Passage V
A binary phase diagram (BPD) shows how the phases of a mixture of 2 chemicals vary with temperature and composition at 1 atmosphere (atm) of pressure. The phases include the solid (s) phase of each chemical and the liquid (I) solution phase of the 2 chemicals. The eutectic is the point where all 4 regions of the BPD intersect. It indicates the conditions at which all the phases represented in the 4 regions exist in equilibrium. When a mixture is at equilibrium, no net phase change occurs. Figure 1 is a BPD for durene and biphenyl. Figure 2 is a BPD for durene and naphthalene.
Figures adapted from Jurgen Gallus et al. , “Binary Solid-Liquid Phase Diagrams of Selected Organic Compounds."©2001 by Division of Chemical Education, Inc.,American Chemical Society.
27. Consider a durene-biphenyl mixture at 1 atm that is 40% durene by mass. According to Figure 1, solid durene, solid biphenyl, and a liquid solution will all be present in equilibrium at a temperature closest to which of the following?
Your Answer is
Correct Answer is A
Explanation
According to figure 1, when the abscissa is 40 and the ordinate is about 42 (that is, the intersection of several line segments), there will be three states of matter