salt preparation Flashcards
what are all soluble salts?
all sodium + potassium + ammonium + nitrate salts
which salts are all soluble except for lead (ii) and silver?
chloride + bromide + iodide salts
what sulfate salts are insoluble?
barium + lead (ii) + calcium
what are the only carbonates that are soluble?
group1 metals + ammonium carbonates
what are the only hydroxides that are soluble?
group 1 + calcium + barium hydroxides/oxides
what is the only soluble lead compound?
lead (ii) nitrate
how do you make an insoluble salt?
precipitation
how do you make a soluble salt with a soluble base/carbonate?
titration
how do you make a soluble salt with an insoluble base/carbonate?
reaction of acid with excess insoluble bcm
what is a precipitate?
a solid that forms in a solution
what conditions must be met to form a precipitate?
both reactants must be in aqueous solution + products must be insoluble in water
what is the equation that represents the precipitation method?
AB (aq) + CD (aq) -> AD (s) + CB (aq)
what do you do if the starting reagent is an insoluble substance?
be converted into a soluble salt before the precipitation react can take place
what are the two reactions that can be expected from the titration method?
acid + alkali -> salt + water
acid + carbonate -> salt + carbon dioxide + water
what kind of salts are produced by titration?
salts of very reactive metals + ammonium
what are the conditions to be met for titration to be used?
both reactants are soluble and both products are soluble
why is an indicator used for titration?
there is no visible residue/undissolved solid reactants to indicate a complete reaction which may allow the salt to be contaminated with excess acid/base/carbonate
on a pH graph, what is the point called where the pH reaches 7?
equivalence point
what are the three reactions for reaction of acid with excess insoluble bcm?
acid + excess metal -> salt + hydrogen
acid + excess insoluble base -> salt + water
acid + excess onsoluble carbonatre -> salt + water + carbon dioxide
why is excess of the bcm added to the acid?
to ensure that all the sulfuric acid will be used up and prevents the salt solution will be contaminated with the acid
why is the mixture filtered?
to remove excess bcm
why is the mixture heated to about half or one-third its original volume?
to form a saturated solution for crystallization to occur
why is crystallization is used as opposed to heating to dryness?
heating to dryness would cause the salt to lose the water of crystallization
why are the crystals wash with cold distilled water?
so it does not dissolve crystals but is able to remove soluble impurities
