Tbr lecture 3 passage 6 help please!

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yellowjellybean

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38. If 1.00 moles of both CO2 and H2 were mixed in a 1.00 liter container at 1000°C, what will the equilibrium concentrations be for both CO2 and H2?

A. [C021=0.57M;[H2]=0.57M
B. [CO2]=0.57M;[H2]=0.43M
C. [CO2I=0.43M;[H21=0.57M
D. [CO2I = 0.43 M; [H2] = 0.43 M

Keq = 0.569
CO(g) + H2O(g) <---> CO2(g) + H2(g)
Answer: D
Explanation: The equilibrium constant is less than 1.00, so the reactants are more abundant than the products. This means at equilibrium, both CO2 and H2 have concentrations less than half of their initial concentration (1.00 M). The only answer that shows this is choice D.

I've seen a thread on this but I'm still confused how you can assume that the have concentrations are less than half of their initial concentration based on the K of 0.569 when the equation for the equilibrium equation is (1-x)(1-x)/x^2 which I would think is too complicated to just look at the K and base the mole concentrations on. If some can break it down for me I'd be so grateful.

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I believe it is saying if Keq was 1 when you added the CO2 and H2 together half of each of those would become the products at equilibrium. So you would have 0.5M of everything.
Since Keq is lower than 1 it favors the reactants. And you don't need to do any ICE stuff because it's easy values for everything. 1 mole, 1 liter.

Mathy:
Keq = (product1)(product2)/(reactant1)(reactant2)
Keq = (CO2(g) + H2(g)) / (CO(g) + H2O(g))
initial = 1M*1M/0M*0M

From there it will shift but the products will need to be lower than the reactants with the result being
Keq = 0.569 = (0.43)(0.43)/(0.57)(0.57)
0.569 = 0.1849/0.3249

The point to the question was that you don't need to do any of that math because if your products/reactants is less than one you know the reactants will have a greater molar concentration. (more CO and H20)
 
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