Question

Which of the following statements is not correct ?

• A. \(\Delta G^{\circ}\) is an extensive property.
• B. \(E^{\circ}\) cell is an intensive property.
• C. For a chemical reaction to be spontaneous \(\Delta G\) must be \(-\text{ve}\).
• D. Electrical work is equal to \(\Delta G\)

Hint:

Gibbs energy depends on the amount of substance, while cell potential does not. Electrical work equals minus delta G.

Answer 1

The Correct Option is D

Step 1: Recall the relations
The standard Gibbs energy and cell potential are linked by \(\Delta G^{\circ} = -nFE^{\circ}_{cell}\). The maximum electrical work obtained from a cell equals \(-\Delta G\), not \(+\Delta G\).

Step 2: Check statement (A)
\(\Delta G^{\circ}\) depends on the number of moles reacting, so it is extensive. So (A) is TRUE.

Step 3: Check statement (B)
\(E^{\circ}_{cell}\) does not change when we multiply the cell reaction by a factor, because \(n\) in the equation changes with it. So it is intensive and (B) is TRUE.

Step 4: Check statement (C)
A process is spontaneous at constant temperature and pressure when \(\Delta G < 0\). So (C) is TRUE.

Step 5: Check statement (D)
Electrical work done by the cell is \(W_{elec} = -\Delta G\), so it is the negative of \(\Delta G\), not equal to it. So (D) is FALSE.

Final Answer:
Statement D is not correct, so D is the answer. \[ \boxed{\text{(D)}\ D} \]