a solubility investigation
A SOLUBILITY INVESTIGATION
AIM: To investigate the precipitation reaction through the mixing of several ionic solutions.
THEORY:
A substance is classified as being soluble if it dissolves in a liquid. Conversely, a substance is insoluble if it does not dissolve in a liquid (Chemistrydaily.com, 2005). It is known that solutes dissolve more readily in solvents with similar molecular structures (Senese, 2004).
When two substances are added to together, at times, a reaction will occur. When a solid is formed in an aqueous solution, this reaction is called a precipitation reaction. Precipitation is the formation of an insoluble solid within a liquid. It occurs as the result of the reaction between two or more soluble substances (Tiscali.reference, 2005). It is known to occur when one type of cation from one solution combines with the anion of the other solution to form the insoluble substance (Smith, 1996, p. 91).
Solubility rules exist, displaying the solubility of substances and the exceptions which occur. Solubility rules state that all group 1 salts are soluble, all nitrates are soluble, chromates are frequently insoluble and most silver salts are insoluble (Busch, 1998).
HYPOTHESIS: When two solutions are mixed, a precipitate will be formed if one of the solutions is slightly insoluble.
MATERIALS:
Sodium chromate: Na2CrO4
Potassium chromate: K2CrO4
Potassium nitrate: KNO3
Sodium chloride: NaCl
Silver nitrate: AgNO3
PROCEDURE:
1. Observations of the solutions were recorded.
2. Na2CrO4 was added to K2CrO4.
3. Observations were recorded in a table.
4. Steps 3 and 4 were repeated for each of the combinations of solutions.
5. When a precipitate was formed, the solution was filtered to determine both the colours of the liquid and solid.
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