2.g- Acids, bases and salt preparations Flashcards
describe the production of a pure salt from an insoluble base and acid
eg. copper (11) sulphate (blue salt crystals) from copper oxide and sulphuric acid
- acid + insoluble base ( metal oxide / metal hydroxide)
- heat acid gently in a water bath ( do not let it boil) (speeds up reaction)
- add base to acid and stir with glass rod until all has dissolved
- continue adding base to acid until no more will dissolve ( base in excess= no left over acid in product )
- filter solution into conical flask
- heat the solution gently in an evaporating basin using a Bunsen burner to slowly evaporate some of the water
- leave solution to cool and allow the salt to crystallise
- filter off the solid salt and allow it to dry.
general rules for predicting solubility of compounds in water
- common sodium , potassium + ammonium
soluble
general rules for predicting solubility of compounds in water
- all nitrates
soluble
general rules for predicting solubility of compounds in water
- common chlorides , except those of silver and lead (II)
soluble
general rules for predicting solubility of compounds in water
- common sulphates , except for those of barium, calcium and lead ( II )
soluble
general rules for predicting solubility of compounds in water
- common carbonates, except sodium potassium and ammonium
insoluble
general rules for predicting solubility of compounds in water
- common hydroxides , except those of sodium, potassium + calcium
insoluble
understand acid and base in terms of proton transfer
???
name of acid + base reaction
proton transfer
why is acid + base called proton transfer
acid = proton donor = H+ ions
base = proton acceptor = OH- ions
what is formed during a neutralisation reaction
a salt
acid + base = salt + water
acid to salts
hydrochloric acid =???
sulphuric acid = ???
nitric acid = ???
chloride salts
sulphate salts
nitrate salts
acid + metal oxide =???
salt + water
acid + metal hydroxide = ???
salt + water
acid + ammonium
ammonium salt ( eg. ammonium sulphate )
metal + acid = ???
MASH
salt + hydrogen ( don’t worry about reactions with nitric acid + metals )
acid + metal carbonate = ???
salt + water + carbon dioxide
what are 3 compounds can act as bases
metal oxides
metal hydroxides
ammonia
what can :
metal oxides
metal hydroxides
ammonia
act as ???
bases
what are alkalis ( in terms of bases )
bases that are soluble in water
PAPER 2
describe an experiment to prepare a pure dry sample of a soluble salt starting from an acid and alkali
- titration using an indicator
- after titration solution that remains when the reaction is complete contains only salt and water
- slowly evaporate some of the water
- leave solution to crystallise
- filter of solid + dry it = pure dry salt
PAPER 2
how can you make soluble salts
acid alkali reactions
PAPER 2
how can you make insoluble salts
precipitation reactions
PAPER 2
describe an experiment to prepare a pure, dry sample of an insoluble salt starting from 2 soluble reactants
eg. make lead sulphate ( insoluble ) from mixing lead nitrate + magnesium sulphate = ( both insoluble )
- add 1 spatula of lead nitrate to a test tube + add water to dissolve it ( should use deionised water = no other ions about )
- in a separate test tube do the same with 1 spatula of magnesium sulphate
- tip 2 solutions into a beaker + stir = lead sulphate should precipitate out
- but filter paper into filter funnel + stick funnel into conical flask
- pour contents of beaker into the middle of filter paper
- swill out the beaker with more deionised water + tip into filter paper = makes sure you get all the precipitate from the beaker
- rinse contents of filter paper with deionised water = all soluble magnesium nitrate has been washed away
- scrape lead sulphate onto fresh filter paper + leave to dry in oven or a desiccator
