250 mL of water at 20.0 ∘C is placed in the freezer compartment of a refrigerator...

250 mL of water at 20.0 ∘C is placed in the freezer compartment of a refrigerator with a coefficient of performance of 4.00. How much heat energy is exhausted into the room as the water is changed to ice at -5.00 ∘C?

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Expert Solution

Solution:

Volume of water = 250 mL = 0.00025 m^3

=> mass =density x volume = 1000x0.000250 = 0.25 kg

Temperature of water = 20 C

oefficient of performance =4

The heat released to convert water at 20 C to ice at 0C = mcdelta t

=( 0.25)(4186)(20-0) = 20930 J

Energy to convert water at 0C to ice at 0C =mL=0.25 * 3.34x10^5 J = 83500 J

Heat to convert ice at 0C to ice at -5 C = (0.25)(2108)(5) = 2635 J

Total quantity of heat energy = Qc = 20930 +83500 +2635 = 107065 J

coefficient of performance = k = 4

k= Qc /W = > W=Qc / k =107065 /4 = 26766.25 J

Qh=W+Qc =26766.25 + 107065 = 133831 J

= 133.8 kJ

Water changes to ice at -5 C

genius_generous answered 4 months ago

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