How much heat does a freezer need to remove from 1kg of water at 40°C to make ice at 0°C? (You will need to use the specific heat of water to drop the temperature first, before trying to make the phase change!) Show your work.

Question

Julius Crane

Physics

28 October, 08:37

How much heat does a freezer need to remove from 1kg of water at 40°C to make ice at 0°C? (You will need to use the specific heat of water to drop the temperature first, before trying to make the phase change!) Show your work.

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Answers (1)

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Jimmy Guzman · Answer 1

Q = m c Δt

heat withdrawn to lower temperature by 40° C

Q = 1 X 1000 X 40 = 40,000 calories.

Q = mL

heat withdrawn to freeze water at 0°C to ice

= 1 x 80000 = 80,000 calories

total heat to be withdrawn = 120,000 calories. = 120,000 x 4.2 = 504,000 Joules.