Final Exam Solution

7 21306 205 89 jmolk 10 points 5 per major

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Unformatted text preview: points) ΔS° = ΔS°products -­‐ ΔS°reactants = 2*(188.7) – [2*(130.6) + (205)] = -­‐89 J/mol·∙K (10 points, -­‐5 per major mistake i.e. stoichiometry, order, math I could not follow) Yes, 3 moles of gas converting into 2 moles of gas is an overall decrease in possible degrees of freedom, so entropy is negative for the system. c) H2 and O2 are at their reference states, so what are their ΔH° values? Given ΔH°(H2O) = –241.8 kJ/mol, what is ΔH° for the reaction? Based on your answer, does this process absorb or release heat? (circle one) (5 points) ΔH° = ΔH°products -­‐ ΔH°reactants = 2*(-­‐242) – [2*(0) + (0)]= -­‐484 kJ/mol (10 points, -­‐5 per major mistake i.e. stoichiometry, incorrect ΔH for O2/N2, order, math I could not follow) This reaction releases a large amount of heat. d) Calculate ΔG° for the reaction. Is this reaction spontaneous at 298 K? Yes or No (5 points) ΔG° = ΔG°products -­‐ ΔG°reactants ΔG° = ΔH° -­‐ T·∙ΔS° = -­‐484 kJ/mol – (298K*-­‐0.089kJ/mol·∙K)...
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This test prep was uploaded on 04/03/2014 for the course CHEM 1b taught by Professor Heath,rees during the Spring '13 term at Caltech.

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