A proposed mechanism is: Step 1: H2(g) + ICl(g) → HI(g) + HCl(g) (slow) Step 2: HI(g) + ICl(g) → I2(g) + HCl(g) (fast) Which of the following species is a catalyst? ICl HCl This mechanism has no catalyst. HI H2

This mechanism has no catalyst

Explanation:

The proposed mechanism is :

Step 1 :    (slow)

Step 2:    (fast)

The combined chemical equation will be :

A catalyst is a substance which enhances the rate of chemical reaction without being consumed in the chemical reaction. Thus catalyst gets used up in first step and gets regenerated in second.

HI is formed as an intermediate as it gets formed in first step and gets used up in the second step.

Here there is no substance which is used as a catalyst.