[ahawk1]

If the equilibrium constant for the reaction:

2HCl(g) <==> H2(g) + Cl2(g)

is 5.9x10-54 at 25oC, calculate the concentration of hydrogen gas in equilibrium with 0.018 mol of HCl in a 1.00-L container, assuming that only HCl was present originally.


ok so i started off by setting Kc=[H2][Cl2]/[HCl]^2 and then i get stuck on how to solve can someone help?

[plankk]

The good solution for that kind of problems is making the table. In it you can write how many reagents were at the beginning and how many reagents are in the equilibrium. So at first you have to calculate the intial concentration of HCl (the rest of reagents doesn't exist). Next you should notice that if the concentrations of Cl₂ and H₂ grow, the concentration of HCl decrease according to the reaction's equation. Next you should use the K and solve that equation.