Equilibrium

Keq value

K = 1 , neither products or reactants favoured

small Keq = reactants favoured

large Keq = Products favored

ICE table

used to solve equilibrium problems

Heterogeneous reactions

Reactants and products are not all the same phase

Homogeneous reactions

all reactants and products are the in the same phase

Has different subscripts depending on situation, may need to be solved differently.

Keq = (products concentration)/(reactants concentration)

dimensionless

determines amounts of products and reactants at equilibrium

calculated in the same way as the Equilibrium Constant

measures amounts of reactants and products at a given point
during the reaction

can be used to figure out if a system is at equilibria

Q values

Q = 1 , system is at equilibrium

small Q = reaction will shift to make products

large Q = reaction will shift to make reactants

The Hundred Rule

If (initial concentration of reactant)/(Keq) > 100
Then the change in concentration can be discarded

Quadratic Formula

Sometimes problems will be set up in a way
where the quadratic Formula must be used.

Solubility Constant

Found in Data Booklet

Describes which Compounds are soluble or not

Partly Soluble or insoluble Compounds and Ksp

We write their Ksp using the product of the concentrations of their ions.

Arrhenius Acids and Bases

H3O+ will be produced when and acid reacts in water

OH- will form when a base reacts with water

Limited to solutions where water is the solvent

Bronsted-Lowry Acids and Bases

Each 'acid' on the reactants side has a conjugate base on the products side

An 'acid' gives away its Hydrogen atom in the reaction, conjugate base is formed on the products side

Each 'base' on the reactants side has a conjugate acid on the products side

A 'base' takes a Hydrogen atom in the reaction, conjugate acid is formed on the products side.

Amphoteric

acts as both an acid and a base

Water is amphoteric

Product constant of Water, Kw

Kw = 1.0 *10^-14 @ 25 Celcius

Kw changes with temperature

Kw can be calculated by finding the product of the concentration of Hydronium ions by Hydroxide ions

One molecule acts as an acid, the other as a base

Reaction of water and water

Acid Base Strength

Strong Acids and Bases

Ionize almost 100% in Water

No Equilibrium

Mostly ion sin solution

Strong acids will have waek conjugate bases

Strong bases will have weak conjugate acids

Weak Acids and Bases

Do not ionize completely

A weak acid will react to create a strong conjugate base

A weak base will react to create a strong conjugate acid

Acid Ionization Constant

Stronger acids have large Ka

Weak acids have small Ka

Base Ionization Constant

Stronger Bases have a large Ka

Weak Bases have a small Ka

Ka, Kb, and Kw

Ka * Kb = Kw

This equation can be rearranged to solve for what you need

A stronger acid(large Ka) will have a weaker conj. base(small Kb)

A stronger base (large Kb) will have a weaker conj. acid(small Ka)

Types of Equilibria

Chemical Reaction Equilibria

Phase Equilibria

Solubility Equilibria

reversible reaction

occurs at equal rates in dynamic equilibrium

reactions equation can go both ways

happens in a closed system

When stress is applied to a chemical system,
it will adjust to relieve that stress.

Stress

How is stress applied to a system?

Temperature

When heat is added to system, the endothermic
reaction is favoured

When heat is removed from system, the
exothermic reaction is favoured

The equilibrium constant stays constant only if
temperature is constant

Concentration

Addition of reactant or product causes the reaction
to react in a way that consumes the added substance

Removal of a reactant or product causes the reaction
to react in a way that produces the removed substance

Pressure/Volume

applies to gaseous equilibrium systems

Increase in air pressure (decrease in volume) will cause reaction to proceed in the direction which has the fewest
moles of gas

Decrease in air pressure (increase in volume) will
cause the reaction to proceed in the direction which
has the greatest moles of gas

disrupts equilibrium of a system

what doesn't cause stress(affect equilibrium)?

Addition of Catalyst

Addition of an Inert Gas

is reached when the solution is saturated with
dissolved ions

Solved in the same way as Equilibrium constant

Precipitates

Q > Ksp, solution is supersaturated, precipitate will form

Q < Ksp, solution is unsaturated, no precipitate will form

Q = Ksp , solution is saturated, no precipitate will form