How many moles of HCl are present in 1 litre of 1 M HCl solution ?

Answer

To determine how many moles of HCl are present in 1 litre of a 1 M HCl solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Molarity**: Molarity (M) is defined as the number of moles of solute (in this case, HCl) per liter of solution. The formula for molarity is:
\[ \text{Molarity (M)} = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}} \]

2. **Identify Given Values**: From the question, we know:
- Molarity (M) = 1 M (1 molar)
- Volume of solution = 1 L (1 litre)

3. **Set Up the Equation**: We can rearrange the molarity formula to find the number of moles of solute:
\[ \text{Number of moles of solute} = \text{Molarity} \times \text{Volume of solution} \]

4. **Substitute the Values**: Now, substitute the known values into the equation:
\[ \text{Number of moles of HCl} = 1 \, \text{M} \times 1 \, \text{L} \]

5. **Calculate**: Perform the multiplication:
\[ \text{Number of moles of HCl} = 1 \, \text{mole} \]

6. **Conclusion**: Therefore, the number of moles of HCl present in 1 litre of a 1 M HCl solution is:
\[ \text{1 mole} \]

### Final Answer:
1 mole of HCl.

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