1 kg of 0.75 molal aqueous solution of sucrose can be cooled up to −4°C before freezing. The amount of ice (in g) that will be separated out is . (Nearest integer). [Given: ]

Question

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Strategy:
 When the solution is cooled, ice separates out, which increases the concentration of the remaining solute. Use the final freezing point to find the molality of the concentrated solution, and then determine how much water is needed to maintain that molality.

Step 1: Initial composition
- Molality . Total mass of solution = 1 kg.
- Let  be mass of water in kg. Molar mass of sucrose = 342.
- .
- .
- .
- .

Step 2: Final State at -4°C
.

Step 3: Calculate remaining solvent ()

Step 4:

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