Question

The following sets of values for $C_{V}$ and $C_{P}$ of a gas has been reported by different students. The units are cal/gm-mole-K. Which of these sets is most reliable

• A. $C_{v} = 3,C_{p} = 5$
• B. $C_{V} = 4,C_{P} = 6$
• C. $C_{v} = 3,C_{p} = 2$
• D. $C_{V} = 3,C_{P} = 4.2$

Answer 1

Answer: (A)

$C_{v} = 3,C_{p} = 5$

Answer 2

$C_{P} - C_{V} = R = 2.\frac{cal}{gm - mol - K}$ Which is correct for option (1) and (2). Further the ratio $\frac{C_{P}}{C_{V}}( = \gamma)$ should equal to some standard value corresponding to that of either, mono, di, or triatomic gases. From this point of view option (1) is correct because $\left( \frac{C_{P}}{C_{V}} \right)_{mono} = \frac{5}{3}$