Question

About positive and negative catalysts, which of the following statements is incorrect?
A) Positive catalyst lowers the energy of activation
B) Negative catalyst decreases the energy of activation
C) Positive catalyst increases the rate of reaction
D) Negative catalyst functions to remove active intermediates

Answer 1

Hint: A catalyst can be defined as a substance that is added to a reaction to increasing the reaction rate without getting consumed in the process. One can analyze all the statements given and decide which one is incorrect.

Complete step by step answer:
1) First of all let's learn about the catalyst, which is used as a chemical species which increases or decreases the reaction rate but without taking part in the reaction which means it doesn’t lose or gain any atoms or groups from its chemical structure.
2) The catalyst is a species that speeds up a reaction rate by reducing the energy of activation or by making changes in the path of the reaction mechanism.
3) Now let’s analyze the statements given one by one. The statement 1st states that a positive catalyst lowers the energy of activation which is correct as a positive catalyst decreases activation energy by accepting a smaller path which also increases the rate of reaction.
4) The statement 2nd states that a negative catalyst decreases the energy of activation which is incorrect as a negative catalyst increases the energy of activation making a decrease in the rate of reaction. Hence, this statement is INCORRECT.
5) The statement 3rd states that a positive catalyst increases the rate of reaction which is correct as the positive catalyst lowers the energy of activation.
6) The statement 4th states that negative catalyst functions to remove active intermediates which is correct as by removing the active intermediates it increases the energy of activation needed for the reaction.
7) Therefore, the statement negative catalyst decreases the energy of activation is incorrect which shows option B as a correct choice.
Thus option B is the correct answer.


Note:
A negative catalyst increases the energy of activation by taking the reaction by a longer alternative path. The negative catalyst combines with reactant molecules which decreases the number of initial colliding reactant molecules. A positive catalyst takes a smaller path and doesn’t react with reactant molecules.