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Chapter two powerpoint

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Chapter two powerpoint

  1. 1. Chapter 2 Nina Bartell 8-3
  2. 2. 2.1
  3. 3. Pure SubstanceMatter that always has exactly the samecomposition is classified as a pure substance*every sample of a given substance has thesame properties because a substance has afixed, uniform compositioncan be classified into two categories-elementsand compounds
  4. 4. Elements and Atomsa substance that cannot be broken down into simplersubstancesan atom is the smallest particle of an element*an element has a fixed composition because itcontains only one type of atomno two elements contain the same type of atom
  5. 5. Compounds a substance that is made from two or moresimpler substances and can be broken downinto those simpler substancesThe simpler substances are either elements orother compounds
  6. 6. Mixture*the properties of a mixture can vary becausethe composition of a mixture is not fixedmixtures can be classified by how well theparts of the mixture are distributed throughoutthe mixture
  7. 7. Heterogeneous and homogenous mixturesHeterogeneous: the parts of a mixture arenoticeably different from one another (sand)Homogenous: the substances are so evenlydistributed that it is difficult to distinguish onesubstance from another(serving spoon-iron,chromium, and nickel)
  8. 8. Solutions/Suspensions/Colloids *Based on the size of its largest particles, a mixture can be classified as a solution, suspension, or colloid Solution: when substances dissolve and form a homogenous mixture Able to see through solutions that are liquids because light passes through them without going in all different directions Suspension: heterogeneous mixture that separates into layers over time
  9. 9. 2.2
  10. 10. Physical PropertiesAny characteristic of a material that can be observedor measured without changing the composition of thesubstances in the materialUsed to identify a material, to choose a material for aspecific purpose, or to separate the substances in amixtureviscosity, conductivity, malleability, hardness, meltingpoint, boiling point, and density are all
  11. 11. ViscosityThe tendency of a liquid to keep fromflowing, it’s resistance to flowingHoney has a high viscosity because it isvery resistant but water has a lowviscosity because it is not very resistant
  12. 12. ConductivityA material’s ability to allow heat to flowwould you use a metal or woodenspoon while stirring soup?A wooden one because it has lowconductivity so the top of the spoondoesn’t get hot and it won’t burn you
  13. 13. MalleabilityThe ability of a solid to be hammeredwithout shatteringGold is malleable because whenhammered, it doesn’t shatter but an icecube is not because if hammered, itwould shatterMost metals are malleable
  14. 14. Melting pointTemperature at which a substance changesfrom a solid to a liquidMelting point for water is 0˚c at sea level
  15. 15. Boiling PointTemperature at which a substance boilsBoiling point for water is 100˚c at sea level
  16. 16. DensityUsed to test the purity of a substanceRatio of the mass of a substance to its volume
  17. 17. Identifying a Material1. Decide which properties to test2. Do tests on the sample of the unknown3. Compare the results with the data reportedfor known materials
  18. 18. What are Properties?They determine which materials are chosen forwhat uses
  19. 19. Filtration and DistillationThese two terms are common separationmethodsFiltration: a process that separates materialsbased on the size of their particlesDistillation: a process that separates thesubstances in a solution based on their boilingpoints
  20. 20. What is physical change?The change of water from a liquid to a gasduring boilingThis occurs when some of the properties of thematerial change but the substances in thematerial stay the same
  21. 21. Ways of Separating a MixtureDistillationFiltrationEvaporation
  22. 22. Distillation A process that separates two substances in a solution based on their boiling points Distillation ApparatusUnknown SubstanceAlcohol Burner
  23. 23. FiltrationA process that separates materials based on thesize of particles +/or solubilityfilter paper goes inside filterthe mixture is poured into filter paperthe element left in the filter paper is thesubstance and the liquid at the bottom is topurified water (liquid)
  24. 24. EvaporationA process used to isolate a solid dissolved in aliquidex: NaCl+waterDisclaimer: water(liquid) will evaporate+youwon’t be able to isolate a sample of itmixture is poured into an evaporating dishwhich is heated and all that is left is thedissolved element that is now not dissolved
  25. 25. 2.3
  26. 26. Chemical PropertyAny ability to produce a change incomposition of matterChanges the composition of the substance*Chemical properties can only be observedwhen the substances in a sample of matter arechanging into different substances
  27. 27. FlammabilityA material’s ability to burn in the presence ofoxygenExample: alcohol and water
  28. 28. ReactivityA property that describes how readily asubstance combines with other substances.Example: Oxygen/Potassium
  29. 29. Chemical ChangeOccurs when a substance reacts and forms oneor more new substances*Three common types of of a chemical change:-change in color -the production of gas -theformation of a precipitate
  30. 30. PrecipitateAny solid that forms and separates from aliquid mixture
  31. 31. REVIEWQUESTIONS
  32. 32. #1 QUESTIONHOW MANY CATEGORIES ARE PURESUBSTANCES CLASSIFIED INTO? ANDWHAT ARE THOSE CATEGORIES?
  33. 33. #2 QUESTIONWHAT TYPE OF CHANGE DO YOU USEWHEN YOU WANT THE COMPOSITION OFTHE SUBSTANCES TO STAY THE SAME?
  34. 34. #3 QUESTIONWHAT TECHNIQUE WOULD YOU USE TOISOLATE A SOLUTION OF SALT ANDWATER?
  35. 35. #4 QUESTIONIF BLUE DYE WAS SPILLED ON A SHIRT,WOULD IT BE A CHEMICAL OR PHYSICALCHANGE? WHY?
  36. 36. ANSWERS:#1- Pure substances are classified into two categories,elements and compounds.#2-You would use a physical change if you wanted thecomposition of the substances to stay the same.#3-The technique used to isolate a solution of salt andwater would be evaporation.#4-It would be a chemical change if blue dye wasspilled on a shirt because it changes the color, but also,it can never come out therefore it adds to the object.

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