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Learn about pure substances and mixtures, their properties, and how they can be separated using physical and chemical methods. Includes examples and interactive learning checks.
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Pure Substances(elements and compounds) 1. EVERY SAMPLE of a given pure substance has EXACTLY THE SAME characteristic properties. a. Boiling point • Freezing point • Melting point • Density 2. Can NOT BE SEPARATED by PHYSICAL means Ex: water always has a boiling point of 100 C, melting point of 0 C, freezing point of 0 C and a density of l.00 g/ml. Other pure substances have their own individual characteristics (bp, mp, fp, density)
2 kinds of mixtures Mixture – • Not the same as a compound. Usually composed of several substances. • CAN be separated by PHYSICAL means
1.Homogeneous mixtures – also called solutions have the same composition throughout. Ex: salt water
2. Heterogeneous mixtures – the composition is NOT the same throughout; Ex: blue cheese dressing, sand and water, trail mix
Learning Check Learning Check: Identify the following as pure substances (p) or mixtures (m): ___ Oxygen (O2) ___ Lemonade ___ Snickers bar ___ Distilled water ___ Dry ice ___ Soil P M M P P M
Learning Check Learning Check: Classify the following as Homogeneous (ho) or Heterogenous mixtures (he) ___ Pure Air ___ Salsa ___ Chocolate chunk ice cream ___ Ink ___ Blood ___ Chicken noodle soup Ho He He Ho Ho He
Physical Separation:Separates MIXTURES 1.Distillation – based on differences in boiling point: separating a mixture of alcohol and water. Alcohol has a lower boiling point than water so it will boil off sooner. Both substances will be retained
Physical Separation:Separates MIXTURES 2.Filtration – based on differences in solubility and particle size -liquid is passed through materials with very small holes to strain out particles.
Physical Separation:Separates MIXTURES 3.Chromatography – based on differences in polarity Example Video
Physical Separation:Separates MIXTURES 4.Magnetism – separating iron and sand
Chemical Separation: Separates COMPOUNDS Electrolysis – a method of separating compounds (pure substances). This is NOT a physical separation, but a chemical separation using electricity. Waterhydrogen + oxygen
Learning Check Which method would be appropriate for separating these mixtures? _______________ Sawdust and water _______________ Nails and dirt _______________ Water and vinegar Filtration Magnetism Distillation
