Effect of Catalyst

Q. A hydrogenation reaction is carried out at 500 K. If the same reaction is carried out in the presence of a catalyst at the same rate, the temperature required is 400 K. Calculate the activation energy of the reaction at 500 K, if the catalyst lowers the activation barrier by $20kJmo{l}^{-1}$.

1. $100kJmo{l}^{-1}$.
2. $80kJmo{l}^{-1}$.
3. $110kJmo{l}^{-1}$.
4. $95kJmo{l}^{-1}$.

Q. Which of the following statements regarding catalyst is not true?

1. A catalyst remains unchanged in composition and quantity at the end of the reaction.
2. A catalyst can alter the Gibbs free energy change.
3. A catalyst does not alter the equilibrium in a reversible reaction.
4. Catalysts are sometimes very specific in respect of reaction.

Q.

A catalyst is a substance which:

1. increases the equilibrium concentration of the product

2. shortens the time to reach equilibrium

3. supplies energy to the reaction

4. changes the equilibrium constant of the reaction

Q.

The energies of activation for forward and reverse reactions for $A_2+B_2\rightleftharpoons 2AB$ are $180kJmo{l}^{-1}$ and $200kJmo{l}^{-1}$ respectively. The presence of a catalyst lowers activation energy of both reactions by $100kJmo{l}^{-1}$. The enthalpy change of the reaction $(A_2+B_2\to 2AB)$ in the presence of a catalyst will be (in kJ $mo{l}^{-1}$)

1. 20

2. 300

3. 120

4. 280

Q.

The energies of activation for forward and reverse reactions for $A_2+B_2\rightleftharpoons 2AB$ are $180kJmo{l}^{-1}$ and $200kJmo{l}^{-1}$ respectively. The presence of a catalyst lowers activation energy of both reactions by $100kJmo{l}^{-1}$. The enthalpy change of the reaction $(A_2+B_2\to 2AB)$ in the presence of a catalyst will be (in kJ $mo{l}^{-1}$)

1. 20

2. 300

3. 120

4. 280

Q. A catalyst is used

1. Only for increasing the rate of a reaction
2. For altering the rate of a reaction
3. Only for decreasing the rate of a reaction
4. For making Gibbs free energy change positive