9 =+ For the reaction below AG° = + 33.0 kJ, AH° = + 92.2 kJ, and AS° =+ 198.7 J/K. Estimate the temperature at which this reaction occurs. 2 NH3(g) →N2(g) + 3H2(g) A) 0.464 K B) 166 K C) 298 K D) 464 K A B C

Thermodynamics provides a way to interpret everyday occurrences. If you live in northern climates, one common experience is that during early winter, snow falls but then melts when it hits the ground. Both the formation and the melting happen spontaneously. How can thermodynamics explain both of these seemingly opposed events?

When 7.11 g NH4NO3 is added to 100 mL water, the temperature of the calorimeter contents decreases from 22.1 C to 17.1 C. Assuming that the mixture has the same specific heat as water and a mass of 107 g, calculate the heat q. Is the dissolution of ammonium nitrate exothermic or endothermic?

For the reaction BaCO3(s) BaO(s) + CO2(g), rG = +219.7 kJ/mol-rxn. Using this value and other data available in Appendix L, calculate the value of fG for BaCO3(s).

Identify the following processes as either spontaneous or not spontaneous. (a) Ice melts when placed in a flask containing water at 5 C. (b) Hydrogen iodide molecules decompose at 400 K to give a mixture of H2, I2 and HI. (c) Ethanol and water are mixed to form a solution. (d) Slightly soluble PbCl2 (Ksp = 1.7 105) dissolves in water to form a saturated solution.

9.83 A student performing a calorimetry experiment combined 100.0 mL of 0.50 M HCl and 100.0 mL of 0.50 M NaOH in a coffee cup calorimeter. Both solutions were initially at 20.0°C, but when the two were mixed, the temperature rose to 23.2°C. (a) Suppose the experiment is repeated in the same calorimeter but this time using 200 mL of 0.50 M HCl and 200.0 mL of 0.50 M NaOH. Will the T observed he greater than, less than, or equal to that in the first experiment, and why? (b) Suppose that the experiment is repeated once again in the same calorimeter, this time using 100 mL of 1.00 M HCl and 100.0 mL of 1.00 M NaOH. Will the T observed he greater than, less than, or equal to that in the first experiment, and why?

2. In which of the following reactions is there a significant transfer of energy as work from the system to the surroundings? This occurs if there is a change in the number of moles of gases. C(s) + O2(g) → CO2(g) CH4(g) + 2 O2(g) → CO2g) + 2 H2O(g) 2 C(s) + O2(g) → 2 CO(g) 2 Mg(s) + O2(g) → 2 MgO(s)

Athletic trainers use instant ice packs that can be cooled quickly on demand. Squeezing the pact breaks an inner container, allowing two components to mix and react. This reaction makes the pack become cold. Describe the heat flow for this spontaneous process.

Given the following information at 25C, calculate G at 25C for the reaction 2A(g)+B(g)3C(g) Substance Hf(kJ/mol) S(J/molK) A(g) 191 244 B(g) 70.8 300 C(g) 197 164 a 956 kJ b 956 kJ c 346 kJ d 346 kJ e 1.03 103 kJ

Given the thermochemical expression CaO(s) + 3C(s) CaC2(s) + CO(g) rH = 464.8 kJ/mol calculate the quantity of energy transferred when (a) 34.8 mol CO(g) is formed by this reaction. (b) A metric ton (1000 kg) of CaC2(s) is manufactured. (c) 0.432 mol carbon reacts with CaO(s).