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Chem0150f10ch3a(2)

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Chem0150f10ch3a(2)

  1. 1. General Chemistry 0150 Instructor: Professor Voytek Fall 2010 Chapter 3: Measurements and Problem Solving
  2. 2. WHAT IS CHEMISTRY? Chemistry is the study of matter and its properties , both at the macroscopic as well as at the atomic , subatomic and molecular levels. Chemists seek to understand the composition of matter, the changes that matter undergoes as well as the energy associated with these changes. Matter is anything that has mass and volume . It is the stuff of life. Everything around us (including us) is made up of matter.
  3. 3. SOME DEFINITIONS Chemical Properties those which the substance shows as it interacts with, or transforms into, other substances Change(s) in composition but mass is conserved Matter anything that has mass and volume -the “stuff” of the universe. Composition What the matter is made of and how much each substance is present. Properties The characteristics that give each substance a unique identity . Physical (Intensive) Properties those which the substance shows by itself without interacting with another substance No change(s) in composition (such as State of Matter)
  4. 4. Classifying Matter according to composition
  5. 5. Practice Questions <ul><li>Classify each of the following substances as element, compound, homogeneous or heterogeneous mixtures: </li></ul><ul><li>1)methane CH 4 </li></ul><ul><li>2)aluminum can </li></ul><ul><li>3)rocky road ice cream </li></ul><ul><li>4)tap water </li></ul><ul><li>5)distilled water </li></ul>
  6. 6. I-Clicker Question <ul><li>Baking soda (NaHCO 3 ) would be classified as: </li></ul><ul><ul><li>A)element </li></ul></ul><ul><ul><li>B)compound </li></ul></ul><ul><ul><li>C)heterogeneous mixture </li></ul></ul><ul><ul><li>D)homogeneous mixture </li></ul></ul>
  7. 7. Some Characteristic Properties of Copper DESCRIBING MATTER according to its PROPERTIES Physical Properties reddish brown, metallic luster easily shaped into sheets (malleable) and wires (ductile) good conductor of heat and electricity density = 8.95 g/cm 3 melting point = 1083 ° C boiling point = 2570 ° C Chemical Properties slowly forms a basic blue-green sulfate in moist air reacts with nitric acid and sulfuric acid slowly forms a deep-blue solution in aqueous ammonia
  8. 8. Telling matter apart (according to properties) <ul><li>Physical properties - properties that a substance displays without changing its composition </li></ul><ul><ul><li>Odor, color, taste, appearance, melting, boilig, freezing, weight, density </li></ul></ul><ul><li>Chemical properties - properties displayed only through changing its composition to yield a new substance </li></ul><ul><ul><li>combustion, oxidation, reduction, acid/base reactions </li></ul></ul>
  9. 9. PHYSICAL AND CHEMICAL CHANGES
  10. 10. PHYSICAL AND CHEMICAL CHANGES
  11. 11. PHYSICAL AND CHEMICAL CHANGES
  12. 12. I-Clicker Question Frost forms as the temperature drops on a humid winter night. A)physical change ? B)chemical change ?
  13. 13. I-Clicker Question A sunflower grows from a seed that is watered and fertilized. A)physical change ? B)chemical change ?
  14. 14. Mixtures can be converted to pure substances by a physical processes such as through a filtration, distillation, chromatography, centrifuging, evaporation or sublimation to name a few.
  15. 15. Mixtures can be converted to pure substances by a physical processes such as through a filtration, distillation, chromatography, centrifuging, evaporation, extraction, reverse osmosis or sublimation.
  16. 16. A magnet can be used to separate iron metal from crystals of potassium dichromate:
  17. 17. Law of Conservation of Mass <ul><li>During physical and chemical changes, the total amount of matter remains the constant. </li></ul><ul><li>In other words: </li></ul><ul><li>Matter can neither be created nor destroyed </li></ul><ul><li>This is known as the Law of Conservation of Matter (mass) </li></ul>
  18. 18. Law of Conservation of Mass <ul><li>Butane + Oxygen -> Carbon Dioxide + Water </li></ul><ul><li>58g + 208g -> 176g + 90g </li></ul><ul><li>Reactants -> Products </li></ul><ul><li>266g = 266g </li></ul><ul><li>Determine whether or not a matter is created, destroyed or conserved given the following: a chemist forms 16.6g of NaCl from 3.9g of Na and 12.7g of Cl. </li></ul>
  19. 19. I-Clicker Question <ul><li>12g of natural gas combines with 48g of oxygen to form 33g of carbon dioxide and 20g of water. Is matter </li></ul><ul><li>a)conserved </li></ul><ul><li>b)created </li></ul><ul><li>c)destroyed </li></ul>
  20. 20. DESCRIBING MATTER according to its STATE “The Four States of Matter” <ul><li>Solids: A substance with a fixed shape that will not conform to its container. </li></ul><ul><li>Liquids: A substance that conforms to the container but will retain its own </li></ul><ul><li>volume. </li></ul><ul><li>Gas: A substance that both conforms to the container and fills the entire volume </li></ul><ul><li> of the container. </li></ul>
  21. 21. DESCRIBING MATTER according to its STATE “The Four States of Matter” <ul><li>Plasma: A substance composed of ionized gas. It is the most common of </li></ul><ul><li>all phases in the universe (space is comprised of sparse plasma); 99% of the </li></ul><ul><li>known universe is in the plasma state. </li></ul><ul><li>Common Plasma’s: </li></ul><ul><li>Sun </li></ul><ul><li>Stars </li></ul><ul><li>Neon Signs </li></ul><ul><li>Plasma TV’s (made of tiny cells that contain noble gases) </li></ul><ul><li>*changes in state are physical properties of matter </li></ul>

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