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Question : 24
Total: 26
(a) Calculate E ° cell for the following reaction at 298K :
2 Al ( s ) + 3 Cu 2 + ( 0.01 M ) → 2 Al 3 + ( 0.01 M ) + 3 Cu ( s )
Given : E ∘ cell = 1.98 V
(b) Using theE ∘ values of A and B , predict which is better for coating the surface of iron [E ∘ ( Fe 2 + ∕ Fe ) = − 0.44 V ] to prevent corrosion and why ?
Given :E ° ( A 2 + ∕ A ) = − 2.37 V : E ° ( B 2 + ∕ B ) = − 0.14 V
OR
(a) The conductivity of0.001 mol L − 1 solution of CH 3 COOH is 3.905 × 10 − 5 S cm − 1 . Calculate its molar conductivity and degree of dissociation ( α ) .
Givenλ 0 ( H + ) = 349.6 S cm mol − 1 and λ 0 ( CH 3 COO − ) = 40.9 S cm 2 mol − 1
(b) Define electrochemical cell. What happens if external potential applied becomes greater thanE ∘ cell of electrochemical cell ?
(b) Using the
Given :
OR
(a) The conductivity of
Given
(b) Define electrochemical cell. What happens if external potential applied becomes greater than
Solution:
(a) E cell = E 0 cell −
log
E 0 cell = E cell +
log
E 0 cell = 1.98 V +
log
1
E 0 cell = 1.98 V +
log 10 2
E 0 cell = 1.98 V +
× 2 × log 10 [ ∵ log 10 = 1 ]
E 0 cell = 1.98 V +
× 2
E 0 cell = 1.98 V + 0.0197 V
E 0 cell = 1.9997 V
(b)A , because its E 0 value is more negative
OR
(a)Λ m = κ × 1000 ∕ C
=
= 39.05 cm 2 ∕ mol
α =
=
= 0.1
CH 3 COOH → CH 3 COO − + H +
Λ 0 CH 3 COOH = λ 0 CH 3 COO − + λ 0 H +
= 40.9 + 349.6
Λ 0 CH 3 COOH = 390.5 Sm 2 ∕ mol
(b) Device used for the production of electricity from energy released during spontaneous chemical reaction and the use of electrical energy to bring about a chemical change.
The reaction gets reversed / It starts acting as an electrolytic cell & vice - versa.
(b)
OR
(a)
(b) Device used for the production of electricity from energy released during spontaneous chemical reaction and the use of electrical energy to bring about a chemical change.
The reaction gets reversed / It starts acting as an electrolytic cell & vice - versa.
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