The reaction `C_2H_5Cl+OH^(-) rarr C_2H_5OH+Cl^(-)` is

Options

A. `S_N1`
B. `S_N2`
C. `S_E1`
D. `S_E2`

Explanation

To determine the type of reaction for the given equation \( C_2H_5Cl + OH^- \rightarrow C_2H_5OH + Cl^- \), we can analyze the components and the mechanism involved in this nucleophilic substitution reaction.

### Step-by-Step Solution:

1. **Identify the Reactants and Products:**
- The reactants are ethyl chloride (\( C_2H_5Cl \)) and hydroxide ion (\( OH^- \)).
- The products are ethanol (\( C_2H_5OH \)) and chloride ion (\( Cl^- \)).

2. **Determine the Type of Reaction:**
- This reaction involves the substitution of the chlorine atom in ethyl chloride with the hydroxide ion. This is characteristic of a nucleophilic substitution reaction.

3. **Classify the Nucleophilic Substitution:**
- Nucleophilic substitution reactions can be classified as either SN1 or SN2.
- SN1 reactions typically occur with tertiary substrates and involve a two-step mechanism: formation of a carbocation followed by nucleophilic attack.
- SN2 reactions occur with primary or secondary substrates and involve a one-step mechanism where the nucleophile attacks the substrate simultaneously as the leaving group departs.

4. **Analyze the Structure of the Substrate:**
- Ethyl chloride (\( C_2H_5Cl \)) is a primary halide since the carbon attached to the chlorine is bonded to only one other carbon.
- Primary halides favor the SN2 mechanism due to less steric hindrance, allowing the nucleophile (\( OH^- \)) to attack more effectively.

5. **Conclusion:**
- Since the substrate is a primary halide and the reaction involves a direct attack by the nucleophile, the reaction follows the SN2 mechanism.

### Final Answer:
The reaction \( C_2H_5Cl + OH^- \rightarrow C_2H_5OH + Cl^- \) is an **SN2 reaction**.