ThermodynamicsIV

# ThermodynamicsIV - THERMODYNAMICS III Q1. a) 1999 General...

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THERMODYNAMICS III Q1. 1999 General Physical Chemistry I, Q5 a) Derive the Clapeyron equation for the temperature dependence of the pressure at which two phases are in equilibrium. You may use without proof the relationship dG = Vdp – SdT, in which the symbols have t h e i r u s u a l m e a n i n g s . [ 3 ] b) Develop the result in a) for the case in which one of the phases is gaseous, to establish the Clausius- Clapeyron equation. Identify any assumptions you make. [3] c) Many of the higher mountains in the world have altitudes in excess of 25000 feet above sea level. At these altitudes the atmospheric pressure is around 250 Torr. Calculate the changes in i) the freezing point; and ii) the boiling point of water at this pressure relative to normal conditions, given the following data density of ice = 0.92 g cm- 3 density of water = 1.00 g cm -3 enthalpy of fusion of ice = 6.01 kJ mol -1 enthalpy of vapourisation of water at the normal boiling point = 40.7 kJ mol -1 normal freezing point of water = 273.15 K 1 bar = 760 Torr relative atomic masses: O = 16, H = 1. [8] d) The single-component phase diagrams shown below relate to the following substances: water, carbon dioxide, and carbon. Identify which diagram relates to which substance and label all phases shown. [6] Q2. 1998 General Physical Chemistry II, Q1 a) Define the quantities enthalpy (H), and Gibbs Free Energy (G) and explain why they are widely used in c h e m i s t r y [ 4 ] b)

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## This note was uploaded on 05/09/2010 for the course CHE 3051 taught by Professor Sitimachmud during the Spring '08 term at National Central University.

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ThermodynamicsIV - THERMODYNAMICS III Q1. a) 1999 General...

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