The order and molecularity of the chain reaction, `H_(2(g))+Cl_(2(g)) overset(hv)to HCl`

Options

A. 2, 0
B. 0, 2
C. 1, 1
D. 3, 0

Answer

To determine the order and molecularity of the chain reaction \( H_2(g) + Cl_2(g) \overset{hv}{\rightarrow} HCl(g) \), we can follow these steps:

### Step 1: Understanding Molecularity
Molecularity refers to the number of reactant molecules involved in an elementary reaction step. For this reaction, we can see that two different molecules, \( H_2 \) and \( Cl_2 \), are reacting together. Therefore, the molecularity of this reaction is 2, as it involves two reactant molecules.

### Step 2: Understanding Order
Order of a reaction is determined from the rate law, which is derived from experimental data. It is the sum of the powers of the concentration terms in the rate expression. In this case, the reaction is a chain reaction and is photochemical, meaning it occurs under the influence of light.

### Step 3: Determining the Rate Law
For the reaction \( H_2 + Cl_2 \rightarrow HCl \), the rate law can be determined experimentally. In many cases, for chain reactions, the rate does not depend on the concentrations of the reactants. If the rate of the reaction is found to be independent of the concentrations of \( H_2 \) and \( Cl_2 \), then the order of the reaction is zero.

### Step 4: Conclusion
Based on the experimental findings:
- The molecularity of the reaction is 2 (since two molecules are involved).
- The order of the reaction is 0 (since the rate does not depend on the concentration of the reactants).

### Final Answer
- **Order of the reaction**: 0
- **Molecularity of the reaction**: 2