1. The gases SO2, O2 and SO3 are allowed to reach equilibrium at a constant temperature. The equilibrium constant for the reaction
2SO2(g) + O2(g) -> 2S03(g)
is 1.6 x 104 atm-1

a) Calculate the value of Kp for the reaction
SO2(g) + ½O2(g) -> SO3(g)

(b) The equilibrium constant for the dissociation of Pcl5(g) to form PCl3(g) and Cl2(g) is
0.04 at 250°C. An equilibrium mixture contains 0.20 mol PC13 and 0.12 mol Cl, in a
4000 cm container.
i) Write the chemical equation.
ii) Calculate the concentration of PCIs in this container.

a) In this case, since we can see that the second reaction is equal to the half of the first reaction, we can relate the equilibrium constants as shown below:

[tex]K_2=K_1^{1/2}[/tex]

Thus, by plugging in the the equilibrium constant of the first reaction we obtain:

[tex]K_2=(1.6x10^4atm^{-1})^{1/2}\\\\K_2=1.3x10^{2}atm^{-1/2}[/tex]

b) In this case, for the described reaction we can write:

[tex]PCl_5\rightarrow PCl_3+Cl_2[/tex]

Thus, the corresponding equilibrium expression is:

[tex]K=\frac{[PCl_3][Cl_2]}{[PCl_5]}[/tex]

In such a way, since we know the equilibrium constant and the concentrations of PCl3 and Cl2 at equilibrium, we can compute the concentration of PCl5 at equilibrium as follows:

[tex][PCl_5]=\frac{[PCl_3][Cl_2]}{K}\\[/tex]

[tex][PCl_5]=\frac{\frac{0.20mol}{4L} *\frac{0.12mol}{4L} }{0.04}[/tex]

[tex][PCl_5]=0.0375M[/tex]

Best regards!