Question

The mass of a gas molecule can be computed from the specific heat at constant volume. $C_v$ for argon is $0.075kcal/kgK$. The molecular weight of an argon atom is $(R=2cal/molK)$.

• A. $40kg$
• B. $40\times {10}^{-3}kg$
• C. $20kg$
• D. $20\times {10}^{-3}kg$

Answer 1

Answer: (B)

$40\times {10}^{-3}kg$

$C_v=75cal/kgK=75\times M_{o}cal/molK=\frac{3}{2}R$

$⟹75M_o=\frac{3}{2}\times 2kg$

$⟹M_o=0.04kg=40\times {10}^{-3}kg$