A chemist stores 10.0 g of ethanol in three sealed
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A chemist stores 10.0 g of ethanol in three sealed, rigid containers maintained respectively at –120 °C, 25 °C, and 80 °C. At –120 °C the ethanol is a crystalline solid, at 25 °C it is a liquid, and at 80 °C it exists as a vapor at 1.00 atm.
Assume no chemical decomposition occurs and that the mass of ethanol remains 10.0 g in each container.
(a) Describe qualitatively how the average spacing between ethanol molecules differs among the three containers.
(b) Rank the ethanol samples in order of decreasing mass density (largest to smallest). Justify your ranking in terms of molecular spacing.
(c) Rank the three samples in order of increasing ease of compression (least pressure required to achieve a given fractional volume decrease). Explain your reasoning.
(d) For each phase, discuss how the effective strength of intermolecular forces influences both the density and the compressibility you ranked above.