Redox Reactions And Electrochemistry Ques 125

Question: A solution containing one mole per litre of each Cu(NO3)2,AgNO3,Hg2(NO3)2 and Mg(NO3)2, is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts (reduction potentials) are Ag/Ag+=+0.80,2Hg/Hg22+=+0.79,Cu/Cu2+=+0.34, Mg/Mg2+=2.37 with increasing voltage, the sequence of deposition of metals on the cathode will be [IIT 1984; AMU 1999; Kerala PMT 2004]

Options:

A) Ag,Hg,Cu,Mg

B) Mg,Cu,Hg,Ag

C) Ag,Hg,Cu

D) Cu,Hg,Ag

Show Answer

Answer:

Correct Answer: C

Solution:

A cation having highest reduction potential will be reduced first and so on. However, Mg2+ in aqueous solution will not be reduced (EMg2+/Mg0<EH2O/12H2+OH) . Instead water would be reduced in preference.



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