How many calories are required to heat 40 gram of argon from 40⁰C to 100⁰C at constant volume? ( R = 2 cal/mol.K)

Options

(a) 120
(b) 2400
(c) 1200
(d) 180

Correct Answer:

180

Explanation:

The molar heat capacity is the heat required to raise the temperature of one mole of the gas by 1°C.
Molar heat capacity at constant volume : C(v) = (3 / 2) R
40 gram of argon means 1 mole.
Here, C(v) = 3 cal
Thus the heat required to raise the temperature by 60°C is
60 × 3 = 180 cal.