Question 17
Change of State and VapoursWhat is the difference in the amount of heat given out by 4 kg of steam and 4 kg of water when both are cooled from 100°C to 80°C? [The specific latent heat of steam is 2,260,000 J kg−1, specific heat capacity of water is 4200 J kg−1 K−1]
- A.4200 J
- B.2,260,000 J
- C.9,040,000 J
- D.9,380,000 J
Show the answer and explanation
Answer: C (9,040,000 J)
Explanation
Both give out the same heat cooling from 100°C to 80°C as water; the steam gives out extra latent heat when it condenses: 4 × 2 260 000 = 9 040 000 J.