Cooling 100 kg of a 30 wt% aqueous Na2SO4 solution yields Na2SO4.10H2O crystals, leaving a 10% solute concentration in the remaining solution. What is the crystal weight________________?
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Answer: D. 58.65
Explanation
Cooling the sodium sulfate solution causes crystallization of the decahydrate. Material balance equations account for solute mass across the phase change. Solving these simultaneous mass balances yields fifty eight point sixty five kilograms. Crystallization separates solutes from solutions by cooling or evaporating. Sodium sulfate forms a stable decahydrate crystal structure below certain temperatures. Remaining mother liquor retains the specified final solute concentration.
Chemical manufacturing plants use crystallization to purify inorganic salts. Material balance calculations are fundamental to chemical process design. Accurate yield predictions ensure chemical reactors and crystallizers are sized right. Option A underestimates the crystal yield based on incorrect mass balances. Option B represents an intermediate calculation error during solvent evaporation. Option C is incorrect because the exact mass balance calculation gives 58.65.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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