Section 18.1 Equilibrium: a state of dynamic balance.

At any given temperature

Density does not change.

Standard conditions

298 K and one atm pressure.

Homogenous equilibria

All reactants and products are in the same physical state.

Homogeneous equilibrium

All the reactants and products are in the same physical state.

Sublimation

Forward process

Square brackets

Indicate the molar concentrations of the reactants and products at equilibrium in mol/L

Chemical equilibrium

Is a state in which the forward and reverse reactions balance each other because they take place at equal rates.

Value of Keq

Is constant only at a specified temperature

Concentration of a pure substance

Is its density in miles per liter

Equilibrium constant

Keq is the numerical value of the ratio of product concentrations to reactant concentrations.

Equilibrium constant expression

Keq= [C]c[D]d/[A]a[B]b

Keq>1:

More products than reactants at equilibrium

Keq<1:

More reactants than products at equilibrium

Reversible reaction

One that can occur in both the forward and the reverse directions

Equilibrium

Opposing processes are in balance.

When a reaction results in almost complete conversion of reactants to products

Reaction goes to completion.

Law of chemical equilibrium

States that at a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value.

Note:

That equation for the production of ammonia has a negative standard free energy, 🔼G.

The rate of a reaction depends upon

The concentration of the reactants.

At equilibrium

The concentrations of reactants and products are constant.

When each set of equilibrium concentrations are put into the equilibrium Constant expression

The value of Keq is the same.

If the reactants are not consumed

Then not all the products predicted by the balanced chemical equation will be produced

Heterogenous equilibrium

When the reactants and products of a reaction are present in more than one physical state.

General equation for a reaction at equilibrium

aA+bB<---> cC+dD