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# Equilibrium Constants from moles Watch

1. Any help is appreciated!

For the equilibrium:
H2(g) + I2(g) = 2HI (g)

When 0.5 mol of H2 (g) and 0.18 mol of I2 (g) were heated to 500C the equilibrium mixture contained 0.01 mol of I2 (g). Calculate the equilibrium constant Kc for this reaction.

So far I think I'm half there:

H2 + I2 = 2HI
Initial moles: 0.5 0.18 0
At equil: 0.01
Equil conc: 0.33/V 0.01/V 0.34/V

From this I determined that 0.17 mol of Iodine was being used so therefore 0.17 mol of Hydrogen were used to give the 2HI 0.34 mol

From this Kc = [HI]2 / [H2] [I2]
Kc = 0.34/V / 0.33/V . 0.01/V

Any advice to where the theory went wrong or another method of calculating the Kc is appreciated. Thanks in advance!
2. (Original post by RedPixieDust)
Any help is appreciated!

For the equilibrium:
H2(g) + I2(g) = 2HI (g)

When 0.5 mol of H2 (g) and 0.18 mol of I2 (g) were heated to 500C the equilibrium mixture contained 0.01 mol of I2 (g). Calculate the equilibrium constant Kc for this reaction.

So far I think I'm half there:

H2 + I2 = 2HI
Initial moles: 0.5 0.18 0
At equil: 0.01
Equil conc: 0.33/V 0.01/V 0.34/V

From this I determined that 0.17 mol of Iodine was being used so therefore 0.17 mol of Hydrogen were used to give the 2HI 0.34 mol

From this Kc = [HI]2 / [H2] [I2]
Kc = 0.34/V / 0.33/V . 0.01/V

Any advice to where the theory went wrong or another method of calculating the Kc is appreciated. Thanks in advance!
The first bit looks right to me, but did you remember to square the concentration of [HI] to get Kc? Also, don't forget the units

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