Redox Reactions And Electrochemistry Ques 221
Question: Aluminium displaces hydrogen from dilute HCl whereas silver does not. The e.m.f. of a cell prepared by combining $ Al/A{l^{3+}} $ and $ Ag/A{g^{+}} $ is 2.46 V. The reduction potential of silver electrode is $ +0.80\ V $ . The reduction potential of aluminium electrode is [KCET 2004]
Options:
A) $ +1.66\ V $
B) $ -3.26,V $
C) $ 3.26\ V $
D) $ -1.66\ V $
Show Answer
Answer:
Correct Answer: D
Solution:
Al displaces H from HCl but silver cannot it means Al is situated above the Ag in ECS, hence Al will acts as anode and Ag will act as cathode.
$ E_{cell}^{0}=E_{Cathode}^{0}-E_{Anode}^{0} $
$ =E_{A{g^{+}}/Ag}^{0}-E_{A{l^{3+}}/Al}^{0} $ $ 2.46=0.8-E_{A{l^{3+}}/Al}^{0} $ ; $ E_Al^{0}=0.8-2.46=-1.66\ V $ .
