In the given irreversible reaction, `H_2O+HCl to H_3O^++Cl^-` the species that acts as Bronsted base is

Options

A. `H_2O`
B. `HCl`
C. `H_3O^+`
D. `Cl^-`

Answer

To determine which species acts as a Brønsted base in the reaction \( H_2O + HCl \rightarrow H_3O^+ + Cl^- \), we need to analyze the roles of each species involved in the reaction.

### Step-by-Step Solution:

1. **Identify the Reaction Components**:
The reaction involves water (\( H_2O \)), hydrochloric acid (\( HCl \)), hydronium ion (\( H_3O^+ \)), and chloride ion (\( Cl^- \)).

2. **Understand Brønsted Acid-Base Theory**:
According to Brønsted-Lowry theory, an acid is a proton (H\(^+\)) donor, and a base is a proton acceptor.

3. **Determine the Role of Hydrochloric Acid (HCl)**:
In this reaction, \( HCl \) donates a proton (H\(^+\)) to another species. Therefore, \( HCl \) acts as a Brønsted acid.

4. **Analyze the Role of Water (H2O)**:
Water (\( H_2O \)) accepts the proton (H\(^+\)) from \( HCl \). When it accepts the proton, it transforms into \( H_3O^+ \). This means that water is acting as a proton acceptor.

5. **Identify the Brønsted Base**:
Since water accepts the proton, it is classified as a Brønsted base in this reaction.

6. **Conclusion**:
The species that acts as a Brønsted base in the given reaction is \( H_2O \).

### Final Answer:
The species that acts as a Brønsted base is \( H_2O \).

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