Chemical Equilibrium (OG version)

The exact balancing of two processes, one of which is the opposite of the other

A dynamic state where the concentrations of all reactants and products remain constant.

Reactions in which the entire amount of the reactants are converted into product

A reaction which can be made to go in either direction

The rate (speed) of a reaction can be determined by the various concentrations of each species.

The concentrations stay the same until something else happens to disturb this equilibrium.

The Equilibrium Constant is constant at constant temperature.

The equilibrium constants changes as the temperature is varied. We do not include the concentration of pure solids or pure liquids in the expression.

– reactions occur in the same phase: The position of a heterogeneous equilibrium does not depend on the amounts of pure solids or liquids present. ▪ The concentrations of pure liquids and solids are constant.

– involve more than one phase:

K always has the same value at a given temperature regardless of the amounts of reactants or products that are present initially. • For a reaction, at a given temperature, there are many equilibrium positions but only one value for K . ▪ Equilibrium position is a set of equilibrium concentrations.

If K»_space; 1 e.g. 108 . The ratio of product concentrations to reactant concentration favours products. Equilibrium lies to the right

If K «_space;1 e.g. 10-10 . The ratio of product concentrations to reactant concentration favours reactants. There is no relationship between the rate of reaction and the numerical value of K.

Also referred to as molar concentration * Defined as the number of moles of solute dissolved in 1 litre of solution * Symbol M C = n/v The units are moles per litre (mol L -1 or M) c = concentration n = number of mols (mol) v = volume (L)

A narrow-necked flask which can be used to prepare an accurately known volume of solution * A graduation mark high on it’s neck * When filled ‘up to the mark’, the flask contains the volume given on the flask’ s label

A solution of relatively high concentration can be diluted with the same solvent to make a solution of the desired lower concentration

The choice of apparatus used depends on the precision required

When a solution is diluted, the number of moles of solute remains unchanged

Ionic compounds dissociate into their constituent ions when dissolved in water.