Consider the equilibrium system described by the chemical reaction below. When 1.50 mol of CO₂ and an 10.0 mol solid carbon are heated in a 20.0 L container at 1100 K,

Question

Consider the equilibrium system described by the chemical reaction below. When 1.50 mol of CO₂ and an 10.0 mol solid carbon are heated in a 20.0 L container at 1100 K, the equilibrium concentration of CO is 0.0700 M. Determine the concentrations of all species at equilibrium and then calculate the value of Kc for this reaction.

C(s) + CO₂(g) ⇌ 2 CO(g)

C(s) + CO₂(g) ⇌ 2 CO(g)

Initial (M) ( for each one C, CO₂ ,2 CO)

Change (M) for each one C, CO₂ ,2 CO) also for equilibrium

Equilibrium (M)

Based on the set up of your ICE table, construct the expression for Kc and then evaluate it. Do not combine or simplify terms.

Kc = ---- = __

Answer 1

So Ina S.,

what does an ICE table mean to you? IF it means nothing, then you need to go find a live tutor for some basic drilling.

If it means "Initial Change Eqilibrium", then we can go somewhere.

In particular, you can set up Initial for CO₂ (as M) and for CO (as M, it's 0). The C is a solid so it doesn't appear at all in the expression for the equilibrium constant!! Solids never do, and water (if it's the solvent) is also omitted by convention, even if it is one of the products or reactants.

So then you postulate some amount of change in CO₂ -- let's call it -x . It's negative b/c the CO₂ is decreasing, per the reaction. Then also by the reaction, the change in CO must be +2x . Why? It's an increase (positive), and the coefficient on the CO is a "2". So for every 1 molecule, or mole, or molar, of CO₂ that disappears, 2 molecules, or moles, or molar, of CO appear (whichever units you care to think in. Here, it makes sense to think in molar directly, since that is always the input to the equilibrium constant expression, isn't it).

So set up your ICE table: E = the equilibrium( = final) level for each material, which is initial + change, for that material. Then insert those E expressions into the equilibrium constant expression, and crank!

-- Cheers, --Mr. d.