reversible reactions and chemical equilibrium

some reaction

use —> in these reactions to symbolise that the reaction goes to completion forming the precasts on the RHSc

some reactions don’t go entirely to products

in these equations we use equilibrium arrow to indicate that the reaction can go either way. in equilibrium the forward and back reactions have not stopped but are proceeding at the same rate

types of reactions

• all products

• products and reactants

• all reactants

acids and bases

• acids is a proton donor

• base is a proton acceptor

strong acids

• strong acids are dully dissociated

• all dissolved HCI molecules are ionised

weak acids

acids that dissociate in a reversible reaction

buffers

• resists pH changes on addition of small amounts of acid or base to a system

• rely upon the effects of.a weak acid or base and the salt of that acid or base

making a buffer solution

• choose a weak acid with a pKa close to the required pH of the buffer

• choose an appropriate salt of the weak acid

• determine ratio needed to give correct pH