[govibe]

Consider the following reaction at 1600°C.

Br2(g) 2 Br(g)
When 1.05 moles of Br2 are put in a 0.980 L flask, 1.20 percent of the Br2 undergoes dissociation. Calculate the equilibrium constant Kc for the reaction.

I know the Kc formula, but I can't calculate the concentrations

one more question

Is equilibrium when the products and reactants stay constant (but not necessarily equal) or is it when the products and reactants stay the same?

[Yggdrasil]

First calculate the number of moles of Br₂ and Br (if 1.2% of the Br₂ dissociates, how much Br₂ remains?  how much Br is created?).

Next, calculate the concentration (moles/volume).

Then, plug into the Kc expression.

Equilibrium is when the products and reactants stay constant (but not necessarily equal)