Question

Helium condenses at −268.93∘∘C and has a latent heat of vaporization of 21,000 J/kg. You start with 4.00 g of helium gas at 29.0∘∘C. The specific heat of helium is 5193 J/(kg·K) at 300 K.

1)

Calculate the amount of heat required to change the sample to liquid helium. (Express your answer to two significant figures.)

I did the following: 0.004 (5193) (29+268.93) + (0.004)(21000), but I still got the wrong answer. Any help is appreciated.

Answer 1

The amount of heat required will be negative,as we are cooling the helium.

Essentially, your answer is correct, but since we are taking heat away from the helium, or in other words, the helium is is giving out heat. the answer will be negative.