For 2SO2(g)+O2(g)⇌2SO3(g),

Kp=3.0×104 at 700 K. In a 2.00-L vessel the equilibrium mixture contains 1.15 g of SO3 and 0.107 g of O2.

1) How many grams of SO2 are in the vessel?

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A flask is charged with 1.500 atm of N2O4(g) and 1.00 atm NO2(g) at 25 ∘C, and the following equilibrium is achieved:
N2O4(g)⇌2NO2
After equilibrium is reached, the partial pressure of NO2 is 0.519 atm .

2) Calculate Kc for the reaction.

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3) Phosphorus trichloride gas and chlorine gas react to form phosphorus pentachloride gas:
PCl3(g)+Cl2(g)⇌PCl5(g).
A 7.5-L gas vessel is charged with a mixture of PCl3(g) and Cl2(g), which is allowed to equilibrate at 450 K. At equilibrium the partial pressures of the three gases are PPCl3 = 0.128 atm , PCl2 = 0.159 atm , and PPCl5 = 1.90 atm .

Calculate Kc for this reaction at 450 K.

4 answers

A flask is charged with 1.500 atm of N2O4(g) and 1.00 atm NO2(g) at 25 ∘C, and the following equilibrium is achieved:
N2O4(g)⇌2NO2
After equilibrium is reached, the partial pressure of NO2 is 0.519 atm . Calculate Kc.

........N2O4 ⇌ 2NO2
I.......1.5.....1.0
C.......+p......-2p
E......1.5+p....1.0-2p

You know 1.0-2p = 0.519. Solve for p. KNowing p you calculate pN2O4 at equilibrium. Write Kp expression, substitute the equilibrium values and solve for Kp. Convert to Kc using Kp = Kc(RT)^delta n.
Post your work if you get stuck.
It appers to me that the easy way is to solve for Kp since partial pressure of each gas is given at equilibrium, then convert to Kc.

If you want to do it the longer way, use PV = nRT and solve for n for each gas, then convert to M using M = mols/L. Then plug into the Kc expression and solve for Kc
Post your work if you get stuck.
Here is #1,
For 2SO2(g)+O2(g)⇌2SO3(g),
Kp=3.0×104 at 700 K. In a 2.00-L vessel the equilibrium mixture contains 1.15 g of SO3 and 0.107 g of O2.

Use PV - nRT and calculate pSO3.
Use PV = nRT and calculate pO2
Write the Kp expression, substitute the partial pressures of SO3 and O2 and calculate pSO2. Then use PV = nRT and solve for mols SO2 and convert to grams SO2. Post your work if you get stuck.
I've worked this problem several times and keep getting the wrong answer. I've got .035, .0255, and 51.04. Are any of these close?