Chromium metal can be plated out from an acidic solution containing `CrO_3` , according to the following equation `CrO_3(aq)+6 H^+(aq)+6 e^-` → `Cr(s)+3 H_2 O,` Cal culate (i) how many grams of chromium will be plated out by `24000 C` and (ii) how long will it take to plate out `1.5 g` of chromium by using `12.5 A` current? (atomic mass of `Cr=52` )

Explanation

Ans:
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i) CrO_3+6 H^*+6 e Cr+3 H_2 C
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Hence 6 moles of e deposit `52 ~g` Cr
i.e. `6 ~F` deposit `52 ~g Cr` `6 xx 96500 C` deposit `52 ~g` Cr.
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therefore 24000 C deposit =52 xx 24000/6 xx 96500=2.155 ~g Cr
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