Two different gases

CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures

Problem

Two different gases, neon and sulfur hexafluoride, are each brought to 320 K and compressed from 1.0 atm to 200 atm along an isotherm. Assume one mole of each gas. For reference, the van der Waals parameters are Ne: a=0.210 L2 atm mol−2a=0.210\,\text{L}^2\,\text{atm}\,\text{mol}^{-2}, b=0.0171 L mol−1b=0.0171\,\text{L}\,\text{mol}^{-1} SF6_6: a=3.59 L2 atm mol−2a=3.59\,\text{L}^2\,\text{atm}\,\text{mol}^{-2}, b=0.0562 L mol−1b=0.0562\,\text{L}\,\text{mol}^{-1} (a) Without performing numerical calculations, predict for each gas whether ZZ will be less than, greater than, or cross over 1.0 as pressure increases from 1.0 atm to 200 atm at 320 K. Justify your predictions in terms of molecular properties and the given parameters. (b) Between the two gases, identify which one will show the larger absolute deviation from Z=1Z=1 at 50 atm and explain your reasoning. (c) At approximately what pressure do you expect sulfur hexafluoride to transition from attraction-dominated to volume-dominated non-ideality along this isotherm? Outline the qualitative reasoning steps leading to your estimate.

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