2NO(g) Br2(g) 2NOBr(g) Assuming that you start with equal concentrations of NO and Br2 and no NOBr is initially present, describe the relative abundance of each species present at equilibrium.

E: [NO]= i-2x; [Br2]=i-x ; [NOBr]= x ***i= initial concentration

The concentration of both reactants is going to decrease because its consumption in the reaction, but not in the same proportion. NO is consumed in a double proportion than Br2, it means that at equilibrium there is going to be less NO present. The formation of NOBr is 1:1 with Br2, so the amount of Br2 consumed is the same than the NOBr produced.

Explanation:

We have the reaction:

2NO(g) + Br2 ⇄ 2NOBr (g)

ICE

The question give us the initial concentrations, and we need to find the final ones when the equilibrium is reached. We use the ICE (initial, change and equilibrium concentration analysis):

I: [NO]=i; [Br2]=i ; [NOBr]=0 **** i= initial concentration

C: -2x; -x; +x

E: [NO]= i-2x; [Br2]=i-x ; [NOBr]= x

The concentration of both reactants is going to decrease because its consumption in the reaction, but not in the same proportion. NO is consumed in a double proportion than Br2, it means that at equilibrium there is going to be less NO present. The formation of NOBr is 1:1 with Br2, so the amount of Br2 consumed is the same than the NOBr produced.

Kc

The relative abundance of each species is determined by the Kc of the reaction.

Because the question does not tell us that information, nor the temperature at which it occurs, we cannot calculate any concentration value.