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Unformatted text preview: ChEn 2001, Homework #9 Due Monday, December 7, 2009 Problem 1. We want to figure out the error involved in using constant heat capacities relative to the temperature dependent fit, using acetylene as an example. Compute the H value for heating 1 mole of acetylene from 25 C to final temperatures up to 2000 C in 25 C increments (i.e. from 25 C to 50 C, from 25 C to 75 C, etc.). We will define the relative error as E= |H1 - H2 | H1 (1) where H1 is the value obtained with the temperature dependent coefficients and H2 is the value obtained with a constant coefficient. Plot the error as a function of temperature. Problem 2. Compute H and U for taking 1 mole of water from 80 C and 1 bar to 225 C and 7 bar using (i) model equations with a constant heat capacity, (ii) model equations with a temperature dependent heat capacity, and (iii) the steam tables using interpolation. Problem 3. Compute the enthalpy of combustion for glyoxal (C2 H2 O2). Cite your source for the heat of formation of glyoxal. Problem 4. Compute the heat of reaction for the partial combustion of 3 moles of ethylacetate to form carbon monoxide and water at 125 C and 0.5 bar. 1 ...
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- Fall '08