15.1-15.4 Quiz

Chemical equilibrium

Chemical equilibrium

the point at which the concentrations of all species are constant

Dynamic equilibrium

the point at which the rate od decomposition equals the rate of dimerization; opposing rates are equal

double arrow

implies process is dynamic

At equilibrium

[A] or k_f[A] decreases to a constant, [B] or k_f[B] increases from zero to a constant; [A] and [B] or k_f[A] = k_f[B] are constant

No matter the starting composition of reactants and products, the ______ ratio of concentrations is achieved at equilibrium

same

Equilibrium constant expression for a general reaction in the gas phase

K_eq = (products)^m/(reactants)ⁿ; K_eqis equilibrium constant

Law of Mass Action

expression of concentrations (partial pressures or molarities) of the reactants and products present at equilibrium

Equilibrium constant expression for everything in solution

K_eq = [products]^m/[reactants]ⁿ

K_eq

based on molarities of reactants nad products at equilibrium; omit units; same equilibrium established no matter the beginning; products/reactions; equilibrium constant

K_eq » 1

products dominate at equilibrium and the equilibrium lies ot the right

K_eq « 1

reactants dominate at equilibrium and the equilibrium lies ot the left

Equilibrium can be approached from ____ direction

any

K_eq reverse reaction

1/K_eq

When the stoichiometric coefficients of a reaction are multiplied by a factor c, K is

raised ot the power c

When reactions are added together, the K of the resulting overall reaction is

the product of the K’s for the reactinos that were summed

How are equilibrium constants for gas phase reactions expressed?

expressed partial pressures not concentrations since pressure is proportional to the concentration; P =MRT & M = P/RT

Homogeneous

all reactants and products are in one phase

Heterogeneous

one or more reactants or products are in a different phase

Concentrations of solids and pure liquids are

constant so ignore them in K_eq