Passage V
When a mixture is at equilibrium, no net phase changes occur. Figure 1 shows the phases of the metals gold (Au )and thallium (TI) present in various Au-TI mixtures at different temperatures and at equilibrium. The Au-TI mixtures contain only Au and Tl, so an Au-TI mixture that contains 60% Au will contain 40% Tl, and 100 g of this mixture will contain 60 g of Au and 40 g of Tl.
A cooling curve shows how the phases of the metals in the mixture change as it cools over time. Figure 2 shows a cooling curve for an Au-TI mixture containing 58% Au. Figure 2 also explains how Figure 1 is related to Figure 2.
26. According to Figure 2, which of the following best describes what occurs as an Au-TI mixture containing 58% Au at 900°C is cooled to 0°C in 1 hr? During the 1 hr, the temperature of the mixture will:
Your Answer is
Correct Answer is H
Explanation
Look at figure 2, the temperature drops first when dropping from 900°C to 0°C, and then stays constant for a while at 120°C, and then drops again