12/14 Chemical Equilibrium Free Online FlashCards

What is dynamic equilibrium?

A dynamic state in which forward and reverse reactions continue at equal rates, so macroscopic concentrations remain constant.

Are reactant and product concentrations equal at equilibrium?

No. Equilibrium concentrations are constant, but they are not necessarily equal; equal forward and reverse rates define equilibrium.

Write Kc for aA + bB ⇌ cC + dD.

For aA + bB ⇌ cC + dD, Kc = [C]^c[D]^d / ([A]^a[B]^b), using equilibrium molar concentrations.

Why are pure solids and liquids omitted from K expressions?

Pure solids and pure liquids are omitted because their activities are effectively constant.

What is Kp for CaCO3(s) ⇌ CaO(s) + CO2(g)?

For CaCO3(s) ⇌ CaO(s) + CO2(g), Kp = PCO2 because the pure solids are omitted.

What does the magnitude of K indicate?

A large K favors products, a small K favors reactants, and K near 1 indicates appreciable amounts of both.

How does Q differ from K?

Q uses the same algebraic form as K but uses concentrations or pressures at any moment, not necessarily at equilibrium.

How does comparing Q with K predict reaction direction?

If Q < K, the net reaction proceeds toward products; if Q > K, it proceeds toward reactants; Q = K means equilibrium.

What happens when volume decreases in the Haber reaction?

For N2(g) + 3H2(g) ⇌ 2NH3(g), decreasing volume shifts equilibrium right because the product side has fewer gas moles.

Does adding an inert gas at constant volume shift equilibrium?

At constant volume, adding an inert gas does not change reacting species’ partial pressures, so equilibrium does not shift.

How does increasing temperature affect endothermic and exothermic equilibria?

For an endothermic reaction, increasing temperature shifts equilibrium toward products; for an exothermic reaction, it shifts toward reactants.

What effect does a catalyst have on equilibrium?

A catalyst increases both forward and reverse reaction rates, reaching equilibrium faster without changing equilibrium concentrations or K.