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More About Matter

More About Matter. Physical and Chemical Properties. Physical vs. Chemical Properties. Physical Properties Observed without changing identity of substance. Ex: color, hardness, density, odor, malleability, ductility, MP temp. Chemical Properties Observed during chemical changes

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More About Matter

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  1. More About Matter Physical and Chemical Properties

  2. Physical vs. Chemical Properties • Physical Properties • Observed without changing identity of substance. • Ex: color, hardness, density, odor, malleability, ductility, MP temp. • Chemical Properties • Observed during chemical changes • Ex: flammable, explosive, corrosive, rusts, decomposes

  3. Chemical vs. Physical Changes • Physical Change • Does not alter chemical composition. • Substance still has same chemical formula. • Ex: bend, cut, grind, dissolve, undergo a phase change • Chemical Change • Chemical composition changes as a reaction occurs. • New products formed. • Ex: cook food, sour milk, burn wood, explode dynamite

  4. What Type of Change?

  5. What Type of Change? • H2O(s) → H2O(l) • 2H2O (l) → 2H2(g) + O2(g) • NaCl(s) → NaCl(aq) • CH4(g) + O2(g) → CO2(g) + H2O(g)

  6. Is it Chemical or Physical? • Sometimes it is possible to determine a chemical change using the naked eye. • Things to look for: • Gas bubbles produced, unusual color change, new odor produced, precipitate forms • Precipitate: an insoluble solid that forms when two solutions are mixed.

  7. Types of Matter Pure Substance vs. Mixtures

  8. Elements (Pure Substance) Made up of atoms of one specific type Have specific physical and chemical properties. Cannot be broken down by chemical reactions • Ex: Fe, K, Na, Si

  9. Compounds (Pure Substance) Two or more different elements chemically bonded together. Have different chemical and physical properties than elements that make them up. Definite fixed proportions by mass. • Ex: C6H12O6, MgCl2, CO2, NaCl

  10. Mixtures Two or more pure substances physically combined. • Mixtures can be solid, liquid or gaseous.

  11. Mixture’s Composition is Not Fixed • Can vary depending on how much of each component is added.

  12. Retaining Their Properties • Substances in mixtures retain their own properties. • Ex: Iron filings (Fe) and sand (SiO2) • Even if mixed the iron retains its magnetic properties https://www.youtube.com/watch?v=88MBCyiaPSM

  13. Element, Compound or Mixture?

  14. Types of Mixtures

  15. Homogeneous Mixtures • Components are distributed uniformly at the molecular level. • All true solutions are homogeneous.

  16. If you see (aq) it is a homogeneous mixture • Aqueous = (aq) dissolved in water or “in solution” • Ex: NaCl (aq)

  17. How to Tell if a True Solution • Tyndall Effect • Suspensions and colloids have larger particles that will scatter a beam of light. In a true solution the light will not be scattered

  18. Heterogeneous Mixtures • Components are not uniformly distributed at the molecular level. • Colloids and suspensions are included in this category.

  19. Separating Mixtures • Components retain their own properties, so use these properties to separate them. • Ex: density, particle size differences, solubility differences, BP temperature, magnetic properties

  20. Filtration • Ex: Separate water & sand • Can be used to separate heterogeneous mixtures • Technique cannot be used to separate components of solutions

  21. Separatory Funnel • Ex: Separate oil and water • What type of mixture?

  22. Evaporation • Ex: Separate sugar from water • What type of mixture?

  23. Chromatography • Solvent runs up paper and components separate out along length of paper depending on level of attraction to solvent. • Ex: Separate different types of chlorophyll

  24. Distillation • Separates two or more liquids, due to differences in boiling point temp. • Ex: Separate alcohol and water • What type of mixture?

  25. Density Calculating

  26. Density • Because all matter has mass and volume, all matter has density. • No matter the size of the sample, the density doesn’t change. • It is a physical property. • See Reference Table S for the density of elements. D = M V https://www.youtube.com/watch?v=GnBQ6vIutDM

  27. Density of Water • Density of Pure Water = 1.0 g/ml • If a substance has a density greater than water it will sink, if not it will float. • When you dissolve a substance in water it makes it more dense. http://youtu.be/7xGo-HPGKmY

  28. Measuring Density (D = M/V) • Mass • Measured on a scale, often you need to use a weighing dish or a beaker. • Volume • Can be measured in different ways. • For solids the method of water displacement is often used.

  29. Density column http://youtu.be/-CDkJuo_LYs • Coke vs Diet coke http://youtu.be/5HCmRCGv37s

  30. Clips • Separating Mixtures • http://youtu.be/fJXBlfwB_Nw • Distillation • http://youtu.be/tcJXGIJA9Wo

  31. Cool Clips Showing Chemical Change • Chemical Reactions (Bill Nye) http://youtu.be/1MiVyBHQmJk http://youtu.be/66kuhJkQCVM • Steve Spangler (clock reactions) http://youtu.be/BqeWpywDuiY • Diet Coke and Mentos http://youtu.be/9vk4_2xboOE

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