Calculate the value of S° for the reaction shown: 2 NH3(g)  N2(g) + 3 H2(g) At 25°C the values of entropy in J K−1 mol−1 are ammonia, 192.77; nitrogen, 191.61; and hydrogen, 130.68.

For a particular reaction, AH° = 67.7 kJ and AS° = 126.9 J/K. Assuming these values change very little with temperature, at what temperature does the reaction change from nonspontaneous to spontaneous? T = K Is the reaction in the forward direction spontaneous at temperatures greater than or less than the calculated temperature? less than greater than

What is the temperature range in which the following reaction is spontaneous? N₂+ 3H2 → 2NH3 S N2(g) 191.5 J/mol K S H2(g) 130.6 J/mol K S NH3(g) 192.5 J/mol K AH, N2(g) 0 kJ/mol AH, H2(g) 0 kJ/mol AH, NH3(g) -46.19 kJ/mol

The heat of vaporization of carbon disulfide, CS2, at 25°C is 27.2 kJ/mol. What is the entropy change when 1.60 mol of vapor in equilibrium with liquid condenses to liquid at 25°C? The entropy of this vapor at 25°C is 243 J/(mol.K). Entropy change J/K = What is the entropy of the liquid at this temperature? Entropy J/K =

Without consulting the tables, what sign do you expect for the change in entropy (delta S) for the following reaction? 2 C4H10 (g)  +  13 O2 (g)   →    8 CO2 (g)  +  10 H2O (g)  a. none of these b. negative c. can not be determined (too close to estimate) d. positive

Using enthalpies of formation, calculate deltaH for the following reaction at 25°C. Also calculate deltaS for this reaction from standard entropies at 25°C. Use these values to calculate deltaG for the reaction at this temperature. Species  deltaHf(kJ/mol)  S(J/mol⋅K) CH3OH(l) –238.7 126.8 O2(g) 0 205.0 CO2(g) –393.5 213.7 H2O(l) –285.8 69.95 2CH3OH(l) +3O2(g) --- 2CO2(g) + 4H2O(l) deltaH =  kJ deltaS =  J/K deltaG =  kJ

Calculate ΔS when 25.0 g ethanol at 50.0 °C is added to 75.0 g ethanol at 10.0 °C in an insulated container where Cp = 111.5 J/mol K. Calculate the change in entropy of each ethanol sample, and then the total entropy change. Comment on what is happening to each sample, and overall. (answers: warm = -6.11 J/K; cold = +5.69 J/K; total = 0.42 J/K)

Given the following reaction and its enthalpy change, and the sign of the entropy change that you get using what you know of trends in entropy, S, when is this reaction spontaneous?           2 ClO2 (g)   +  2 TiCl4 (l)    →     2 TiO2 (s)   +   5 Cl2 (g)         Delta H =  – 343.8 kJ  Select one: a. This reaction is spontaneous at lower temperatures, but not at higher temperatures. b. This reaction is spontaneous at higher temperatures, but not at lower temperatures. c. This reaction is never spontaneous. d. none of these e. This reaction is spontaneous at all temperatures.

A chemical engineer is studying the two reactions shown in the table below. In each case, he fills a reaction vessel with some mixture of the reactants and products at a constant temperature of 63.0 °C and constant total pressure. Then, he measures the reaction enthalpy AH and reaction entropy AS of the first reaction, and the reaction enthalpy AH and reaction free energy AG of the second reaction. The results of his measurements are shown in the table. Complete the table. That is, calculate AG for the first reaction and AS for the second. (Round your answer to zero decimal places.) Then, decide whether, under the conditions the engineer has set up, the reaction is spontaneous, the reverse reaction is spontaneous, or neither forward nor reverse reaction is spontaneous because the system is at equilibrium.

Use the data to calculate the standard entropy change for the following reaction: 5. S°[Mt(s)] 43.2 J/K mol Mt(s) + ½ O2(g) → MtO(s) S°[O2(g)] = 305.1 J/K-mol S°[MtO(s)] 62.6 J/K mol a) -133.2 J/K b) -285.7 J/K c) 285.7 J/K d) 133.2 J/K