The heat of vaporization, delta Hvap of carbon tetrachloride, CCl4, at 25 degree
ID: 782716 • Letter: T
Question
The heat of vaporization, delta Hvap of carbon tetrachloride, CCl4, at 25 degree C is 43.0 kJ/mol. If 1 mol of liquid CCl4 has an entropy of 214 J/K, what is the entropy of 1 mol of the vapor at this temperature? Calculate the change in entropy, delta S degree, at 25 degree C for the reaction in which urea is formed from NH3 and CO2 The standard entropy of NH2CONH2 is 174 J/(mol.K). See Table 19.1 for other values. 2NH3 (g) + C02 (g) rightarrow NH2CONH2(aq) + H2O(I) What is the standard free energy change, delta G degree, for the following reaction at 25 degree C? Use values of delta Hf degree and S degree, from Appendix L N2(g) + 3H2(g) rightarrow 2NH3(g) Calculate delta G degree for the combustion of 1 mol of ethanol, C2H5OH, at 25 degree C. Use the standard free energies of formation given in Appendix L. C2H5OH (I) + 3O2 (g) rightarrow 2CO(g) +3H2O(g) Find the value for the equilibrium constant, K, at 25 degree C (298 K) for the following reaction. The standard free-energy change, delta G , at 25 degree C equals -13.6 kJ. 2NH3(g)+CO2(g) rightarrow NH2CONH2(aq) + H2O(l) Find the delta G degree for the following reaction at 25 degree C and l000 degree C. Relate this to reaction spontaneity. CaCO3 (s) rightarrow CaO(s) + CO2 (g)Explanation / Answer
9)
Heat of formation of CO2 (g) = -393.509 kJ/mol
Heat of formation of H2O (l) = -285.83 kJ/mol
Total enthalpy change = total heat of formation of CO2 reaction + total heat of formation of H2O in reaction
Therefore, total enthalpy change = 2(-393.509) + 3(-285.83) = -787.018 + (-857.49)
= -1644.508 kJ/mol
similarly total entropy change = (2*213.6 + 3*188.7) - (161 + 3*205) =217 J/mol.K = 0.217 kJ/mol.K
delta G = delta H - T* delta S = -1644.508 - 298*0.217 = 1709.174 kJ
10)
dG = -13.6 kJ
dG = - RT lnK
-13.6 kJ = - (0.008314) (298) lnK
lnK = 5.489
K = 242
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