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Chapter 2 “ Matter and Change” p. 38

Chapter 2 “ Matter and Change” p. 38. Properties: Extensive – depends on amt of matter in sample - ex’s. mass, volume, calories, magnetism Intensive – depends on type of matter, not amt. Hardness, Density, B.P.

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Chapter 2 “ Matter and Change” p. 38

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  1. Chapter 2“Matter and Change”p. 38

  2. Properties: • Extensive – depends on amt of matter in sample - ex’s. mass, volume, calories, magnetism • Intensive – depends on type of matter, not amt. • Hardness, Density, B.P. • All samples of same substance have same intensive prop’s. (same composition) Describing Matter

  3. Physical Properties- observed & measured w/o changing composition • color, hardness, m.p., b.p. • Chemical Properties- observed by changing comp of material • ability to burn, decompose, ferment, react w/, etc. Identifying Substances

  4. Solid- cannot flow (definite shape & volume) • Liquid- definite vol - takes shape of container (flows) • Gas- w/o definite vol or shape & flows • Vapor- gaseous but normally liquid or solid @ room temp • water “gas”, or water “vapor”? States of matter

  5. Three Main Phases – page 41

  6. States of Matter Result of aTemperature Increase? Definite Volume? Definite Shape? Will it Compress? Small Expans. Solid YES YES Not easily Small Expans. Not easily Liquid NO YES Large Expans. Gas NO NO YES

  7. 4th state:Plasma - formed at hi temps; ionized phase of matter (Sun)

  8. Condense Freeze Evaporate Melt Sublime Gas Liquid Solid

  9. Physical changechanges visible appearance w/o changing comp of material • Boil, melt, cut, bend, split, crack • Is boiled water still water? • Reversible, or irreversible • Chemical change - change where new substance formed • Rust, burn, decompose, ferment Physical vs. Chemical Change

  10. Mixture - physical blend of 2+ components • Heterogeneous – uniform in comp • Choc chip cookie, gravel, soil • Homogeneous - same comp thruout (solutions) • Kool-aid, air, salt water • Every part keeps own prop’s Section 2.2 Mixturesp. 44

  11. Mixed molecule by molecule, so too small to see diff pts • occurs btwn any state of matter: gas-gas; liquid-gas; gas-liquid; solid-liquid; solid-solid (alloys) • Steel (Fe, Cr & Ni) Solutions - homogeneous mixtures

  12. “phase” describes any pt of sample w/ uniform comp of properties • A homogeneous mixture consists of a single phase • A heterogeneous mixture consists of two or more phases. • Note Figure 2.6, page 45 Phase?

  13. Some by physical means: rocks & marbles, iron filings & sulfur (magnet) • Differences in physical props used to separate mixtures • Filtration - separates solid from liquid in hetero mix. (by size) – Figure 2.7, page 46 Separating Mixtures

  14. Distillation:takes advantage of different boiling pts. NaCl boils at 1415 oC H2O boils at 100 oC Mg boils at 1107 oC Separation of a Mixture

  15. Components of dyes such as ink may be separated bypaper chromatography. Forensic Ink Analysis Separation of a Mixture Chromatography video

  16. 2 Greek words: • chroma "color" and “graphein "to write" • Biological labs: • ID amino acids • detects drugs in urine • Environmental labs: • ID contaminants in waste oil • pesticides in groundwater • test drinking water & test air quality • Pharmaceutical companies • prepare quantities of extremely pure materials. • Food industry • ID contaminants like aflatoxin • naturally occurring toxin produced by fungus Applications of Chromatography

  17. Substances are either: a) elements, or b) compounds Sec 2.3 Elements & Compounds p. 48

  18. Compounds v.s. Mixtures

  19. Element Compound Mixture Which is it?

  20. A “chemical change” chg producing matter w/ diff. comp than original matter 1+ substances are converted into different substances. Heat & light often indicate chem chg Chemical Change

  21. Classification of Matter

  22. 118 elements • 1 - 2 letter symbol • 1st letter CAP; 2nd letter lowercase • B, Ba, C, Ca • Some names Latin • Table 2.2, page 52 • cmpds have formula • H2O, NaCl, C12H22O11 Symbols & Formulas

  23. Chemical property - ability of substance to undergo specific chem change • Fe + O = rust • rusting - chem prop of Fe • During chem chge comp of matter always changes Sec 2.4 Chemical Rxns p. 53 Chemical Changes

  24. When 1+ substances changed into new substances • Reactants- start w/ • Products- end w/ • Products have NEW PROPS diff from reactants • Arrow points from reactants to new products Chemical Rxns are…

  25. Energy absorbed/released (temp changes hotter/colder) • Color changes • Gas production (bubbling, fizzing, or odor change; smoke) • precipitateforms - solid separates from solution (won’t dissolve) • Irreversibility- not easily reversed Some ex’s not chem – boiling water bubbles, choc syrup in milk, etc. Recognizing Chemical Changes

  26. During any chem rxn, product mass = reactant mass • All mass accounted for: • Burning wood results in products that appear to have less mass (ashes)…. • CO2 & H2O vapor • Law of conservation of mass Conservation of Mass

  27. - Page 55 43.43 g Original mass = 43.43 g Final mass reactants = product

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