Question

Consider the following reaction at 298K. Hg (aq)+2 Cu (aq) Hg ()+2 Cu(a) Which of the following statements are correet? Choose all that apply. On 1 mol electrons Eoell 0 The reaction is reactant-favored. delta Go < 0

Answer 1

As per standard reduction potentials Cu²⁺ + 2e^- -----------> Cu ; E^o = 0.34 V,  

Cu²⁺ + e^- -----------> Cu⁺ , E^o = 0.16 V,

Hg²⁺ + 2e^- -----------> Hg ; E^o = 0.85 V,

Answer a)

Equation involved is Hg²⁺ + 2Cu⁺  -----------> Hg + 2Cu²⁺

E^o = 0.85 - 0.16 = 0.69 V

303R logK EO

Correct statements are:

K > 1 (because E^o is positive, so K is also positive i.e more than 1)

delta G^o < 0 (because G^o = -nFE^o, as E^o is positive, G^o will be negative)

Incorrect statements are so, because

n = 1, (it is actually n = 2)

E^o < 0 (it is actually E^o > 0)

Reaction is reactant favored (because K > 1, reaction is product favored).

Answer 2

Equation involved is Cu²⁺ + Hg -----------> Cu + Hg²⁺

E^o = 0.34 - 0.85 = - 0.51 V

303R logK EO

Correct statements are:

E^o < 0 (as calculated above)

n = 2

K < 1 (because E^o < 0, so log K will be negative and K < 1)

Incorrect statements are

delta G^o < 0 (because G^o = -nFE^o, as E^o is negative, G^o will be positive)

Reaction is product favored (because K < 1, reaction is reactant favored).

The answers can be predicted without considering reduction potential values by the fact that "Hg is less reactive than copper as per reactivity series"