In a reaction involving hydrolysis of an organic chloride in presence of large excess of water eg `RCl + H_2O to ROH + HCl` Which of these is true?

Options

A. Molecularity is 2, order of reaction is also 2
B. Molecularity is 2, order of reaction is 1
C. Molecularity is 1, order of reaction is 2
D. Molecularity is 1, order of reaction is also 1

Answer

To solve the question regarding the hydrolysis of an organic chloride in the presence of a large excess of water, we will analyze the reaction step by step.

### Step 1: Write the Reaction
The given reaction is:
\[ \text{RCl} + \text{H}_2\text{O} \rightarrow \text{ROH} + \text{HCl} \]

### Step 2: Identify the Rate Law Expression
The rate of the reaction can be expressed in terms of the concentrations of the reactants. The general form of the rate law for this reaction is:
\[ \text{Rate} = k [\text{RCl}][\text{H}_2\text{O}] \]
where \( k \) is the rate constant.

### Step 3: Consider the Excess Water
Since water is present in large excess, its concentration does not change significantly during the reaction. Therefore, we can treat the concentration of water as a constant. We can redefine the rate constant to account for this:
\[ \text{Rate} = k' [\text{RCl}] \]
where \( k' = k [\text{H}_2\text{O}] \).

### Step 4: Determine the Order of the Reaction
The order of a reaction is defined as the sum of the powers of the concentrations in the rate law. In this case, since the rate law simplifies to:
\[ \text{Rate} = k' [\text{RCl}] \]
the reaction is first order with respect to RCl. Therefore, the overall order of the reaction is:
- **Order = 1**

### Step 5: Determine the Molecularity of the Reaction
Molecularity refers to the number of reactant molecules involved in an elementary reaction. In this case, we have:
- One molecule of RCl
- One molecule of H2O

Thus, the total number of reactant molecules is:
- **Molecularity = 2**

### Step 6: Conclusion
From the analysis, we conclude that:
- The order of the reaction is 1 (pseudo first order due to excess water).
- The molecularity of the reaction is 2 (two reactants involved).

### Final Answer
The correct statement regarding the reaction is:
- **Molecularity is 2 and Order is 1.**

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