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Find the concentration of product when reactant concentration at equilibrium is given using ICE equation

At a certain temperature, the equilibrium constant, Kc, for this reaction is 53.3.
H2 (g) + I2 (g) <---> 2HI (g)
At this temperature, 0.300 mol of H2 and 0.300 mol of I2 were placed in a 1.00-L container to react. What concentration of HI is present at equilibrium?

chemistry123 Thu, 03/07/2013 - 14:19


Set up a table of initial and final concentrations, where the change in concentration of each reactant is designated as x.

 Set up an ICE table. I is the initial concentration. C is the change. E is the equilibrium, which is just I + C.

In the reaction, the reactants are forming products. Therefore, the change would be -nx for reactants and +nx for products, where n is the stoichiometric amount.

     H2(g) +     I2(g) <-----> 2HI(g)
I    0.600        0.600            0
C    -x             -x               +2x
E  0.300-x     0.300-x          2x

Kc = [HI]^2 / [I2][H2]

53.3 = (2x)^2 / (0.300-x)^2

x = ?

Plug that value back into the equilibrium for [HI].

[HI] = 2x = ?