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Pure substances and mixtures

Pure substances and mixtures. S8P1b. Describe the difference between pure substances (elements and compounds) and mixtures. . Pure substance. Is matter that as uniform and unchangeable composition

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Pure substances and mixtures

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  1. Pure substances and mixtures S8P1b. Describe the difference between pure substances (elements and compounds) and mixtures.

  2. Pure substance • Is matter that as uniform and unchangeable composition • Examples include: pure water ( H2O is uniform always having 2 hydrogen atoms and one oxygen atom) vs. sea water (not uniform, its composition differs from place to place)

  3. Pure Substances • Uniform and Unchanging • Element – a pure substance that contains only one type of atom and cannot be broken down into simpler substances ( hydrogen, iron, and argon are elements) • Compound – made up of atoms of 2 or more elements ( Water is H2O, Salt is NaCl)

  4. Pure Substances

  5. Heterogeneous mixtures Homogeneous mixture • 2 or more substances mixed but not evenly distributed • Examples: granite, chocolate chip cookie, salad • also called solutions; 2 or more substances mixed with uniform distribution • Examples: salt water, soft drinks, air, metal alloys like brass and 14-carat gold Mixtures: 2 or more pure substances combined together

  6. S8P1d. Distinguish between physical and chemical properties of matter as physical (i.e., density, melting point, boiling point) or chemical (i.e., reactivity, combustibility).

  7. Physical Properties • Physical properties are used to identify, describe and classify matter. • Characteristic of a substance that can be observed (using your senses) without changing the substance into something else.

  8. More Examples of Physical Properties • size, shape, freezing point, boiling point, melting point, magnetism, viscosity, density, luster and many more. • Viscosity - The resistance of a liquid to flowing. • Examples: • Low viscosity-water, rubbing alcohol • High viscosity-honey

  9. Chemical Properties • Chemical properties are characteristics involved when a substance interacts with another substance to change its chemical make-up.

  10. Alike and Different • Draw a double bubble map in your notes to compare and contrast physical and chemical properties.

  11. http://www.youtube.com/watch?v=uJOGy0dgmUU

  12. S8P1e. Distinguish between changes in matter as physical (i.e., physical change) or chemical (development of a gas, formation of precipitate, and change in color).

  13. Physical Change • Physical changes occur when matter changes its property but not its chemical nature. • Physical property changes could include a change in: texture, shape, size, color, odor, volume, mass, weight, and density.

  14. Physical Change

  15. Chemical Change • Chemical changes are changes matter undergoes when it becomes new or different matter. • To identify a chemical change look for signs such as color change, bubbling and fizzing, light production, smoke, and presence of heat.

  16. Chemical Change • A chemical change occurs when fireworks are used. Fireworks are made of metals such as magnesium and copper. These change chemically as they light up the sky.

  17. Physical or Chemical Change? • Sugar dissolving in tea?

  18. Physical or Chemical Change? • Logs burning?

  19. Physical or Chemical Change? • Cutting paper?

  20. Physical or Chemical Change? • Crushing an aspirin?

  21. Physical or Chemical Change? • Metal rusting?

  22. Physical or Chemical Change? • Lighter fluid burning?

  23. Physical or Chemical Change? • An egg rotting?

  24. Physical or Chemical Change? • An egg breaking?

  25. http://www.youtube.com/watch?v=qqqmFFCwd7k

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