(Solution) - a Estimate the liquefaction coefficient for helium by treati -(2025 Original AI-Free Solution)

Paper Details

(a) Estimate the liquefaction coefficient ? for helium by treating it as a van der Waals gas. Select the van der Waals coefficients a and b in such a way that fur one mole 2Wb is the actual molar volume of liquid helium and that 2u/b is the actual inversion temperature Use the data in Table 12.1. Approximate the denominator in (7) by settling

Hout ? Htiq ? ?h + 5/2 (?in ? ?tiq),
where ?H is the latent heat of vaporization of liquid helium. (Explain how this approximation arises if on treats the expanded gas as an ideal). The resulting expression gives ? a function of the molar volumes Vin and Vout. Convert to pressures by approximating the Vs via the ideal gas law,
(b) Insert numerical values for T = 15 K and compare withfigure