Question

Which of the following is true for the free-energy change of a reaction (\(\Delta G\)) catalyzed by an enzyme?

• A. A reaction can take place spontaneously only if \(\Delta G\) is negative.
• B. In a system at equilibrium, there is a net change in the concentrations of the products and reactants and \(\Delta G\) is positive.
• C. The \(\Delta G\) of a reaction is dependent on the path of the transformation.
• D. The \(\Delta G\) provides information about the rate of a reaction.

Hint:

• \(\Delta G\) → Spontaneity (thermodynamics)
• Rate → Controlled by activation energy, not \(\Delta G\)

Answer 1

The Correct Option is A

Concept: Free energy change (\(\Delta G\)) determines the spontaneity of a reaction, not its rate.
• \(\Delta G < 0\) → Spontaneous reaction
• \(\Delta G = 0\) → Equilibrium
• \(\Delta G > 0\) → Non-spontaneous reaction

Step 1: Analyzing each statement.

• (A): True — spontaneity requires negative \(\Delta G\).
• (B): False — at equilibrium, \(\Delta G = 0\) and no net change occurs.
• (C): False — \(\Delta G\) is a state function, independent of path.
• (D): False — \(\Delta G\) does not indicate reaction rate (kinetics).

Step 2: Selecting the correct answer.
Only statement (A) is correct.