The mass of NaCl required to prepare 0.6 m aqueous solution in 1kg water is

Options

A. 25g
B. 18g
C. 35g
D. None of these

Explanation

To find the mass of NaCl required to prepare a 0.6 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:
\[ \text{Molality (m)} = \frac{\text{Number of moles of solute}}{\text{Mass of solvent (kg)}} \]

### Step 2: Identify the given values
From the question, we have:
- Molality (m) = 0.6 m
- Mass of solvent (water) = 1 kg

### Step 3: Calculate the number of moles of NaCl
Using the definition of molality, we can rearrange the formula to find the number of moles of NaCl:
\[ \text{Number of moles of NaCl} = \text{Molality} \times \text{Mass of solvent (kg)} \]
Substituting the known values:
\[ \text{Number of moles of NaCl} = 0.6 \, \text{mol/kg} \times 1 \, \text{kg} = 0.6 \, \text{moles} \]

### Step 4: Calculate the mass of NaCl
To find the mass of NaCl, we use the molar mass of NaCl. The molar mass of NaCl is approximately 58.5 g/mol. The formula to find mass is:
\[ \text{Mass} = \text{Number of moles} \times \text{Molar mass} \]
Substituting the values:
\[ \text{Mass of NaCl} = 0.6 \, \text{moles} \times 58.5 \, \text{g/mol} \]
Calculating this gives:
\[ \text{Mass of NaCl} = 35.1 \, \text{grams} \]

### Conclusion
Thus, the mass of NaCl required to prepare a 0.6 molal aqueous solution in 1 kg of water is approximately **35 grams**.

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