EK 1001 Chemistry #927

[techfan]

Question says: Suppose the amount of material undergoing an oxidation-reduction reaction doubles, but all other conditions remain the same. Which of the following also doubles?
I.Free energy change
II.Total charge flow
III. Potential

A. I
B. II
C. I & II
D. II & III
Ans: C
Explanation: Potential is defined as energy per unit charge, and thus when I and II double, III remains the same,

It also feels like they left off the first part of the explanation.

What is free energy change? I thought it was Gibbs free energy (delta G) and assumed that delta G=delta G (under standard conditions) + RT*ln(Q)

where Q=[products]/[reactants] and if you double the reactants delta G would go down, but not by double since ln is an exponential function.

Also what is total charge flow? Is that simply the amount of electrons that would be consumed in the reaction?

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[chemtopper]

Question says: Suppose the amount of material undergoing an oxidation-reduction reaction doubles, but all other conditions remain the same. Which of the following also doubles?
I.Free energy change
II.Total charge flow
III. Potential

A. I
B. II
C. I & II
D. II & III
Ans: C
Explanation: Potential is defined as energy per unit charge, and thus when I and II double, III remains the same,

It also feels like they left off the first part of the explanation.

What is free energy change? I thought it was Gibbs free energy (delta G) and assumed that delta G=delta G (under standard conditions) + RT*ln(Q)

where Q=[products]/[reactants] and if you double the reactants delta G would go down, but not by double since ln is an exponential function.

Also what is total charge flow? Is that simply the amount of electrons that would be consumed in the reaction?

Charge flow is amount of electrons transferred and 1farady = 96500C = Charge on 1mole of electrons.
Delta G and amount of charge are extensive properties and are dependent on the amount.Like one mole Cu2+ will gain two moles of electrons so the charge is 2X96500C .One mole of electrons = 96500C (charge)
However if we make it 2 moles of Cu2+ then it will gain 4moles of electrons so charge will be 4X96500C
delta G =deltaG(standard) + nRT lnQ
hence it is dependent on moles
If delta G for one mole is XkJ
then for two moles it will be 2XkJ
However potential is the internal property or intensive property of matter and is independent on the quantity of the matter.