Statement (A): The potential of the hydrogen electrode in a solution of
pH=10 at 298 K .
The potential of a hydrogen electrode can be calculated using the Nernst equation for the hydrogen electrode:
E=E⊖−log[H+]At standard conditions
E⊖=0, and
[H+]is calculated from the pH :
pH=10⟹[H+]=10−10Substitute into the Nernst equation:
E=−0.0591×log(10−10)=−0.59VStatement A is correct.
Statement (B): Limiting molar conductivity of
Ca2+ and
Cl−are 119 and
76Scm2mol−1 respectively.
The limiting molar conductivity of
CaCl2 is the sum of the molar conductivities of
Ca2+ and two
Cl−ions:
λCaCl2∘=λCa2+∘+2λCl−∘Substitute the given values:
λCaCl2∘=119+2(76)=119+152=271Scm2mol−1The statement given as
195Scm2mol−1 is incorrect.
Statement (C): Relationship between
KC and
Ecell ⊖.
The relationship between the standard cell potential and the equilibrium constant is given by the Nernst equation:
Ecell ⊖=lnKCConverting natural log to base-10 log:
Ecell ⊖=logKCThe statement is correctly stated.
Conclusion
Based on the analysis, the correct statements are
A and
C.
