Question

PLEASE PLEASE HELP URGENT :(

Suppose that your teacher has just given you three test tubes which appear to look
the same. You are told on is a solution of calcium chloride, another is a suspension of
calcium carbonate, and the third a colloid, which contains water to which a little milk
has been added. Explain how you could tell the contents of each test tube.

Answer 1

To distinguish the contents of each test tube, some simple tests can be performed:

For the calcium chloride solution: a small amount of silver nitrate solution can be added to the test tube. If a white precipitate forms, this indicates the presence of chloride in the solution.

For calcium carbonate suspension: A few drops of dilute hydrochloric acid can be added to the test tube. If an effervescence occurs, this indicates the presence of carbonate in the suspension.

For the milk colloid: the appearance of the contents of the test tube can be observed. If the content appears cloudy and opaque, this indicates the presence of a colloid. Also, if a pH indicator such as phenolphthalein is added, the solution will remain pink, indicating that there is not a significant amount of acid or base present in the solution.