The correct answer is (4) Rate of reaction decreases with rise in temperature.
Let's discuss each statement and why option 4 is incorrect:
1. In endothermic reactions, reactant molecules have lower energy than product molecules:
This statement is correct. Endothermic reactions absorb energy from the surroundings, and as a result, the products have higher energy than the reactants.
2. Energy of the activated complex is higher than the energy of reactants:
This statement is correct. The activated complex (or transition state) is a high-energy intermediate state that forms during a chemical reaction. It has higher energy than both the reactants and the products.
3. Energy of activation of the reaction is different from the energy of activation with a catalyst for the same reaction:
This statement is correct. A catalyst lowers the activation energy of a reaction, making it easier for the reaction to occur. The presence of a catalyst does not change the overall energy change of the reaction; it just provides an alternative reaction pathway with a lower activation energy.
4. Rate of reaction decreases with the rise in temperature:
This statement is incorrect. In general, the rate of chemical reactions tends to increase with the rise in temperature. This is explained by the Arrhenius equation, which shows that the rate constant of a reaction is exponentially dependent on temperature. Higher temperatures provide more energy to the reacting molecules, leading to more frequent and energetic collisions, and, consequently, an increased reaction rate.
In summary, all the statements except option 4 are correct. The rate of reaction typically increases with an increase in temperature. |
