Plan and make a named salt sim
Get a target salt, decide whether it is soluble and which method to use, take the chemicals from the shelf, see what really happens when a choice is wrong, and have your plan marked.
Acids, bases and salts: choosing and carrying out a method to prepare a salt · covers the O-Level, IGCSE, GCSE topic
What the sim shows
To plan a salt preparation, ask two questions. Is the salt soluble? If not, make it by precipitation: mix two solutions that hold its ions, filter, keep the residue, wash it with distilled water and dry it. If it is soluble, is it a sodium, potassium or ammonium salt? If so, use a titration: the alkali and the acid are both soluble, so neither can be added in excess and filtered off; find the exact volumes with an indicator, repeat without it, then evaporate to saturation and crystallise. Otherwise, add an insoluble metal, base or carbonate to the acid until some is left over (excess), filter off the excess, keep the filtrate, evaporate to saturation, let crystals form, and dry them between filter papers. Wrong choices do what they really do: copper does not react with dilute acids; sodium is far too dangerous to add to acid; calcium carbonate with sulfuric acid stops early because insoluble calcium sulfate coats it; an insoluble solid cannot take part in a precipitation. The amounts: 25.0 cm³ of 1.00 mol/dm³ acid (or 0.500 mol/dm³ solutions for a precipitation, the other in excess); about 65 % of a soluble salt is collected as crystals (the rest stays in the solution) and 95 % of a precipitate. Model limits: these recovered fractions are typical, not measured; the burette's top runs out of the picture; the drying oven is not drawn.
- Shelf: 1–12 solutions, 13–24 solids
- Gauze: the reaction beaker, then the evaporating basin
- Burette and tile: for a titration
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