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 can follow these steps:

### Step-by-Step Solution:

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

2. **Define Brønsted Acids and Bases**:
- A Brønsted acid is a substance that donates a proton (\( H^+ \)).
- A Brønsted base is a substance that accepts a proton (\( H^+ \)).

3. **Analyze the Role of Each Species**:
- **Hydrochloric Acid (\( HCl \))**: In the reaction, \( HCl \) donates a proton to \( H_2O \), forming \( Cl^- \). Therefore, \( HCl \) acts as a Brønsted acid.
- **Water (\( H_2O \))**: Water accepts a proton from \( HCl \) and is converted into \( H_3O^+ \). Thus, \( H_2O \) acts as a Brønsted base.

4. **Conclusion**:
- The species that acts as the Brønsted base in this reaction is \( H_2O \).

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