How Do I Calculate Equilibrium Constants for Chemical Reactions?

[xoilovemeryl]

Okay so I have a big packet to do and I figured all of them out but 3. If anyone could help me with any of them, I'd greatly appreciate it!

1. Find KC for this reaction: C6H4 (g) + F2 (g) makes 2CF4 (g) + 4HF(g)

Given: H2(g) + F2(g) makes 2HF (g) Kc= 1.4x1014
1/2C(s) + F2 makes 1/2CF4(g) Kc= 2.0x108
2C(s) + 2H2(g) makes C2H4(g) Kc=1.7x10-2

2. NH4Co2NH2(s) makes 2NH3(g) + CO2(g)

Starting with only the solid, it is found that at 40 degrees C the total gas pressure (NH3 and CO2 is 0.363 atm. Calculate the equilibrium constant, Kp

3. A container is filled with NOBr to 0.762 atm and 65.1% of it decomposes. Determine Kp for this reaction: 2NOBr(g) makes 2NO(g) + Br2 (g)

I have been trying to figure these out for 3 days and just can't. I've tried using the ICE chart with y but that didn't work. If anyone could just tell me what to do (I'm not even looking for an answer, just steps) that would be so amazing. Thanks for your time!

Ok for the first one I tried adding up all of the K_c's but that just seems to easy. I also tried to manipulate each equation to make it like the first one, but that didn't work either.

For the second one, I thought of putting the 0.363 with the NH₄CO₂NH₂ using the ICE chart but that doesn't seem right, although it may be.

And for the final one could I put .763 with the 2NOBr and use Y in the ICE chart to find 2NO and Br₂?

Thanks :)

 

[Nino MMP]

1. For the first question, you need to use the Reaction Quotient (Q) equation to find Kc. Q is equal to the product of the concentrations of the products over the product of the concentrations of the reactants. You can then plug in the values of each concentration to solve for Kc.2. For the second question, you can use the Ideal Gas Law to calculate the value of Kp. The Ideal Gas Law states that PV=nRT where P is the pressure, V is volume, n is the number of moles of gas, R is the ideal gas constant, and T is temperature. Thus, you can rearrange the equation to solve for Kp.3. For the third question, you can also use the Ideal Gas Law to calculate the value of Kp. Here, you need to convert the partial pressure of 0.762 atm into the total pressure and then use the equation above to solve for Kp.