Cu formed = Moles of Cu formed `xx` Molar Mass of Cu `= 0.1554 xx 63.5 = 9.87 g` |
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