From the following data, determine A, He for diborane, B2H6(g), at 298 K: (1) B2H6(g) +3 O2 (g)→ B2O3(s) + 3 H₂O(g) A₂H = -1941 kJ mol‍¹ (2) 2 B(s) + 3/2 O2(g) → B2O3(S) (3) H2(g) + 1/2 O2(g) → H₂O(g) AH =-2368 kJ mol-1 НӨ A₂H = -241.8 kJ mol‍¹

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).

An industrial process for manufacturing sulfuric acid, H2SO4, uses hydrogen sulfide, H2S, from the purification of natural gas. In the first step of this process, the hydrogen sulfide is burned to obtain sulfur dioxide, SO2. 2H2S(g)+3O2(g)2H2O(l)+2SO2(g);H=1124kJ The density of sulfur dioxide at 25C and 1.00 atm is 2.62 g/L, and the molar heat capacity is 30.2 J/(mol C). (a) How much heat would be evolved in producing 1.00 L of SO2 at 25C and 1.00 atm? (b) Suppose heat from this reaction is used to heat 1.00 L of the SO2 from 25C to 500C for its use in the next step of the process. What percentage of the heat evolved is required for this?

A volume of 1.50 L of argon gas is confined in a cylinder with a movable piston under a constant pressure of 1.22 105 Pa. When 1.25 kJ of energy in the form of heat is transferred from the surroundings to the gas, the internal energy of the gas increases by 1.11 kJ. What is the final volume of argon gas in the cylinder?

When vapors from hydrochloric acid and aqueous ammonia come in contact, they react, producing a white cloud of solid NH4C1 (Figure 18.9). HCI(g) + NH3(g) NH4Cl(s) Defining the reactants and products as the system under study: (a) Predict whether S(system), S(surroundings), S(universe), rH, and rG (at 298 K) are greater than zero, equal to zero, or less than zero; and explain your prediction. Verify your predictions by calculating values for each of these quantities. (b) Calculate the value of Kp for this reaction at 298 K.

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).

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?

Calculate the standard Gibbs free-energy change when SO3 forms from SO2 and O2 at 298 K. Why is sulfur trioxide an important substance to study? (Hint: What happens when it combines with water?)

The decomposition of ozone, O3, to oxygen, O2, is an exothermic reaction. What is the sign of q? If you were to touch a flask in which ozone is decomposing to oxygen, would you expect the flask to feel warm or cool?

9.42 Why is enthalpy generally more useful than internal energy in the thermodynamics of real world systems?