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InterviewSolution
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The standard electrode potential corresponding to the reaction Au3+(aq) + 3e- → Au(s) is 1.5 V. Predict if gold can be dissolved in 1M HCl solution and on passing hydrogen gas through gold salt solution, metallic gold will be precipitated or not. |
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Answer» Consider the half reaction, 2H+(aq) + 2e– → H2(g); E° = 0.0V Au3+(aq) + 3e– → Au(s); E° = 1.50V Since E° (1.50V) for (Au3+/Au) is higher than that H+/-\(\frac{1}{2}\)H2 (0.0V), therefore, Au3+ can be more easily reduced than H+ ions Au3+ can be reduced to Au metal by H2 but H+ cannot oxidize metallic gold to Au3+ ions. In other words, metallic gold does not dissolve in 1M HCl instead H2 gas can reduce gold salt to metallic gold. |
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