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Substance

Substance. Mixture. Element. Heterogeneous mixture. Na. Fe. O 2. Neon. Gold. Carbon. H 2. Chicken soup. Italian dressing. granite. Compound. Homogeneous mixture. NaCl. Fe 2 O 3. H 2 O. Baking soda. Sugar. Sea water. Kool Aid. Grape juice. paint. bronze.

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Substance

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  1. Substance Mixture Element Heterogeneous mixture Na Fe O2 Neon Gold Carbon H2 Chicken soup Italian dressing granite Compound Homogeneous mixture NaCl Fe2O3 H2O Baking soda Sugar Sea water Kool Aid Grape juice paint bronze Stainless steel

  2. 500 mL 25 oC 10 cm long What could it be??? Anything! EXTENSIVE PROPERTIES – depends on amount 1 g/mL Clear, colorless Odorless MP 0oC BP 100oC What could it be? We have an idea! INTENSIVE PROPERTIES – do not depend on amount PROPERTIES

  3. PHYSICAL PROPERTIES What can you observe WITHOUT CHANGING what it is? Mass Size Magnetism Volume Shape Solubility Color Temperature Odor MP, BP Malleability, ductility

  4. CHEMICAL PROPERTIES What observations can you make by CHANGING what it is? Reactivity (with another substance) Corrosability Flammability

  5. Physical Changes and Separating Mixtures What can you use to separate iron from cereal? What can you use to separate sand, salt and water? What can you use to separate sulfur, sugar, and iron filings?

  6. In each case, decide if the change is a chemical or physical change. A cup of household bleach changes the color of your socks from red to pink Water vapor in your exhaled breath condenses in the air on a cold day Plants use carbon dioxide from the air to make sugar Chocolate melts when placed in the sun

  7. A cup of household bleach changes the color of your socks from red to pink - chemical Water vapor in your exhaled breath condenses in the air on a cold day - physical Plants use carbon dioxide from the air to make sugar - chemical Chocolate melts when placed in the sun - physical

  8. UNITS OF MEASUREMENT Use SI units — based on the metric system Length Mass Time Temperature Meter, m Kilogram, kg Seconds, s Kelvin, K

  9. Conversions Commonly Used Prefixes: kilo = 1000 of something ( 1km= 1000m, kg) deci =0.1 of something (10 dm = 1m) centi = 0.01 of something (100 cm = 1m) milli = 0.001 of something (103 mm = 1m) micro = 0.000001 (106 µm = 1m) nano = 0.000000001 (109 nm = 1m) pico = 0.000000000001 (1012 pm = 1m) Refer to Conversion Chart to additional prefixes.

  10. Temperature Scales 212 ˚F 100 ˚C 373 K 100 K 180˚F 100˚C 32 ˚F 0 ˚C 273 K Fahrenheit Celsius Kelvin Boiling point of water Freezing point of water Notice that 1 kelvin degree = 1 degree Celsius

  11. Temperature Scales 100 oF 38 oC 311 K oF oC K

  12. Calculations Using Temperature • Generally require temp’s in kelvins • T (K) = t (˚C) + 273.15 • Body temp = 37 ˚C + 273 = 310 K • Liquid nitrogen = -196 ˚C + 273 = 77 K

  13. DENSITY • Density is an INTENSIVE property of matter. • does NOT depend on quantity of matter. • temperature • Contrast with EXTENSIVE • depends on quantity of matter. • mass and volume (separately). Brick Styrofoam

  14. Significant Figures: Digits in a measurement having values that are known with certainty plus one digit having a value that is estimated.

  15. Measurements that contain a greater number of significant figures are more precise than measurements that contain fewer significant figures. Always select an instrument that gives you the most significant figures. Only report as many sig figs as that instrument allows.

  16. The Rules

  17. All numbers 1-9 are significant. Zeros are sometimes significant, here's how you can tell: If a decimal point is present, starts on the Pacific side, move across until you get to a 1-9 digit, and start counting to the end If a decimal point is absent, start on the Atlantic side, move across until you get to a 1-9 digit, and start counting to the end 1.100 has 4 sig figs, 0.00540 has 3, 40.01 has 4 1005 contains 4 sig. Figs., 23,000 has 2, 1,045,090 has 6

  18. When multiplying or dividing measurements: round the answer to the same number of digits as the measurement having the fewest number of significant figures. When adding or subtracting measurements: round the answer to the same number of decimal places as the measurement having the fewest number of decimal places.

  19. Identify the LEAST PRECISE measurement. Identify the MOST PRECISE digit (place) within that measurement. Round the answer to this digit (place). Higher precision 123456.7890 Lower precision

  20. Scientific Notation 10000000000000000000000 0.00000000000000000000000000001 There has to be a better way to write those numbers Rules for scientific notation 1) Write only the sig figs. Express the number starting with the one’s place followed by any decimal digits, times a power of 10. 2)To express a large number, count the number of decimal places needed to move to the one’s place, and make that number the exponent of ten. 3) To express a very small number, count the number of decimal places needed to move to the one’s place, and make that number the NEGATIVE exponent of ten. 4) You can always check it by writing out the expanded ten, and multiply it by the measured number.

  21. Scientific Notation Examples: 0.0000000000000000000000000000000010 = 1.0 x 10-35 94140000000000000000000000000000000 = 9.414 x 1035

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