1. Two reactions, A(g) = B(g) (reaction I) and C(g) = D(g) (reaction II), were studied at a fixed temperature and the following concentrations were measured once each system had reached equilibrium:

   Data for Reaction I____Data for Reaction II

   run	pA(atm)	pB(atm)		run	pC(atm)	pD(atm)
   1	0.100	0.150		5	100.0	74.4
   2	0.050	0.075		6	5.00	2.54
   3	0.300	0.450		7	25.0	13.6
   4	0.200	0.300		8	0.300	0.150

   • We have assumed ideal gas behavior in our treatment of chemical equilibrium. In which case do the data support the assumption of ideality. What is the value of the equilibrium constant in this case?
   • If a system does not demonstrate ideal gas behavior, what is the source of the non-ideality? Provide the best estimate of the equilibrium constant in this case.
   • Why was the temperature held constant?

2. In many cases a reaction can occur in stages and a detailed knowledge of chemical equilibrium is needed to optimize the yield of a particular product. Consider the following set of gas-phase fluorination reactions. This chemistry is important in discovering a substitute for freons.

   reaction 1: CH₄(g) + F₂(g) = CH₃F(g) + HF(g)
   reaction 2: CH₃F(g) + F₂(g) = CH₂F₂(g) + HF(g)
   reaction 3: CH₂F₂(g) + F₂(g) = CHF₃(g) + HF(g)
   reaction 4: CHF₃(g) + F₂(g) = CF₄(g) + HF(g)
   

   • Suppose that 0.50 atm of methane is mixed with 2.50 atm of fluorine. Set up but do not solve a system of equations which when solved would yield the equilbrium concentration of all 7 species.
   • Obtain from the equilibrium constants of reactions 1-4 an expression for the equilibrium constant of the overall reaction:
     CH₄(g) + 4 F₂(g) = CF₄(g) + 4 HF(g)
   • How could the reaction conditions be adjusted to maximize the yield of CH₃F and minimize the yield of the other fluorocarbons?

3. Consider the combustion of gaseous propane to produce gaseous carbon dioxide and water at a temperature where the equilibrium constant is 1.00 x 10⁶ atm:
   C₃H₈(g) + 5 O₂(g) = 3 CO₂(g) + 4 H₂O(g)
   • Air is 20 mol-% oxygen and 80 mol-% nitrogen. An air-fuel mixture is prepared in which the partial pressure of propane is 0.10 atm and the partial pressure of air is 0.90 atm. This mixture will yield a relatively cold, yellow flame. Why?
   • A second lean mixture is prepared in which the partial pressure of propane is 0.020 atm and the partial pressure of air is 0.980 atm. Calculate the equilibrium partial pressure of each species.

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last updated, 24 October 1996