For an infinitely dilute aqueous solution molality will be equal to :

Options

A. formality
B. molarity
C. mole fraction
D. ppm

Answer

To solve the question about the relationship between molality and an infinitely dilute aqueous solution, we can follow these steps:

### Step-by-Step Solution:

1. **Define Molality**:
Molality (m) is defined as the number of moles of solute divided by the mass of the solvent in kilograms.
\[ \text{Molality (m)} = \frac{\text{moles of solute}}{\text{mass of solvent (kg)}} \]

2. **Understand Infinitely Dilute Solution**:
In an infinitely dilute solution, the concentration of the solute is very low, meaning the weight of the solute becomes negligible compared to the weight of the solvent.

3. **Density of Solution**:
For an infinitely dilute aqueous solution, the density of the solution approaches that of the solvent (water), which is approximately 1 g/mL or 1 kg/L. Therefore, we can assume:
\[ \text{Density of solution} \approx \text{Density of solvent} = 1 \text{ kg/L} \]

4. **Weight of Solution**:
The weight of the solution can be expressed as the sum of the weight of the solute and the weight of the solvent. However, since the solute is negligible in an infinitely dilute solution:
\[ \text{Weight of solution} \approx \text{Weight of solvent} \]

5. **Relate Molality and Molarity**:
Molarity (M) is defined as the number of moles of solute per liter of solution. In an infinitely dilute solution, the volume of the solution can be approximated to the volume of the solvent due to the negligible amount of solute:
\[ \text{Molarity (M)} \approx \text{Molality (m)} \]

6. **Conclusion**:
Therefore, for an infinitely dilute aqueous solution, molality will be equal to molarity. Thus, the answer to the question is that molality is equal to molarity in this case.

### Final Answer:
For an infinitely dilute aqueous solution, molality will be equal to molarity.

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