1.

A refrigerator converts 5 kg of water at 40°C into ice at 0°C. Find the total energy released in Joules.

Answer»

m = 5 kg = 5000 g The heat energy released to convert 5 kg of water at 40°C to 5 kg of water at 0°C.

Q1 = ms∆T 

= 5000 × 1 × (40 – 0) 

= 5000 × 40 = 200000 cal [s = 1 cal/g-°C for water] 

The heat energy released to convert 5 kg of water at 0°C to 5 kg of ice at 0°C. 

Q2 = mLf

= 5000 × 80 = 400000 cal [∵ Lf = 80 cal/g] 

Total energy released = 200000 + 400000 

= 600000 cal 

= 600 kcal 

= 142.86 kJ.



Discussion

No Comment Found

Related InterviewSolutions