[Pranav]

Question:
The cell potential for the unbalanced chemical reactino:
Hg₂⁺²+NO₃^-+H₃O⁺ Hg²⁺+HNO₂+H₂O+e^-
is balanced under standard conditions in the electrochemical cell shown in the diagram were 0.02 V.

http://i45.tinypic.com/iz9s2p.png

Q1) Choose the correct statement for the given cell diagram
A)Compartment X has less pH than compartment Y
B)Y compartment has acidic solution
C)Current will flow from X->Y through internal supply
D)ΔG° for the above cell reaction is more than 1 at equlibrium

Q2)Equilibrium constant for cell reaction is:
A)10^(3/2)
B)e^(-3/2)
C)e^(-2/3)
D)10^(2/3)

Q3)If same amount of charge (which is required for formation of 0.1 mol of HNO₂ in the above given cell) used for electrolysis 0.1 M, 1L aqueous solutino of CuSO₄, then the volume liberated at STP will be:
A)2.24 L
B)5.6 L
C)22.4 L
D)11.2 L

Before answering the questions, I would like to know if I am understanding the set-up correctly.

I am not sure where to start. I began with balancing the given chemical equation. This is what I get after balancing the equation:
Hg₂⁺²+NO₃^-+3H⁺ 2Hg²⁺+HNO₂+H₂O
Is this correct?

Since Hg₂²⁺ is being reduced and reduction takes place at cathode, it should be placed in X compartment and NO₃^- in the Y compartment. Is this right?

As for the current, do I need to take the conventional direction i.e. opposite to the direction of motion of electron. I haven't done too many questions on electrochemistry so I am not sure about this convention. 

Any help is appreciated. Thanks!

[Pranav]

Anyone?

[Borek]

Hg₂⁺²+NO₃^-+3H⁺ 2Hg²⁺+HNO₂+H₂O

This is slightly different from what you started with, but yes, it is correctly balanced.

Hg₂²⁺ is being reduced

It is not!

As for the current, do I need to take the conventional direction i.e. opposite to the direction of motion of electron.

Yes.

[Pranav]

Hg₂⁺²+NO₃^-+3H⁺ 2Hg²⁺+HNO₂+H₂O

This is slightly different from what you started with, but yes, it is correctly balanced.

Will that make any difference if I use it solve the questions or do I need to stick to the original equation mentioned in the problem statement?

Hg₂²⁺ is being reduced

It is not!

Thanks for the check. So, NO₃^- should be placed in the X compartment? But then HNO₂ is produced in the X compartment and it becomes more acidic which is opposite to the answer of Q1). The answer says that Y compartment has acidic solution.

As for the current, do I need to take the conventional direction i.e. opposite to the direction of motion of electron.

Yes.

Thank you, this eliminates option B for Q1.

[Borek]

Will that make any difference if I use it solve the questions or do I need to stick to the original equation mentioned in the problem statement?

Should not.

Thanks for the check. So, NO₃^- should be placed in the X compartment? But then HNO₂ is produced in the X compartment and it becomes more acidic which is opposite to the answer of Q1). The answer says that Y compartment has acidic solution.

Sorry, you are not going to drag me into discussion of sign conventions. I don't feel confident enough and I don't want to give bad advice.

I think you should start checking standard potentials for both half reactions - the one with the higher potential should end at a + terminal.

Q1-D - are you sure it was about ΔG° being compared to 1, not to 0?

[Pranav]

I think you should start checking standard potentials for both half reactions - the one with the higher potential should end at a + terminal.

I just checked the standard potentials for the half reactions from wikipedia. For Hg₂²⁺, its negative so it should end up in the X compartment and NO₃^3- in the Y compartment. But this question is from my test paper, am I really supposed to remember such a long list of electrode potentials?

Q1-D - are you sure it was about ΔG° being compared to 1, not to 0?

Yes, I checked it, it is compared to 1.