Equilibrium and partial pressures

[suckerpunched]

Homework Statement

Sulfuryl chloride SO2Cl2 decomposes into SO2 and Cl2 when heated. The decomposition is endothermic. A sample of 3.509 grams is placed into an evacuated 1.00 liter bulb and the temp is raised to 375K.

When the system has come to equilibrium at 375K, the total pressure is fount to be 1.43 atm. Calculate the partial pressures of SO2, Cl2, and SO2Cl2 at equilibrium

Homework Equations

Tried using proportions because no equilibrium constant is given

total mass of 1 mol of each compound: 270.2g
molar mass of 1 mol SO2Cl2: 135.1
molar mass of 1 mol SO2: 64.1
molar mass of 1 mol Cl2: 71.0

1.43atm * part/270.2g= x pressure of part

The Attempt at a Solution

SO2Cl2=.715atm
Cl2=.376atm
SO2=.339atm

The thing is, we were given the hint that an initial, change, equilibrium table would be needed somewhere in the problem, the other parts being pressure before dissociation, finding the equilibrium constant (part c, this is part b) and finally the effect the temp going to 500K would have on the equilibrium constant

 

[cemar.]

okay I am pretty that if you were to take the grams of S02Cl2 and convert that into moles you could use PV=nRT to get the pressure.
Then make your ice chart and that will be the initial pressure of SO2Cl2. And the initial pressures for SO2 and Cl2 would be 0. The change for them would be -x x and x.
so for E you would end with initial pressure SO2Cl2-x x and x.
the problem gives you that the total pressure is 1.43atm so that's the sum of the equilibirum pressures of the ICE chart. You can solve for x and use that to find all the pressures.

 

[Blueshift5]

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my response would be that your approach using proportions is incorrect for this problem. The use of an initial, change, equilibrium table is necessary to properly solve this problem. The equilibrium constant can be found using the partial pressures of the reactants and products at equilibrium. The effect of temperature on the equilibrium constant can also be determined using this table. I would recommend reviewing your approach and using the correct equations and methodology for finding partial pressures and equilibrium constants in an equilibrium system.