G8 Synthesis and Analysis - Salts

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   acid      charcoal      evaporate      filtrate      indicator      insoluble      ions      lead      nitrates      potassium      precipitate      pure      silver      soluble      warm   
Salts are always made from an acid and an alkali.
All salts consist of , which are charged particles.
Not all salts are soluble.
Examples of salts in use today are...
Calcium sulphate - used as gypsum in plaster of Paris.
Potassium chloride - used by people cutting forn the sodium in their diet.
Cobalt sulphate - used as a pigment in paint.
Barium sulphate - used for barium meals in medicine.

Making a salt depends on whether the salt is soluble or in water.
Soluble SaltsInsoluble Salts
All chlorides except chloride and lead chloride
All sulphates exceptbarium sulphate and sulphate
and sodium carbonatesall other carbonates

Precipitation Reactions
Method for Insoluble Salts.
For example silver chloride is made from silver nitrate and sodium chloride. The silver chloride makes a solid which becomes a precipitate. The left over sodium and nitrate ions stay in solution.
There are 4 steps in this procedure.
1. Mix solutions of 2 salts that contain the right ions
2. Filter off the
3. Wash the precipitate with water
4. Leave the precipitate to dry at room temperature or in a oven.

Making soluble salts
Method 1 for Soluble Salts
1. Measure the right volume of into a beaker. Add the metal or insoluble oxide/hydroxde/carbonate a little at a time until no more dissolves.
2. Filter off the excess solid and collect the .
3. Heat the solution gently to some of the water.
4. Pour the concentrated solution into an evaporating dish and leave to cool and crystallise.

Method 2 for Soluble Salts
1. Measure the right amount of alkali or carbonate into a flask. Add a few drops of .
2. Add the gradually. Stop when the indicator changes colour.
3. Add a spatula of powder to absorb the indicator. Heat.
4. Filter to remove the charcoal powder.
5. Heat gently to .
6. Pour into a shallow dish and leave to cool and crystallise.