The van der Waals constant accounts for the finite volume occupied by gas molecules
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
The van der Waals constant b accounts for the finite volume occupied by gas molecules. For carbon dioxide, b=0.0427Lmol−1, and for hydrogen, b=0.0266Lmol−1. One mole of each gas is separately compressed to 1200atm at 300K in an insulated cylinder equipped with an accurate manometer and volume scale. Assume the temperature remains precisely 300K.
(a) Determine the volume that one mole of an ideal gas would occupy at 300K and 1200atm.
(b) Using the provided b values and treating all other non-ideal effects as negligible, obtain an improved estimate of the volume for each real gas under these conditions. State any assumptions you make.
(c) For each gas, calculate the percent deviation of your estimate in part (b) from the ideal volume found in part (a). Identify which gas exhibits the larger positive deviation and explain the result in terms of molecular size.