Question

Lexan is a plastic used to make compact discs, eyeglass lenses, and bullet-proof glass. One of the compounds used to make Lexan is phosgene (COCl2), an extremely poisonous gas. Phosgene decomposes by the following reaction for which Kp = 6.8 ✕ 10-9 at 100°C. COCl2(g) equilibrium reaction arrow CO(g) + Cl2(g) If pure phosgene at an initial pressure of 2.0 atm decomposes, calculate the equilibrium pressures of all species.

Answer 1

`p_(CO)=1.41atm\\p_(Cl_2)=1.41atm\\p_(COCl2)=0.59atm`

Step-by-step explanation:

Hello,

In this case, since the undergoing chemical reaction is:

`Kp=(p_(CO)^(eq)p_(Cl_2)^(eq))/(p_(COCl_2)^(eq))`

Thus, if we introduce the changing pressure,
`x`, the law of mass action becomes:

`Kp=((x)(x))/((2.0atm-x))`

Now, by taking the given value of Kp we solve for x as follows:

`(2.00atm-x)Kp=x^2\\x^2+Kp*x-2.00atm=0\\x^2+6.8x10^(-9)-2=0\\x_1=1.41atm\\x_2=-1.41atm`

therefore, the result is 1.41 atm so the equilibrium pressures turn out:

`p_(CO)=1.41atm\\p_(Cl_2)=1.41atm\\p_(COCl2)=2.00-1.41=0.59atm`

Best regards.