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A 15 g mass of nitrogen gas is enclosed in a vessel at a temperature 27°C. A amount of heat transferred to the gas, so that rms velocity of molecules is doubled, is about: [Take R = 8.3 J/K mole]
- 10 kJ
- 0.9 kJ
- 14 kJ
- 6 kJ
Correct answer: 10 kJ
Solution
n = 15/28 mol. Doubling v_rms quadruples T (v ~ sqrt(T)), so dT = 4*300 - 300 = 900 K. For diatomic N2, Cv = (5/2)R, giving Q = (15/28)(2.5*8.3)(900) ~ 10 kJ.
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