required practicals Flashcards
preparation of soluble salt practical
Add powdered insoluble reactant to acid in a beaker, one spatula at a time, stirring to mix.
Filter the mixture in the beaker to remove the excess powder. Collect the filtrate.
Pour the filtrate into an evaporating basin. Place on a water bath, and heat until about half the water from the solution has been removed by evaporation.
Stop heating when small crystals start to appear around the edge of the evaporating basin.
Pour the remaining solution into a watch glass, and leave in a warm, dry place for crystallisation to occur.
Determination of the reacting volumes of solutions of a strong acid and a strong alkali by titration
Use the pipette and pipette filler to add 25 cm3 of alkali to a clean conical flask.
Add a few drops of indicator and put the conical flask on a white tile.
Fill the burette with acid and note the starting volume.
Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
Stop adding the acid when the
end-point is reached (when the indicator first permanently changes colour). Note the
final volume reading.
Repeat steps 1 to 5
More accurate results are obtained if acid is added drop by drop near to the end-point.
electrolysis of aqueous solutions practical
hydrogen - lighted splint goes out with a squeaky pop
oxygen - a glowing splint relights
chlorine - damp blue litmus paper turns red and is then bleached white
