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MATTER & MEASUREMENTS

MATTER & MEASUREMENTS. Learning Properties & Types of Matter Changes. Math & Metric System; Numbers Precision/Accuracy. Ch. 1 lays foundation to your study. Learning Chemistry Requires you to bring together new concepts & devel new skills Need to devel good study habits

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MATTER & MEASUREMENTS

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  1. MATTER & MEASUREMENTS Learning Properties & Types of Matter Changes Math & Metric System; Numbers Precision/Accuracy

  2. Ch. 1 lays foundation to your study Learning Chemistry Requires you to bring together new concepts & devel new skills Need to devel good study habits Don’t FALL BEHIND Focus your study Good notes Text material before class Review material before class Learn language of Chem Make use of resources

  3. S: molecules held tightly in fixed position Chem all around impacts our lives; health care, environment, our needs Other fields bio, geo, engr, arts, ag MATTER mass & vol 3 States Solid - def shape, def vol, not compressible Liquid - def vol, shape of container, not compressible Gas -vapor, not def shape/vol, highly compressible

  4. L: molecules close together in random motion G: molecules far apart, no specific arrangement, move high speed, collide w/ each other & wall Physical Change  state (s-l-g) but not composition  phy appearance What effect does incr Temp cause?

  5. NO YES NO YES Classification diagram, pg 11 g, l, s gas CH3CH2CH3 MATTER mass & vol soln Li2CO3 minerals dry cmpd AgNO3 uniform thru-out liquids HETROGENEOUS Mixture HOMOGENEOUS not diff throughout table salt NaCl ocean Variable Composition MIXTURE SOLN PURE SUBST

  6. NO YES PURE SUBST H2O ----> H2 + O2 p.table made simplier ELEMENT not broken down CMPD broken down

  7. PROPERTIES Extensive \ Intensive additive non- What examples of 2 diff subst can be combined? #1: 50 ml @ 25oC #2: 100 ml @ 50oC a. vol (add-ext) b. temp (non-int) Other examples: density, spec. heat, mass, length, melting pt, boiling pt,

  8. PHYSICAL Properties: ex: taste, color, texture, size, odor, etc. CHEMICAL Properties: ex: explosive, digestive, flammable Physical \ Chemical Changes same subst new subst mix amts new props sep phy sep chem return not return

  9. METRIC SYSTEM Dimensional Analysis/Factor Label look at the “unit labels” factor-label method 500 yd to inches? conversion factors: 1 yd = 36 in 1 yd = 3ft & 1 ft = 12 in

  10. Base Units length: meters, m mass: grams, g volume: liters, l (L) Relationship: 1 ml = 1 cm3 MassWeight Based on quantity of matter present Not affected by gravity Affected by gravitational force

  11. o angstrom; ; 10-10 A nano; n; 10-9 pico; p; 10-12 10-11 10-8 10-7 10-6 micro 10-5 10-4 10-3 m milli c centi 10-2 SMALLER: down scale, move dec. pt. left 10-1 d deci BASE: gram, meter, liter 100 = 1 g, m, l da 101 deka hecto 102 h LARGER: up scale, move dec. pt. right k kilo 103 Mega; M; 106 Giga; G; 109 Tera; T; 1012

  12. How many km is 745.26 cm? 0.0074526 1.5*106L to kL?

  13. TEMPERATURE SCALES oF = (9/5 oC) + 32 oC = 5/9(oF - 32) K = 273.15 + oC • Fahrenheit, Celsius, Kelvin FREEZING PT. BOILING PT. 212o 32o oF 0o 100o oC 273.15o K 373.15o

  14. mass per unit vol table densities, pg 17 temp depend GAS: g/L consider 2 Fe samples #1: 6 g @ 7.9 g/mL #2: 4 g @ 7.9 g/cm3 Which properties are intensive? mass or density

  15. Measurements exact number: all digit values known; definition or count dozen, 12 1 ft = 12 in 2.54 cm = 1 in inexact: uncertainty in last digit value Where do they come from?

  16. SIGNIFICANT FIGURES 5.37 cm 3 4.293g 4 1. All nonzero digits are significant 2. Zeros between nonzero digits are sig. 106 ml 3 1.02 L 3 3. Zeros to the right of the dec. pt. at the end of a number are sig. 8.00 ml 3 23.0600 km 6 4. Zeros before the 1st nonzero digit in a number are not sig. 0.002 g 1 0.060 * 10-3 mm 2 0.00000725 L 3 5.Zeros at the end of a whole number are sig. if a bar is over the zero; or decimal pt shown _ _ _ 3 500 500. 500 1 2 500 3

  17. OPERATIONS Add / Subtract Count decimal places (least) 32.5437 - 3.54 161.032 5.6 + 32.4524 29.0037 199.0844 29.00 199.1

  18. Multiply / Divide Count sig. figures 5.6 * 103 8.50 152.06 * 0.24 = 658.82353 => 660 36.4944 6.6*102 36 660 This could also be used without placing a bar over the zero

  19. ACCURACY & PRECISION Accuracy • How close data points to “true” value • 7.96 7.92 8.02 • 7.96 4.02 24.87 Accuracy • Closeness of set of collected data to the “correct” or most probable value

  20. ACCURACY & PRECISION Precision • Closeness of set of collected data among the data itself Precision • How close data points are to each other; grouped • 0.997 0.999 1.003 • 1.325 0.046 5.263

  21. Poor accuracy & precision Good precision & Poor accuracy . . . . . . . . . . Good accuracy & precision . . . . .

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