Ice at -20°C is added to 50 g of water at 40° C. When the temperature of the mixture reaches 0°C, it is found that 20 g of ice is still unmelted. The amount of ice added to the water was close to (Sp…

Question

Ice at -20°C is added to 50 g of water at 40° C. When the temperature of the mixture reaches 0°C, it is found that 20 g of ice is still unmelted. The amount of ice added to the water was close to (Specific heat of water = 4.2J/g/°C Specific heat of Ice = 2.1 J/g/°C. Heat of fusion of water at 0°C = 334 J/g

Accepted Answer

Correct answer: B. (b) Heat lost by water ΔQ = msΔT = 50× 1 × 40 = 2000 cal Let mass of ice = m Heat gain by ice ΔQ = m × 12 × 20 + (m – 20) × 80 = 10 m + 80 m – 1600 = 90 m – 1600 Heat gain = Heat lost 90 m – 1600 = 2000 m = 40 gm

Solution

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