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/g-mol-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}_{p}}-{{C}_{V}}=R=2\cdot \frac{cal}{gm\text{-}mol\text{-}K} $ which is correct for option (a) and . 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 (a) is correct because $ {{\left( \frac{{{C}_{p}}}{{{C}_{V}}} \right)}_{mono}}=\frac{5}{3} $