Thermodynamics and an Introduction to Thermostatistics 7, Exercises of Chemistry

Download Thermodynamics and an Introduction to Thermostatistics 7 and more Exercises Chemistry in PDF only on Docsity! Fall Problem Set 7 3.20 MIT 2001Fall 2002 LEVEL 1 PROBLEMS Problem 1.1 The properties of mixing for a liquid A-B mixtures at a temperature of 1000 K are show below. (a) Is the liquid A-B mixture an ideal solution? Briefly justify your answer. (b) What is the vapor pressure of A in a mixture with 95% B? .(c) 1 mole of pure A liquid at 1000K is added to 1 5 moles of pure B liquid at 1000K. How much heat needs to be extracted/added to keep the system at 1000K ? Data: �5Vapor pressure of pure A at 1000K = 10 atm �2Vapor pressure of pure B at 1000K = 10 atm JHeat capacity for all compositions of the liquid = 30 mol�K 1 Problem 1.2 At low temperatures Fe-75% Ni forms an ordered compound (structure is given below). This compound is ferromagnetic. From the third law of thermodynamics we know that the entropy of this compound at 0K can be set equal to 0. Discuss the different microscopic mechanisms that contribute to the increase in entropy as the material is heated from 0K. Give specific microscopic mechanisms and explain how they contribute to the entropy. Problem 1.3 Si and Ge form ideal solutions in both the solid and liquid state. The melting point of Si is 938C . The melting point of Ge is 1414C. When I add a small amount of Ge to Si the melting point of the solution will be greater or less than 938C. Problem 1.4 In the free energy diagram below, graphically indicate the free energy of mixing at x  when a solid and a liquid compete for stability. 2