142 worked out problems

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Chapter 15

a. The decomposition of PCl5 occurs via the reaction

PCl5(g) <--> PCl3(g) + Cl2(g)

A sample of PCl5 is placed in a reaction vessel held at 250 °C at an initial pressure of 1.10 atm. When equilibrium is attained, the pressure of PCl5 is 0.33 atm. Calculate Kp for this reaction. [1.77] solution

b. Suppose that H2(g) and CH4(g) are brought into contact with C(s) at 500 °C with PH2= 0.20 atm and PCH4 = 3.0 atm. Is the reaction

C(s) + 2H2(g)<--> CH4(g)   Kp 2.69 x 103
at equilibrium? If not, which direction will the reaction proceed towards equilibrium? What is the equilibrium pressures of each? [H2 = 0.036 atm, CH4 = 3.082 atm]
solution

c.
An unknown mass of NH4Cl(s) is placed in an evacuated container and allowed to come to equilibrium at 500K:
1 NH4Cl(s) <-->1 NH3(g) + 1 HCl(g)
At equilibrium, the total pressure is 6.2 atm. What is the value of Kp for this equilibrium? [9.61] solution

d.
NH4Cl(s) <-->1 NH3(g) + 1 HCl(g)
A flask is filled with 3.2 atm of NH3(g) and 1.5 atm of HCl(g) at 300 K. Once equilbrium is achieved, Ptotal = 2.50 atm. Calculate Kp for this reaction. [0.84] solution

e.
At 500 K, the following equilibrium exists, with a Kc = 1.0 x 102
1 H2(g) + 1 F2(g) <--> 2 HF (g)
In a particular experiment, 3.0 mol of F2(g) and 3.0 mol of H2(g) are added to a 2.0 L flask. Calculate the equilibrium concentration of each species.[HF = 2.50 M, F2 = 0.25 M, H2 = 0.25 M] solution

~MEO 23 Feb 06