Making salts Flashcards
Are nitrates soluble or insoluble?
soluble
which carbonates are insoluble
Ammonium, potassium and sodium carbonate
most sulfates are soluble, which isn’t?
Barium and calcium sulfate
most chlorides are soluble, which isn’t?
silver chloride
Making soluble salts using acids and insoluble bases….
Pick an acid and an insoluble base (most metal oxides, carbonates and hydroxides are insoluble). If you wanted to make copper nitrate you could use nitric acid and copper carbonate. Add the metal oxide, carbonate or hydroxide to the acid and the solid base will dissolve as it reacts. The acid will have been neutralized when the excess solid sinks to the bottom and stays there. To get the salt solution you filter off the solid with filter paper and the evaporate off the water to form crystals of salt.
Making soluble salts using an alkali…
Alkalis are soluble bases so you cant filter them off with filter paper if you add to much - you cant tell when you’ve added too much. You must add exactly the right amount of alkali to just neutralise it so you must use an indicator. the best way of doing this is with titration. Then repeat the experiment using the same volume of acid and alkali but without the indicator so the salt isn’t contaminated.
Making insoluble salts…
This is a precipitation reaction. you pick two solutions with the ions you want e.g. if you wanted to make barium sulfate you would use barium chloride and sulfuric acid.
BaCL2 + H2S04 goes to BaSO4 + 2HCL
you just mix two solutions containing the ions you need
when making soluable salts with acids and insoluable bases how can you tell when the acid has been neutralised?
when excess solid sinks to the bottom and stay there.
How do you get the salt solution from the acids and insoluable bases method? The salt crystals?
Filteroff the solid with filter paper. Evaporate off the excess water.
In which making salts method do you just mix the ions you want? What is this reaction called?
Making insoluable salts. Precipitation reaction.
In which method must you use titration because the you cannot use filter paper? Why?
Making soluable salts using an alkali. You cannot use filter paper because alkalis are soluable so you cannot filter off the excess. You use titrations so you see when its neutralised.
When you use the ‘making soluable salts with an alkali method’ why must you repeat the experiment?
So the salt is not contaminated by the indicator you had to use for the titration.
