Question

30g water at 30°C is mixed with 1g of steam at 100℃. Calculate the final temperature of the mixture. Sw = 1cal/ g°C, Lvap= 540cal/g.

(a) 49.67°C

(b) 38.33°C

(c) 53.67°C

(d) 41.33°C

This question was addressed to me in an online quiz.

My question is taken from Thermal Properties of Matter in section Thermal Properties of Matter of Physics – Class 11

Answer 1

Correct option is (a) 49.67°C

The best explanation: 30*1*(T-30) = 1*540 + 1*1*(100-T)  

∴ 30T – 900 = 540 + 100 – T  

⇒ 31T = 1540   

⇒ T = 49.67°C