Thermodynamics and an Introduction to Thermostatistics 3, Exercises of Chemistry

Download Thermodynamics and an Introduction to Thermostatistics 3 and more Exercises Chemistry in PDF only on Docsity! Fall 2001 Problem Set 3 3.20 MIT Professor Gerbrand Ceder Problem 1 Fall 2003 It is found that a certain liquid boils at a temperature of 95 C at the top of a hill, whereas it boils at a temperature of 105 C at the bottom. The latent heat is 1000 cal/mol. What is the approximate height of the hill? Problem 2 The boiling point of Li is 1620 K. (a) What is the vapor pressure of liquid Li at 1000 K? (b) Estimate the melting point of lithium from the data given. Data: Enthalpy of evaporation is 156 kJ/mol Vapor pressure above solid Li is given by: ,19 314 ln( P ) = 13 049
. T Problem 3 (a) A chamber at 1500K with a volume of one cubic meter contains one gram of Ag. What is the status of the silver in the chamber? Is it all vapor, all liquid, or part liquid and part vapor? If the latter, what fraction of the silver is in the vapor phase? (b) How much heat is required to evaporate one mole of Ag from a very large quantity of a silver-copper liquid .solution at 1500 K containing xAg = 0 25 . Assume the solution is ideal. Data for Silver: Melting point = 1235 K Vapor pressure of liquid given by 30671 .ln( P ) =
+ 12 5 [P in atm, T in K] T Enthalpy of melting for Ag = 11.3 kJ/mol Heat capacity for liquid Ag = 33 J/mol-K Problem 4 A container kept at a constant temperature of 70 C (see figure) contains a small amount of liquid water. The total gas pressure in the container is 1 atm. This gas phase consists of the water vapor in equilibrium with the liquid water and inert N 2 gas. What is the total pressure in the container when the volume of the container is isothermally reduced to half of the original volume? You may assume that the liquid water takes up a negligeable amount of volume. Also, you may neglect the effect of total pressure on the vapor pressure of water. Data: Enthalpy of evaporation for water at 40 C is 43.54 kJ/mol Vapor pressure of water at 70 C is 0.3 atm 1 Problem 5 (a) What is the vapor pressure of H O at 100 C (the boiling point of water) ? 2 (b) The weather forecast tells me that it is 59 F (15C) outside with a relative humidity of 65%. What is the dew point of that air? Data: Enthalpy of evaporation for H O at 100 C = 40.6 kJ/mol 2 Problem 6 the unit cell of the material. What is the partial molar volume of Li in this material for x = 1? Look carefully at what exactly this graph gives you! Below is the volume of the unit cell of Li NiO2 as a function of x. When x increases Li is accommodated inside x Problem 7 The vapor pressure of pure B at 1000 K is 5  10 �4 atm. If B is in an ideal solution with another species at 1000 K, its vapor pressure will be: �4Higher than 5  10 �4Lower than 5  10 �4Equal to 5  Impossible to say 10 2