For the reactions system 2h2(g) + s2(g) 2h2s(g), a 1.00-liter vessel is found to contain 0.5 mole of h2 , 0.02 mole of s2, and 68.5 moles of h2s. what is the equilibrium constant expression? what are the chemical formulas, not numbers. (enter subscripts after the letters: for example, h2o = hs2o. also, don't forget to use the proper chemical shorthand for chemical symbols. for instance, chlorine = cl but not cl or cl.) and : )

First you calculate the molarity of all components in equilibrium :

Volume = 1.00 liter

For H₂ :

M =  n / V

M =  0.5 / 1.00

M = 0,5 mol/L^-1 

For S₂ :

M = 0.02 / 1.00

M = 0.02 mol/L^-1

For H₂S :

M = 68.5 / 1.00

M = 68.5 mol/L^-1

the equilibrium constant expression :

Kc = products / reagents

         Reagents        products    
             ↓                     ↓
2 H₂(g) + S₂(g) =    2 H₂S(g) 

Kc = [ H₂S ]^2 / [ H₂ ]^2 * [ S2 ]

Kc =  [ 68.5 ]^2 / [ 0.5 ]^2 * [ 0.02 ]

Kc = [ 4692.25] / [ 0.25 ] * [ 0.02 ]

kc = [ 4692.25] / [ 0.005 ]

kc = 988450

hope this helps!