(a) Chemical equilibrium

when is a chemical reaction in equilibrium

when the composition of the reactants and products remains constant indefinitely

what does the equilibrium constant (k) characterise

The equilibrium composition of the reaction mixture

what does the value of an equilibrium constant indicate

the position of equilibrium

what are the concentrations of pure solids and pure liquids at equilibrium taken as

Constant and given a value of 1 in the equilibrium expression

what does the numerical value of the equilibrium constant depend on

the reaction temperature and is independent of concentration and/or pressure

what does an endothermic reaction cause when temperature is increased

increase in k and the yield of product is increased

What does an exothermic reaction cause when temperature is increased

A rise in temperature causes a decrease in k and the yield of the product is decreased

What is the effect of a catalyst on the value of the equilibrium constant

No effect

In water and aqueous solutions what is the equilibrium between

water molecules and hydronium (hydrogen) and hydroxide ions

What is water

Amphoteric (can react as an acid or base)

What does the brønsted-lowry theory state about acids

Acid is a proton donor

how is a conjugate base formed from an acid

by the loss of a proton

how is a conjugate acid formed from an base

by the gain of a proton

what happens to strong acids and bases in aqueous solution

completely dissociated into ions

what happens to weak acids and bases in aqueous solution

partially dissociated into ions

what are examples of strong acids

hydrochloric acid, sulfuric acid and nitric acid

what are examples of weak acids

Ethanoic acid, carbonic acid and sulfurous acid

what are examples of strong bases

Solutions of metal hydroxides

what are examples of weak bases

Ammonia and amines

A soluble salt of a strong acid and strong base dissolves in water to produce

neutral solution

A soluble salt of a weak acid and strong base dissolves in water to produce

alkaline solution

A soluble salt of a strong acid and a weak base dissolves in water to produce

acidic solution

What is a buffer solution

Where pH remains approximately constant when small amounts of acid, base or water are added

What does an acid buffer consist of

Solution of a weak acid and one of its salts made from a strong base

What does the weak acid do in an acid buffer

Provides hydrogen ions when these are removed by the addition of a small amount of base. Th salt of the weak acid provides the conjugate base which can absorb excess hydrogen ions produced by the addition of a small amount of acid

What does a basic buffer consist of

Solution of a weak base and one of its salts

What does the weak base do in a basic buffer solution

Removes excess hydrogen ions, and the conjugate acid provided by the salt supplies hydrogen ions when these are removed

What are indicators

Weak acids

What is the colour of an acid indicator in aqueous solution

Distinctly different from the conjugate base