`CH_(3)COOC_(2)H_(5)(aq)+H_(2)O(l)overset(H^(+)(aq))toCH_(3)COOH(aq)+C_(2)H_(5)OH(aq)`. What type of reaction is this?

Options

A. unimolecular elementary
B. Pseudo first order
C. Zero order reaction must be a complex reaction
D. Second order

Answer

To determine the type of reaction represented by the equation:

\[ \text{CH}_3\text{COOC}_2\text{H}_5(aq) + \text{H}_2\text{O}(l) \overset{\text{H}^+(aq)}{\rightarrow} \text{CH}_3\text{COOH}(aq) + \text{C}_2\text{H}_5\text{OH}(aq) \]

we can follow these steps:

### Step 1: Identify the Reaction Type
The reaction involves an ester (ethyl acetate, \(\text{CH}_3\text{COOC}_2\text{H}_5\)) reacting with water (\(\text{H}_2\text{O}\)) in the presence of an acid catalyst (\(\text{H}^+\)). This process results in the formation of acetic acid (\(\text{CH}_3\text{COOH}\)) and ethanol (\(\text{C}_2\text{H}_5\text{OH}\)). This is a classic example of ester hydrolysis.

### Step 2: Analyze the Conditions
The hydrolysis occurs under acidic conditions, which means that the reaction is facilitated by the presence of an acid catalyst. In this case, the concentration of water is significantly higher than that of the ester, making it effectively constant throughout the reaction.

### Step 3: Determine the Order of the Reaction
In reactions where one reactant is in excess (like water in this case), the reaction can be simplified. The rate of the reaction can be expressed in terms of the concentration of the limiting reactant (the ester). Since the concentration of water remains constant, it can be incorporated into the rate constant.

The rate law for this reaction can be expressed as:

\[ \text{Rate} = k' [\text{CH}_3\text{COOC}_2\text{H}_5] \]

Where \(k'\) is the modified rate constant that includes the constant concentration of water. This indicates that the reaction is first-order with respect to the ester.

### Step 4: Conclude the Reaction Type
Since the reaction is first-order with respect to the ester but involves water in excess, it is classified as a **pseudo first-order reaction**.

### Final Answer
The type of reaction is **pseudo first-order reaction**.

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