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Chemistry – Observation – Inference –

Chemistry – Observation – Inference –. Law – Theory – A law tells a theory is an attempt to. Scientific Method – a systematic and logical way to approach problem solving. Problem/observations (collect data) Hypothesis – Experiment – Conclusion –.

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Chemistry – Observation – Inference –

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  1. Chemistry – Observation – Inference –

  2. Law – Theory – A law tells a theory is an attempt to .

  3. Scientific Method – a systematic and logical way to approach problem solving • Problem/observations (collect data) • Hypothesis – • Experiment – • Conclusion –

  4. Law of Conservation of Mass/Energy –. Physical Change – Chemical Change –

  5. Signs of a Chemical Reaction • Heat or light • ____ is produced • A _____ is formed • _____ is produced or made in the reaction • A __________ is made

  6. Physical or Chemical change • Ice melting • Cooking • Placing metal wire in acid • Placing Alka Seltzer in water • Tear paper • Boiling water • Boil potato

  7. Physical Properties – Chemical Properties –

  8. Matter – Substance – Element – Compound – Mixture – Homogeneous – Heterogeneous –

  9. Classify each as an element, cmpd, homo/hetero mix Tap water aluminum air Polluted air store bought milk “whole” milk Sugar salt 14 K gold 24 K gold H2SO4 river water Salt water O.J. w/pulp ice & water Raw hamburger glass of Cherry Coke mercury Red Kool Aid cough medicine maple leaf Brass choc. chip cookie H2O2 Chunky peanut butter steel can of paint “bubble gum” medicine 1,3,5-trinitrotoluene

  10. Ways to Separate a Mixture • Separation by hand • Filtration • Evaporation • Centrifuge • Chromatography • Distillation

  11. How would you separate a mixture of: • Salt and water • Salt and sand • Water and alcohol • Clay and water • Different colors of ink • Blood

  12. Qualitative Measurement – Quantitative Measurement Accuracy – Precision – Accuracy is not the same as precision

  13. Metric Units Mass – Volume – Length –

  14. Metric Prefixes

  15. Converting with metric units • K H D __ d c m • Place 1 under starting prefix • Place 2 under ending prefix • Draw an arrow from 1 to 2. This is the direction to move the decimal point. • Count the number of places to go from 1 to 2. Be sure to count the __ space. • Move decimal point and rewrite number.

  16. Make the following metric conversions 13.5 g  kg 2.75 ml  l 150 mm  cm 0.0150 m  cm 0.195 cg  mg 0.750 l  ml 2.46 mg  kg 5.79 Hl  l 7.53 km  cm 0.0432 g  mg 4150 cl  l 739 dm  m 81.8 cg  kg 418.2 m  km

  17. Scientific Notation – a way of showing very large or small numbers. 4.7 x 103 4.7 E 3 4.7 exp 3 4.7 x 10 x 10 x 10 = 4,700 The exponent or power tells how many places the decimal point will be moved. If the exponent is positive, If the exponent is negative, The “number out front” is only allowed to have one nonzero digit to the left of the decimal point.

  18. Write each of these using scientific notation 0.000325 4270 16.2 19,500,000 0.125 485 0.0417 0.0000093 Write each of these as a “regular” number 2.75 E 2 9.13 E-4 7.38 E-1 8.05 E3 7.76 E-3 5.35 E-2 1.48 E6 6.39 E1 2.34 E-2

  19. Significant Figures (sig figs) – • Atlantic/Pacific Rule • If a decimal point is absent, count from the Atlantic (right) side starting with the first nonzero digit. • If a decimal point is present, count from the Pacific (left) side starting with the first nonzero digit • 508.0 820 0.0490 135 1000 • 1000. 1000.00 0.0300 1.30 E4 0.150

  20. Defined or exact numbers have an infinite number of significant figures. Rounding off numbers: 0-4 drop, 5-9 add 1 Rounding numbers in calculations Add/subtract: Mult./divide:

  21. When doing calculations, you round off when the following occurs: • When the rules for rounding change (going from add  divide, mult  add) • Get to the end of the problem, and you are giving the final answer.

  22. Conversions that you are responsible for knowing 12 in = 1 ft; 3 ft = 1 yd; 5280 ft = 1 mile 60 sec = 1 min; 60 min = 1 hr; 24 hr = 1 day, 7 day = 1 wk; 365.25 day = 1 yr 16 oz = 1 lb; 2000 lb = 1 ton 8 oz = 1 cup; 2 cups = 1 pint; 2 pints = 1 quart 4 quarts = 1 gallon

  23. Unit analysis/dimensional analysis/factor-label: A method of converting from 1 set of units to another set of units using a series of conversion factors. A conversion factor is 12 in = 1 ft 1 ft/12 in or 12 in/1 ft Each equivalency can produce

  24. Convert 22 inches to feet • List possible conversion factors: 12 in/1 ft 1 ft/12 in • Set up grid with starting number and units in the upper left side: • 22 inches | = feet | • Plug in conversions so that the same units are on the diagonal • 22 inches | 1 ft = 1.8 ft | 12 inches

  25. Use unit analysis: • 5.75 min  month • 135 km  cm • 17.5 oz  gal • 1.5 mile  inch • 145 mg  hg • 135 ml  l • 275 yds  meter (1.00 in ≈ 2.54 cm) • 15.8 l  gal (1.00 oz ≈ 29.5 ml)

  26. Density – a ratio of mass and volume of an object D = M/V M = D x V V = M/D Every pure substance will have its own characteristic density. This means that density can help identify a substance. Density of pure water = When two objects with different densities are mixed: The object with the larger density The object with the smaller density

  27. A pure substance has a mass of 65.3 g and a volume of 75.0 ml. What is the density of the object, and what happens when it is put in water? Mercury has a density of 13.6 g/ml. What is the volume of 745 g of mercury?

  28. Temperature – A measure of the average kinetic energy of the particles in a substance. Water boils: Water freezes: As the temperature goes up, As the temperature goes down, There is a theoretical temperature at which all motion stops: ABSOLUTE ZERO = 0 K = -273 oC = -459 oF

  29. Temperature scales oC K oF 0 273 32 100 373 212 37 310. 98.6 -273 0 -459 oC + 273 = K K – 273 = oC

  30. Types of Graphs • Pie or Circle Graph: shows % or parts of the whole • Bar Graph: comparing two unrelated variables • Line Graph: comparing two related variables. This is the most common type of graph used in chemistry.

  31. Graphing • X axis: • Y axis: • Title: Y vs X or Dependent vs Independent • Each axis should have a label • Each “box” on the axis has to be • Pick “easy numbers” to label boxes.

  32. Y axis boxes do not have to be the same value as the X axis boxes • Value of Box = Range of Values/#boxes • Data points must take up at • All points must be on the graph. • Usually draw a single straight line through points, best fit line, not “dot to dot”. • Slope = Rise/Run = ΔY/ΔX = (Y2-Y1)/(X2-X1)

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