For the following reaction at 600. K, the equilibrium constant, Kp, is 11.5.

Question

PCl5(g) equilibrium reaction arrow PCl3(g) + Cl2(g)

Suppose that 2.030 g of PCl5 is placed in an evacuated 535 mL bulb, which is then heated to 600. K.
(a) What would be the pressure of PCl5 if it did not dissociate?
(b) What is the partial pressure of PCl5 at equilibrium?
(c) What is the total pressure in the bulb at equilibrium?
(d) What is the degree of dissociation of PCl5 at equilibrium?

PLEASE HELP

Answer 1

a. 1.263 IF the unit is atmospheres.
Here's the rest of the answers too :)
b. Set up at ICE chart.
Initial: pressure PCl5 = 1.263 atm
partial p PCl3 = 0
partial p Cl2 = 0

change: partial p PCl3 = +y
partial p Cl2 = y
partial pressure PCl5 = -y

equilibrium pressures:
add the columns to obtain
partial p PCl3 = y
partial p Cl2 = y
partial pressure PCl5 = 1.263-y

Now plug all that into the equilibrium constant expression; Kp = ------
and solve for y, the only unknown in the equation. I expect you will get a quadratic equation. That will give you y and 1.263-y (1.263-y will be the partial pressure of PCl5).

c. Add partial pressure PCl5 + partial pressure PCl3 + partial pressure Cl2.

d. The degree of dissociation is
partial p PCl5 at equilibrium/partial p PCl5 initially. By the way, if you then multiply that by 100 you will have percent dissociation. The degree of dissociation IS NOT expressed in percent terms.

Answer 2

a. USE PV = nRT. Let's just say P is 1 atm. It isn't but let's go with that.
b. PCl5 ==> PCl3 + Cl2
I.......1 atm.......0........0
C.......-p...........p.........p
E.....1-p...........p..........p
Then Kp = 11.5 = (p)(p)/(1-p)
Solve for p and evalute 1-p

c. Ptotal = p(PCl5) + p(PCl3) + p(Cl2) = ?
d. degree of dissociation = [p(PCl3)/p(PCl5)]

Post your work if you get stuck.

Answer 3

NOTE: Answers given by HONEY. Check that 1.263 carefully. I obtained a different answer.
Also the ICE chart is not set up properly; i.e., equilibrium p for PCl5 is 1.263-y but the 1.263 value is in question.
For d the degree of dissociation is a typo; i.e., the first PCl5 should be PCl3

Answer 4

My apologies, thanks for clarifying