250 mL of a waste solution obtained from the
workshop of a goldsmith contains 0.1 M AgNO3
and 0.1 M AuCl. The solution was electrolyzed
at 2V by passing a current of 1A for 15
minutes. The metal/metals electrodeposited will
be
[ $E_{A{g^ + }/Ag}^0$ = 0.80 V, $E_{A{u^ + }/Au}^0$ = 1.69 V ]
Solution
Millimoles of Au<sup>+</sup> = 0.1 × 250 = 25
<br><br>Mole of Au<sup>+</sup> = ${{25} \over {1000}}$ = ${1 \over {40}}$
<br><br>Charge passed = I × t = 1 × 15 × 60 = 900 C
<br><br>moles of e<sup>–</sup> passed = ${{900} \over {96500}}$ = ${9 \over {965}}$
<br><br>Only gold will be deposited as quantity of
charge passed is less than the amount of Au<sup>+</sup>
present.
About this question
Subject: Chemistry · Chapter: Electrochemistry · Topic: Electrochemical Cells
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