Question

Rate constant \( K \) of a reaction has least value at

• A. High T and high \( E_a \)
• B. High T and low \( E_a \)
• C. Low T and low \( E_a \)
• D. Low T and high \( E_a \)

Hint:

The rate constant decreases with decreasing temperature and increasing activation energy according to the Arrhenius equation.

Answer 1

The Correct Option is D

The rate constant \( K \) of a reaction is related to temperature and activation energy by the Arrhenius equation: \[ K = A e^{-\frac{E_a}{RT}} \] Where: - \( A \) is the pre-exponential factor,
- \( E_a \) is the activation energy,
- \( R \) is the universal gas constant,
- \( T \) is the temperature. From this equation, we can deduce that for the rate constant \( K \) to be at its least value, the temperature \( T \) should be low and the activation energy \( E_a \) should be high. Therefore, the correct answer is Low T and high \( E_a \), as these conditions result in the lowest rate constant.