In the reaction `HCl + H_(2)O to H_(3)^(+)O +Cl^(-)`

Options

A. `H_(2)O` is the conjugate base of HCl acid
B. `Cl^(-)` is the conjugate base of HCl acid
C. `Cl^(-)` is the conjugate acid of base
D. `H_(3)O^(+)` is the conjugate base of HCl

Explanation

To analyze the reaction \( \text{HCl} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{Cl}^- \), we can follow these steps:

### Step 1: Identify the reactants and products
In this reaction, we have hydrochloric acid (HCl) and water (H₂O) as reactants. The products formed are the hydronium ion (\( \text{H}_3\text{O}^+ \)) and the chloride ion (\( \text{Cl}^- \)).

### Step 2: Determine the acid and base
In the context of the Brønsted-Lowry theory:
- An acid is a substance that donates a proton (H⁺).
- A base is a substance that accepts a proton (H⁺).

Here, HCl donates a proton to water, making HCl the acid and water the base.

### Step 3: Identify the conjugate base and conjugate acid
- The conjugate base of an acid is what remains after the acid has donated a proton. In this case, when HCl donates a proton, it forms the chloride ion (\( \text{Cl}^- \)), which is the conjugate base of HCl.
- The conjugate acid of a base is what is formed when the base accepts a proton. Water (H₂O) accepts a proton to form the hydronium ion (\( \text{H}_3\text{O}^+ \)), which is the conjugate acid of water.

### Step 4: Conclusion
From the analysis:
- HCl is the acid, and its conjugate base is \( \text{Cl}^- \).
- Water is the base, and its conjugate acid is \( \text{H}_3\text{O}^+ \).

Thus, the correct identification is that \( \text{Cl}^- \) is the conjugate base of HCl.

### Final Answer:
The conjugate base of HCl in the reaction \( \text{HCl} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{Cl}^- \) is \( \text{Cl}^- \).

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