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Significant Figures Review

Significant Figures Review. How many significant figures are in each measurement? 0.074 m b. 40.007m c. 143g Correct or Incorrect ? 37.2 + 18.45 + 380.423 = 436.073 34 / 10.1 = 3.366336634. Kilogram Prototype. kg. Metric Units. cg. mg. g.

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Significant Figures Review

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  1. Significant Figures Review • How many significant figures are in each measurement? • 0.074 m b. 40.007m c. 143g • Correct or Incorrect ? • 37.2 + 18.45 + 380.423 = 436.073 • 34 / 10.1 = 3.366336634

  2. Kilogram Prototype kg Metric Units cg mg g Mass refers to the amount of matter in an object. The base unit of mass in the metric system in the kilogram and is represented by kg. Metric Units 1 Kilogram (km) = 1000 Grams (g) 1 Gram (g) = 1000 Milligrams (mg) Click the image to watch a short video about mass. Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram

  3. Measuring Volume We will be using graduated cylinders to find the volume of liquids and other objects. Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water. What is the volume of water in the cylinder? _____mL Top Image: http://www.tea.state.tx.us/student.assessment/resources/online/2006/grade8/science/images/20graphicaa.gifBottom Image: http://morrisonlabs.com/meniscus.htm

  4. Units and Quantities 3.2 • Units of Temperature • Temperature is a measure of how hot or cold an object is. • Thermometers are used to measure temperature.

  5. Units and Quantities 3.2 • Because one degree on the Celsius scale is equivalent to one kelvin on the Kelvin scale, converting from one temperature to another is easy. You simply add or subtract 273, as shown in the following equations.

  6. Conversion Problems 3.33 • Many times throughout this class you will have to convert from one unit to another this is called dimensional analysis. • You use dimensional analysis everyday. • For example: • 1 dollar = 4 quarter=10 dimes =20 nickels=100 pennies • These are called conversion factors

  7. 3.3 Conversion Factors • A conversion factor is a expression of equivalent measurements. Expressed as a ratio • For Example: 1 meter = 100 cm • Conversion factors makes it easier to mathematically calculate problems in which a given measurement must be expressed with another unit.

  8. 3.3 Dimensional Analysis • Dimensional analysis is a way to analyze and solve problems using the units, or dimensions, of the measurements. • Dimensional analysis provides you with an alternative approach to problem solving.

  9. Example #2 Converting metrics • How many meters are in 435cm • #1 what do we know? We know that 1 m = 100 cm • #2 Start with what you are given = 435cm • 435cm 1 m • 100 cm • 3. Set up the ratio so that the correct units cancel, • Remember we must be left with meters.

  10. Pepsi puts 355 mL of pop in a can. How many drops is this? • Conversion Factor = 20 drops = 1ml

  11. 3.5

  12. 3.5 You must make sure that your ratios are set up in such a way That when you multiply or divide, units cancel until you are left With the units that correctly answer the problem

  13. 3.5

  14. 3.5

  15. CONVERSIONS K = °C + 273.15 °C = K – 273.15

  16. International System of Units (SI) • Revised version of the metric system • Based units (symbol) – quantity (non-SI unit) • meter (m) – length • kilogram (kg) – mass • kelvin (K) – temperature (°C) • second (s) – time • mole (mol) – amount of substance • candela (cd) – luminous intensity • ampere (A) – electric current

  17. Common units of volume • L = Liter • mL = milliliter • Common Units of Mass • g = grams • mg = milligrams • kg = kilograms • space occupied by any sample of matter.

  18. Temperature Scales • Celsius • Defined by the freezing and boiling points of water • Units → °C • Kelvin • Defined by absolute zero • Temperature at which all motion theoretically stops • Has the same “size” units as Celsius scale • Units → K

  19. Convert 0.048 kg of sulfur to g of sulfur • (1kg = 1000g)

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