Chapter 12, Problem 23P

Consider a mixture of air and gasoline vapor in a cylinder with a piston. The original volume is 40. cm3. If the combustion of this mixture releases 950. J of energy, to what volume will the gases expand against a constant pressure of 650. torr if all the energy of combustion is converted into work to push back the piston?

In the equation w = P V, why is there a negative sign?

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?

Determine an expression for V/T p, n in terms of and . Does the sign on the expression make sense in terms of what you know happens to volume as temperature changes?

Would the amount of heat absorbed by the dissolution in Example 5.6 appear greater, lesser, or remain the same if the heat capacity of the calorimeter were taken into account? Explain your answer.

Consider a sample containing 5.00 moles of a monatomic ideal gas that is taken from state A to state B by the following two pathways: For each step, assume that the external pressure is constant and equals the final pressure of the gas for that step. Calculate q, w, E and H for each step in kJ, and calculate overall values for each pathway. Explain how the overall values for the two pathways illustrate that E and H are state functions, whereas q and w are path functions. Hint: In a more rigorous study of thermochemistry, it can be shown that for an ideal gas: E=nCvTand H=nCpT where Cv is the molar heat capacity at constant volume and Cp is the molar heat capacity at constant pressure. In addition, for a monatomic ideal gas, Cv=32R andCp=52R , where R = 8.3145 J/K mol.

For the process H2O(l)H2O(g) at 298 K and 1.0 atm, H is more positive than E by 2.5 kJ/mol. What does the 2.5 kJ/mol quantity represent?

Consider 2.00 moles of an ideal gas that are taken from state A (PA = 2.00 atm, vA = 10.0 L) to state B (PB = 1.00 attn, VB = 30.0 L) by two different pathways: These pathways are summarized on the following graph of P versus V: Calculate the work (in units of J) associated with the two pathways. Is work a state function? Explain.

A piece of zinc of mass 5.0 g is placed in a beaker of dilute hydrochloric acid. It undergoesthe reaction Zn + 2 H+ Zn + H2. Assuming that the volume of the reactant is negligible compared to the volume of the gas and that the gas is perfect, calculate the work done by the system as a result of the reaction. The atmospheric pressure is 1.1 atm and the temperature 23 °C.