InterviewSolution
Saved Bookmarks
| 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. |
|