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Chemistry

Chemistry. Chapter 1- Matter and Measurement. What is Chemistry?. Chemistry is the science concerned with the composition, structure, and properties of matter. Matter. Physical material of the universe; it is anything that has mass and occupies space. Classified by: Physical State Gas

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Chemistry

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  1. Chemistry Chapter 1- Matter and Measurement

  2. What is Chemistry?

  3. Chemistry is the science concerned with the composition, structure, and properties of matter.

  4. Matter Physical material of the universe; it is anything that has mass and occupies space. Classified by: • Physical State • Gas • Liquid • Solid • ????? • Composition

  5. Composition • Heterogeneous – visually distinctive parts - a mixture that is not uniform in composition, properties, and appearance throughout. • Homogeneous – mixtures that are uniform throughout. • Mixture (solution)- matter that is uniform throughout and can be separated. • Pure substance - matter that has distinct properties and composition that does not vary from sample to sample and can not be separated. • Element – simplest form of matter • Compound – composed of two or more elements

  6. Matter NO YES Uniform distribution? Heterogeneous Mixture Homogenous YES NO Fixed composition Pure substance Solution/mixture Can it be broken down into Simpler substances? NO YES element compound

  7. Properties • Physical Properties – can be measured without changing the identity and composition of the substance. • Chemical Properties - describes the way a substance may change or react to form other substances. • Intensive Properties – not dependent on amount of substance and used for identification. • Extensive Properties – depend on amount of the substance.

  8. Chemical/Physical Changes • Physical changes – changes in the physical appearance of a substance. • Chemical changes – changes in the substance such that it forms a new substance. • Formation of a light • Formation of a gas • Formation of a precipitate • Change in temperature • Permanent change in color

  9. Scientific Notation A method of expressing a number as a product of a number between 1 and 10 and the appropriate power of 10. Ex. 9400 in scientific notation is 9.4 x 103 0.0000943in scientific notation is 9.43 x 10-5

  10. Multiplication of Scientific Notation Ex. (4.6 x 105) x ( 3.2 x 103) • Multiply the numbers • Add the exponents • Rewrite in correct notation (4.6 x 3.2) x 10(5+3) =14.72 x 108 =1.472 x 109

  11. Division of Scientific Notation Ex. (4.6 x 105) ÷ ( 3.2 x 103) = • Divide the numbers • Subtract the exponents • Rewrite in correct notation (4.6 / 3.2) x 10(5-3) = 1.437 x 102

  12. Uncertainty in Measurements Exact numbers – defined values • Conversion factors • Date • Time • Counting small number of objects Inexact numbers – uncertainty in numbers • All measurements

  13. Limits of Measurements Precision- is a measure of how closely individual measurements agree with one another. Accuracy- refers to how closely individual measurements agree with the correct value. Significant figures –all numbers recorded in a measurement with all numbers certain plus 1 uncertain number (the last number)

  14. Precision vs. Accuracy

  15. Rules for Significant Figures • The only numbers that can be non-significant are zeros. • Any zero at the beginning of a number is not significant. It serves only to locate the decimal. • Any zero on the right hand end of a number is only significant if followed by a decimal or on the end of a decimal number. • Any zero between numbers is significant. • Exact numbers are significant.

  16. Example • Mass of an eyelash is 0.000304 • Length of a skid mark is 123.0 • 125 gram sample of chocolate chip cookies contains 10 grams of chocolate • The volume of soda remaining in a can after a spill is 0.09020 liters • A dose of antibiotic is 0.040 cm3

  17. Adding and Subtracting Numbers Scientifically When you add or subtract numbers, you can have no more decimal places in the answer than the fewest decimal places in the numbers that are added or subtracted. Ex. • 1.345 + .27 = • 13.90 – 4.8122 = • 134.1890 + 72.1 = • 0.00459 + 0.0023 =

  18. Multiplyingand Dividing When multiplying or dividing. You can have no more significant figures in the answer than the fewest number of significant figures in any number used to multiply or divide. Ex. • 45.34 ÷ 17.1 = • (11.01)(34.2)/12.34= • (45.0)/(45.689)=

  19. Units Measurements • English system • SI units – International System of Units or Metric system

  20. Prefixes for Metric Units

  21. Ex. 1 meter (m) = 1000 millimeters (mm) 1 meter (m) = 100 centimeters (cm) 1000 meters = 1 Kilometer (km) 1000 grams (g) = 1 kilogram (kg) 1 liter (l) = 1000 milliliters (ml) 1000 milliliters = 1 liter

  22. Dimensional Analysis Conversion Factors -ratio of equivalent measurements to convert from one unit to another. Ex. 1 meter = 100 centimeters 1 inch = 2.54 centimeters 1 gallon = 4 quarts 1 meter = 1.0936 yards

  23. Using Dimensional Analysis Problem- How many meters in 3.4 cm? 3.4 cm = ? m Need a conversion factor between cm and m 3.4 cm x cf = ? m

  24. Dimensional Analysis Problem: 26.5 inches equals how many centimeters?

  25. Dimensional Analysis Problem: How many seconds are in one day?

  26. Dimensional Analysis Problem: Your car has a 5.00 liter engine. What is the size of this engine in cubic inches?

  27. Temperatures Temperature can be measured in °F, °C, and K K=the absolute or Kelvin scale Water freezes at 0°C, 32 °F, and 273 K Water boils at 100°C, 212 °F, and 373 K °C = 5/9 (°F - 32.0) °F = 9/5 (°C) + 32.0 K = °C + 273

  28. Temperature What is 65.3 °F in °C? What is 56 °C in K?

  29. Density Which is heavier a pound of lead or a pound of feathers? Weight = mass = pounds Density = mass/volume So one needs larger volume of feathers to make a pound than lead.

  30. Density • The amount of matter in a given volume of a substance.

  31. Density What is the density of a metal rod that weighs 55.64 grams and has a volume of 34 ml?

  32. Density What is the density of a metal medallion that weighs 13 grams? How do you find volume?

  33. Water Displacement Method • Used to determine the volume of an irregular shaped object.

  34. Density What is the volume of a metal medallion with a density of 34. 7 g/ml that weighs 2.5 g ?

  35. Select an equation to solve for a different unknown.

  36. Density A block of metal is 3.45 cm by 2.78 cm by 7.98 cm. If this block of metal weighs 612.0 g, what is the density of the metal?

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