The equilibrium system N2O4(g) = 2NO2(g) was established in a 1.00 liter vessel. Upon analysis the following information was found: [NO2] = 0.50 M; [N2O4] = 0.025 M. What is the value of Keq


I don't know how to do these at all. My computer did one example but I didn't understand it. Can someone show me step by step so I can fig the rest out on my own.

Refer to the definition of Keq.

For a general reaction

w A + x B = y C + z D

where w, x, y, and z are the numeric coefficients and A, B, C, and D are the reactants and products, the following is the definition of Keq:



(I have no idea why the "B" came out in lower case) where the numbers in square brackers, [], indicate concentrations. If any of the items don't exist (no B, no D), those entries are simply eliminated from the equation. If additional entries exist, they are added -- the reactants on the top, the products on the bottom.

From this equation, you should be able to solve the problem with ease.

Is there a difference in kinding K eq and just finding K?

I figured out the answer to the question I asked it was 10 but another problem asked me to find just K is there a different route to take?

Quote:

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Originally Posted by SlyPhoenix

Is there a difference in kinding K eq and just finding K?

I figured out the answer to the question I asked it was 10 but another problem asked me to find just K is there a different route to take?

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I can't really answer the question because I don't know the context. My guess is that the "K" that is referred to is, in fact, Keq. There are other equilibrium constants: Ksp, Ka, Kb, (solubility product, acid, and base constants) for example. They're all calculated in similar ways. In the case of Ksp, the concentration of the solid is assumed to be constant so it's not factored into the equation.

For the reactions system 2H2(g) + S2(g) 2H2S(g), a 1.00 liter vessel is found to contain 0.50 moles of H2, 0.020 moles of S2, and 68.5 moles of H2S. Calculate the numerical value of the Keq of this system. (format: 3.4e4 = 3.4 x 104)


well there is the question and I set it up just like you would do a Keq formula and the first time I got 0.08 but it says the answer should be 9.something and I don't know how they got it.

I did Keq= [H2]^2/ [H2]^2 + [S2]

is that right?

If this is the correct reaction (I think it is)



then this is the equation:



Using your values, it appears that the answer is 1.066e-6, if I've done everything correctly.

O okay I did it reversed I had the product on top I believe.

I did, too, the first time I wrote it down.

Hmm I got the same thing you did so I submitted the answer and I said it was 9.4e5 so I don't know what we did wrong.

I have another question.
The compound PCl5 decomposes into Cl2 and PCl3. The equilibrium of PCl5(g) Cl2(g) + PCl3(g) has a Keq of
2.24 x 10-2 at 327o C. What is the equilibrium concentration of Cl2 in a 1.00 liter vessel containing 0.235 mole of PCl5 and 0.174 mole of PCl3?

what's the formular for that because they already gave Keq or do I use that formula ans work backwards?

Quote:

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Originally Posted by SlyPhoenix

Hmm i got the same thing you did so i submitted the answer and i said it was 9.4e5 so i dunno what we did wrong.

I have another question.
The compound PCl5 decomposes into Cl2 and PCl3. The equilibrium of PCl5(g) Cl2(g) + PCl3(g) has a Keq of
2.24 x 10-2 at 327o C. What is the equilibrium concentration of Cl2 in a 1.00 liter vessel containing 0.235 mole of PCl5 and 0.174 mole of PCl3?

whats the formular for that because they already gave Keq or do i use that formula ans work backwards?

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The procedure should be the same. Given a general reaction

w A + x B = y C + z D

where w, x, y, and z are the numeric coefficients and A, B, C, and D are the reactants and products, the following is the definition of Keq:



I'm not sure what we did wrong, either. If you get the answer, please post it (not just the answer, but the method of solving the problem).

It's also probably better to start a new thread with each new question -- so that others can learn also, and keep each question separate.