JEE MAIN - Chemistry (2020 - 4th September Evening Slot - No. 16)
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 ]
[ $$E_{A{g^ + }/Ag}^0$$ = 0.80 V, $$E_{A{u^ + }/Au}^0$$ = 1.69 V ]
Silver and gold in equal mass proportion
Silver and gold in proportion to their atomic
weights
Only gold
Only silver
Explanation
Millimoles of Au+ = 0.1 × 250 = 25
Mole of Au+ = $${{25} \over {1000}}$$ = $${1 \over {40}}$$
Charge passed = I × t = 1 × 15 × 60 = 900 C
moles of e– passed = $${{900} \over {96500}}$$ = $${9 \over {965}}$$
Only gold will be deposited as quantity of charge passed is less than the amount of Au+ present.
Mole of Au+ = $${{25} \over {1000}}$$ = $${1 \over {40}}$$
Charge passed = I × t = 1 × 15 × 60 = 900 C
moles of e– passed = $${{900} \over {96500}}$$ = $${9 \over {965}}$$
Only gold will be deposited as quantity of charge passed is less than the amount of Au+ present.
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