How to Calculate Total Pressure in a Chemical Equilibrium System?

[annastewert]

Homework Statement

Introduced into a 1.70 −L flask is 0.120 mol of PCl5(g); the flask is held at a temperature of 227∘C until equilibrium is established.
PCl5(g)⇌PCl3(g)+Cl2(g)

What is the total pressure of the gases in the flask at this point? [Hint: Use data from Appendix D in the textbook and appropriate relationships from this chapter.]

Homework Equations

From the data tables I got ΔG for the following to be:
Cl2 = 0
PCl3 = -267.8
PCl5 = -305
From this I know ΔG to be 37.2.

ΔG=-RTln(K) (1)
PV=nRT (2)

The Attempt at a Solution

Using equation (1) I found K and then found the moles of each substance at equilibrium. I added these together and put them into equation (2) to get P. This isn't working for me. Is there a better way to do it?

 

[Chestermiller]

Homework Statement

Introduced into a 1.70 −L flask is 0.120 mol of PCl5(g); the flask is held at a temperature of 227∘C until equilibrium is established.
PCl5(g)⇌PCl3(g)+Cl2(g)

What is the total pressure of the gases in the flask at this point? [Hint: Use data from Appendix D in the textbook and appropriate relationships from this chapter.]

Homework Equations

From the data tables I got ΔG for the following to be:
Cl2 = 0
PCl3 = -267.8
PCl5 = -305
From this I know ΔG to be 37.2.

ΔG=-RTln(K) (1)
PV=nRT (2)

The Attempt at a Solution

Using equation (1) I found K and then found the moles of each substance at equilibrium. I added these together and put them into equation (2) to get P. This isn't working for me. Is there a better way to do it?

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