The mass of NaCl required to prepare 0.08 m aqueous solution in 1kg water is

Options

A. 1g
B. 2.48g
C. 4.68g
D. None of these

Explanation

To find the mass of NaCl required to prepare a 0.08 molal aqueous solution in 1 kg of water, we can follow these steps:

### Step 1: Understand the definition of molality
Molality (m) is defined as the number of moles of solute per kilogram of solvent. The formula is:

\[ \text{Molality (m)} = \frac{\text{Number of moles of solute}}{\text{Mass of solvent in kg}} \]

### Step 2: Identify the given values
From the question, we have:
- Molality (m) = 0.08 m
- Mass of solvent (water) = 1 kg

### Step 3: Rearrange the formula to find the number of moles of solute
We can rearrange the molality formula to find the number of moles of solute:

\[ \text{Number of moles of solute} = \text{Molality} \times \text{Mass of solvent in kg} \]

Substituting the values:

\[ \text{Number of moles of NaCl} = 0.08 \, \text{m} \times 1 \, \text{kg} = 0.08 \, \text{moles} \]

### Step 4: Calculate the mass of NaCl using its molar mass
The molar mass of NaCl is approximately 58.5 g/mol. We can calculate the mass of NaCl required using the formula:

\[ \text{Mass of solute} = \text{Number of moles} \times \text{Molar mass} \]

Substituting the values:

\[ \text{Mass of NaCl} = 0.08 \, \text{moles} \times 58.5 \, \text{g/mol} \]

Calculating this gives:

\[ \text{Mass of NaCl} = 4.68 \, \text{grams} \]

### Conclusion
The mass of NaCl required to prepare a 0.08 molal aqueous solution in 1 kg of water is **4.68 grams**.

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