CHEMISTS CLASSIFY MATTER AS PURE OR IMPURE

Because atoms and molecules are so small, it is impractical to prepare a sample that is truly pure—that is, truly 100 percent of a single material. For example, if ju.st one atom or molecule out of a trillion trillion were different, then the 100 percent pure status would be lost. Samples can be purified by various merhods, however, such as distillation. When wc say pure, it is understood to be a relative term. Comparing the purity of two samples, the purer one contains fewer impurities. A sample of water that is 99.9 percent pure has a greater 

Milk (water, solid proteins) Blood (water, solid proteins) Fog (air, tiny water droplets) 

A homogeneous mixture may be either a solution or a suspension. In a solution, all components arc in the same pha.se. The atmosphere wc breathe is a gaseous solution consisting of the gaseous elements nitrogen and oxygen as well as minor amounts of other gaseous materials. Saltwater is a liquid solution because both the water and the dissolved sodium chloride are found in a sii lc 

Tap water, sparkling clean cooking pot, stove, knife 

Wear safety glasses for step i because some splattering may occur. 

Boil the water to dryness. (Turn off the burner before the water is all gone.The heat from the pot will finish the evaporation.) 

Examine the resulting residue by scraping it with the knife. These are the solids you ingest with every glass of water you drink. 

To see the gases dissolved in your water, fill a clean cooking pot with water and let it stand at room temperature for several hours. Note the bubbles that adhere to the inner sides of the pot. 

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