Medium MCQ +4 / -1 PYQ · JEE Mains 2020

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 ]

  1. A Silver and gold in equal mass proportion
  2. B Silver and gold in proportion to their atomic weights
  3. C Only gold Correct answer
  4. D Only silver

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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