pH and salts 1.5 Flashcards
what is Kw
ionic product
Kw calculation
[H3O+] [OH-]
Kw at room temperature
1.01 x 10^-14
what are [H3O+] and [OH-] in neutral solutions
1 x 10^-7
why are [H3O+] and [OH-] in neutral solutions low
because equilibrium lies far to the left
why can water act as both an acid and a base
because of its ions
amphoteric
when water act as both an acid and a base
pH + pOH =
14
how are salts made
by neutralisation reactions
salt’s properties
can be soluble (evaporation) or insoluble (filtration) and are strong electrolytes (completely ionised in solution)
what acid base reaction are soaps
weak acids and strong base
buffers
a solution that stays approximately the same pH when small amounts of acid, base or water are added
acid buffers
made from a weak acid and one of its salts made with a strong base
adding a base to an acid buffer
the weak acid can provide H+ ions to replace the ones removed by the base
adding an acid to an acid buffer
the salt provides the conjugate base which can absorb the excess H+ ions
basic buffers
made from a weak base and one of its salts (conjugate acid)
adding an acid to a basic buffer
weak base removed excess H+ ions
adding a base to a basic buffer
conjugate acid supplies H+ ions
indicators
determines the end point, are weak acids
what reactions are indicators not needed
weak acid-weak base titrations as pH won’t change quickly
