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Chemistry · REDOX REACTIONS
हिन्दीA piece of zinc metal weighing \( 6.54\text{ g} \) is placed in an aqueous solution containing \( 0.050\text{ mol} \) of \( \text{Cu}^{2+} \) ions: \( \text{Zn}(\text{s}) + \text{Cu}^{2+}(\text{aq}) \rightarrow \text{Zn}^{2+}(\text{aq}) + \text{Cu}(\text{s}) \). How many moles of electrons are transferred during the reaction, and which reactant remains in excess? (Atomic mass of \( \text{Zn} = 65.4\text{ g mol}^{-1} \))
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Correct answer · Option B
\( 0.10\text{ mol } e^- \), \( \text{Zn} \) in excess
Explanation
Initial moles of \( \text{Zn} = \frac{6.54}{65.4} = 0.10\text{ mol} \). \( \text{Cu}^{2+} \) is the limiting reagent (\( 0.050\text{ mol} \)). Each \( \text{Cu}^{2+} \) requires \( 2e^- \), so moles of electrons transferred \( = 0.050 \times 2 = 0.10\text{ mol} \), leaving \( 0.050\text{ mol} \) of \( \text{Zn} \) in excess.
