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Slide 1 of 33 International System of Units 3.2. © Copyright Pearson Prentice Hall Slide 2 of 33 3.2 The International System of Units In the signs shown.

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Presentation on theme: "Slide 1 of 33 International System of Units 3.2. © Copyright Pearson Prentice Hall Slide 2 of 33 3.2 The International System of Units In the signs shown."— Presentation transcript:

1 Slide 1 of 33 International System of Units 3.2

2 © Copyright Pearson Prentice Hall Slide 2 of 33 3.2 The International System of Units In the signs shown here, the distances are listed as numbers with no units attached. Without the units, it is impossible to communicate the measurement to others. When you make a measurement, you must assign the correct units to the numerical value.

3 Slide 3 of 33 © Copyright Pearson Prentice Hall The International System of Units > Measuring with SI Units Which five SI base units do chemists commonly use? 3.2

4 Slide 4 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Measuring with SI Units All measurements depend on units that serve as reference standards. The standards of measurement used in science are those of the metric system. The International System of Units (abbreviated SI, after the French name, Le Système International d’Unités) is a revised version of the metric system. There are 7 base units.

5 Slide 5 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Measuring with SI Units The five SI base units commonly used by chemists are the meter, the kilogram, the kelvin, the second, and the mole. See page 73.

6 Slide 6 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Units of Length In SI, the basic unit of length, or linear measure, is the meter (m). For very large or and very small lengths, it may be more convenient to use a unit of length that has a prefix. See page 74. Memorize!!

7 Slide 7 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Common metric units of length include the centimeter, meter, and kilometer.

8 Slide 8 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Units of Volume The SI unit of volume is the amount of space occupied by a cube that is 1 m along each edge. This volume is the cubic meter (m) 3. A more convenient unit of volume for everyday use is the liter, a non-SI unit. A liter (L) is the volume of a cube that is 10 centimeters (10 cm) along each edge (10 cm  10 cm  10 cm = 1000 cm 3 = 1 L).

9 Slide 9 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Common metric units of volume include the liter, milliliter, cubic centimeter, and microliter.

10 Slide 10 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities The volume of 20 drops of liquid from a medicine dropper is approximately 1 mL.

11 Slide 11 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities A sugar cube has a volume of 1 cm 3. 1 mL is the same as 1 cm 3.

12 Slide 12 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities A gallon of milk has about twice the volume of a 2-L bottle of soda.

13 Slide 13 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Units of Mass The mass of an object is measured in comparison to a standard mass of 1 kilogram (kg), which is the basic SI unit of mass. A gram (g) is 1/1000 of a kilogram; the mass of 1 cm 3 of water at 4°C is 1 g.

14 Slide 14 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Common metric units of mass include kilogram, gram, milligram, and microgram.

15 Slide 15 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Weight is a force that measures the pull on a given mass by gravity. The astronaut shown on the surface of the moon weighs one sixth of what he weighs on Earth.

16 Slide 16 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Units of Temperature Temperature is a measure of the average kinetic energy of an object (or how hot or cold an object is.) Thermometers are used to measure temperature.

17 Slide 17 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Scientists commonly use two equivalent units of temperature, the degree Celsius and the kelvin.

18 Slide 18 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities On the Celsius scale, the freezing point of water is 0°C and the boiling point is 100°C. On the Kelvin scale, the freezing point of water is 273.15 kelvins (K), and the boiling point is 373.15 K. The zero point on the Kelvin scale, 0 K, or absolute zero, is equal to  273.15 °C.

19 Slide 19 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Use the following equations to convert.. K = ˚C + 273.15 ˚C = K – 273.15

20 Slide 20 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Conversions Between the Celsius and Kelvin Scales

21 © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 21 of 33 3.4 Write your answer down.

22 © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 22 of 33 3.4

23 © Copyright Pearson Prentice Hall Slide 23 of 33 Practice Problems for Sample Problem 3.4 Write your answer down.

24 Slide 24 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities Units of Energy Energy is the capacity to do work or to produce heat. The joule and the calorie are common units of energy.

25 Slide 25 of 33 © Copyright Pearson Prentice Hall The International System of Units > 3.2 Units and Quantities The joule (J) is the SI unit of energy. One calorie (cal) is the quantity of heat that raises the temperature of 1 g of pure water by 1°C.

26 © Copyright Pearson Prentice Hall Slide 26 of 33 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 3.2 Section Quiz. 3.2.

27 © Copyright Pearson Prentice Hall Slide 27 of 33 3.2 Section Quiz. 1. Which of the following is not a base SI unit? a.meter b.gram c.second d.mole

28 © Copyright Pearson Prentice Hall Slide 28 of 33 3.2 Section Quiz. 2. If you measured both the mass and weight of an object on Earth and on the moon, you would find that a.both the mass and the weight do not change. b.both the mass and the weight change. c.the mass remains the same, but the weight changes. d.the mass changes, but the weight remains the same.

29 © Copyright Pearson Prentice Hall Slide 29 of 33 3.2 Section Quiz. 3. A temperature of 30 degrees Celsius is equivalent to a.303 K. b.300 K. c.243 K. d.247 K.

30 END OF SHOW


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