一道物理化学的题目（物理化学好的并且英语不烂的进）

Question

(物化学的的全英文的，所以~~~~不废话了，上题目）
A sample of 5.0mol CO2 is originally confined in 15L at 280K and then undergoes adiabatic expansion against a constant pressure of 78.5Kpa until the volume has increased by a factor of 4.0.Calculate q, w ,ΔT,ΔU andΔH. (the final pressure of the gas is not necessarily 78.5Kpa)

特别问下"the volume has increased by a factor of 4.0”意思是增加四倍么还是别的什么意思?
还有CO2的等容热容是能查到的物理量么，怎么我翻附录没有？？？

拜托了！！！

Answer 1

In an adiabatic process, q = 0 . Work against a constant external pressure is
w = −pexV =−(78.5 × 103 Pa) × (4 × 15 − 15) L/1000 Lm−3= −3.5 × 103 J
U = q + w = −3.5 × 103 J

w = CV T = n(Cp,m − R)T
so T = w/n(Cp,m − R)
T =−3.5 × 103 J/(5.0 mol) × (37.11 − 8.3145)JK−1 mol−1= −24K
H = U +(pV ) = U + nRT,= −3.5 × 103 J + (5.0 mol) × (8.3145 JK−1 mol−1
) × (−24K) = −4.5 × 103 J
就是4倍的意思！！一个factor让我以为是体积膨胀系数呢。。。被坑了。。这本书网上有答案详解的。CO2等容热容是28.8