Required practical - Separating mixtures

produce a pure, dry sample of a soluble salt from an insoluble oxide or carbonate.

­­Use a Bunsen burner to gently warm the acid. Add the insoluble solid (with stirring) until the reaction no longer happens. Filtration - Filter the solution to remove the excess insoluble solid. This will leave a solution of the salt dissolved in water. Crystallisation - Heat the solution in an evaporating basin above a beaker of water. The ‘water bath’ ensures gentle heating. Let the solution cool and allow more water to evaporate. As water evaporates, the solution will become more concentrated and the salt will begin to crystallise.

• start with a fixed amount of your dilute acid, and heat it in a beaker above a heatproof mat until its almost boiling • using a spatula, add small amounts of the base to the acid, and stir with a glass rod • the base will react and seem to disappear - continue adding more of the base in excess if you dont get the right colour - stop adding the base if powder still remains after stirring • at this point the reaction has stopped, as all of the acid has reacted • Use a filter funnel and filter paper to remove the unreacted base • Take the solution and place it in an evaporating basin • heat it gently over a water bath • heat it until half of the solution remains • leave the solution for 24 hours in a cool place for crystals to form • scrape the crystals onto a paper towel and gently pat dry

if theres any left at the end, it would contaminate our salt

because it could bubble over when we add our other reactant ,and that would be dangerous