Multiple choice

2gm of steam condenses when passed through 40gm of water initially at 25°C. If the latent heat of vaporization of water is 540kcal/kg, what is the final temperature of the mixture?

  1. 54.3°

  2. 36.1°

  3. 68.2°

  4. 100°
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A Correct answer
Explanation

Heat released by 2g steam condensing: 2g * 540 cal/g = 1080 cal. Heat absorbed by 40g water to reach T: 40g * 1 * (T - 25). Heat released by 2g water cooling from 100 to T: 2g * 1 * (100 - T). Total heat equation: 1080 + 2(100 - T) = 40(T - 25). 1080 + 200 - 2T = 40T - 1000. 2280 = 42T. T = 2280 / 42 = 54.28.

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