Mastering Units of Measurement in Chemistry

1. Chapter 5 Sections 5.2-5.3 Units of Measurement Mrs. Baldessari Chemistry Objectives: Use the metric system to measure length, volume, and mass

2. MeasurementAt the conclusion of our time together, you should be able to: Explain the difference between the two types of observations Give examples of 5 basic SImeasuring units Give examples of 3 different derived units from the basic SI units Vary the amounts of the SI measuring units with 10 different prefixes and define each Explain the difference between mass and weight List and explain 5 different units for volume.

3. Measurement You are making a measurement when you • Check you weight • Read your watch • Take your temperature • Weigh a cantaloupe What kinds of measurements did you make today?

4. Some Tools for Measurement

5. Learning Check From the previous slide, state the tool (s) you would use to measure A. temperature ____________________ B. volume always use a ____________________ never use a ____________________ C. time ____________________ D. weight ____________________

6. Solution From the previous slide, state the tool (s) you would use to measure A. temperature thermometer B. volume always use a: graduated cylindernever use a: Beaker C. time stop watch D. weight scale

7. Measurement in Chemistry In chemistry we • do experiments • measure quantities • use numbers to report measurements

8. Learning Check What are some U.S. units that are used to measure each of the following? A. length B. volume C. weight D. temperature

9. Solution Some possible answers are A. length inch, foot, yard, mile B. volume cup, teaspoon, gallon, pint, quart C. weight ounce, pound (lb), ton D. temperature °F

10. Metric System (SI) • Is a decimal system based on 10 • Used in most of the world • Used by scientists and hospitals

11. Units in the Metric System • length meter m • volume liter L • mass gram g • temperatureCelsius °C

12. Stating a Measurement In every measurement there is a • Number followed by a • Unit from measuring device

13. Quantitative Measurements in Chemistry Must Include Units!

14. Learning Check What is the unit of measurement in each of the following examples? A.The patient’s temperature is 38.8 °C . B. The sack holds 2.3 kg of potatoes. C. It is 12.8 km miles from your house to school. D. The bottle holds 2 L of orange soda.

15. Solution A. °C (degrees Celcius) B. Kg (Kilograms) C. Km (Kilometers) D. L (liters)

16. Learning Check Identify the measurement in metric units. A. John’s height is 1) 1.5 yards 2) 6 feet 3) 2 meters B. The volume of saline in the IV bottle is 1) 1 liters 2) 1 quart 3) 2 pints C. The mass of a lemon is 1) 12 ounces 2) 145 grams 3) 0.6 pounds

17. Solution A. John’s height is 3) 2 meters B. The volume of saline in the IV bottle is 1) 1 liter C. The mass of a lemon is 2) 145 grams

18. Types of Observations and Measurements We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE observations that involve MEASUREMENTS with numbers and units.

19. Stating a Quantitative Measurement In every measurement there is a • Number (Quantity) followed by a • Unit or label from a measuring device • Remember: No naked numbers

20. Quantitative Measurements in Chemistry Must Include Units!

21. Standards of Quantitative Measurement For example, at one time the standard for length was the king’s foot. What are some problems with this standard? When we measure, we use a measuring tool to compare some dimension of an object to a standard.

22. Base SI Units

23. Units Of Measurement You Must Know meter, m kilogram, kg liter, L seconds, s kelvin, K Use SI units — based on the metric system Length Mass Volume Time Temperature

24. Unit for Length 1 Meter or centimeter Note: Not Foot or inches !!

25. Metric Prefixes • Kilo- means 1000 of that unit • 1 kilometer (km) = 1000 meters (m) • Centi- means 1/100 of that unit • 1 meter (m) = 100 centimeters (cm) • 1 dollar = 100 cents • Milli-means 1/1000 of that unit • 1 meter (m) = 1000 millimeters (mm)

26. Metric Prefixes You Need to Know

27. The pneumonic: King Henry Died Unexpectedly Drinking Chocolate Milk Memorize      this!

28. You must also know… …how to convert within the Metric System. Here’s a good device: On your paper draw a line and add 7 tick marks:

29. Next: Above the tick marks write the abbreviations for the King Henry pneumonic: k h d (u ) d c m m l g Write the units in the middle under the “U”.

30. Let’s add the meter line: k h d u d c m km hm dam m dm cm mm L g

31. Let’s add the liter line: k h d u d c m km hm dam m dm cm mm kL hL daL L dL cL mL g Deca can also be dk or da

32. Let’s add the gram line: k h d u d c m km hm dam m dm cm mm kl hl dal l dl cl ml kg hg dag g dg cg mg

33. How to use this device: Look at the problem. Look at the unit that has a number. On the device put your pencil on that unit. Move to new unit, counting jumps and noticing the direction of the jump. 3. Move decimal in original number the same # of spaces and in the same direction.

34. Example #1: • Look at the problem. 56 cm = _____ mm Look at the unit that has a number. 56 cm On the device put your pencil on that unit. k h d u d c m km hm dam m dm cm mm

35. Example #1: Move to new unit, counting jumps and noticing the direction of the jump! k h d u d c m km hm dam m dm cmmm One jump to the right!

36. Example #1: Move decimal in original number the same # of spaces and in the same direction. 56 cm = _____ mm 56.0. One jump to the right! Move decimal one jump to the right. Add a zero as a placeholder.

37. Example #1: 56 cm = _____ mm 56cm = 560 mm

38. Example #2: • Look at the problem. 7.25 L = ____ kL Look at the unit that has a number. 7.25 L On the device put your pencil on that unit. k h d u d c m kl hl dal L dl cl ml

39. Example #2: • Move to new unit, counting jumps and noticing the direction of the jump! k h d u d c m kl hl dal L dl cl ml Three jumps to the left!

40. Example #2: (3) Move decimal in original number the same # of spaces and in the same direction. 7.25 L = ____ kL .007.25 Three jumps to the left! Move decimal to the left three jumps. Add two zeros as placeholders.

41. Example #2: 7.25 L = ____ kL 7.25 L = .00725 kL

42. Example #3: Try this problem on your own: 45,000 g = ____mg k h d u d c m kg hg dag g dg cg mg

43. Example #3: k h d u d c m kg hg dag g dg cg mg Three jumps to the right! 45,000.000.

44. Example #3: 45,000 g = 45,000,000 mg Three jumps to the right!

45. Example #4: Try this problem on your own: 5 cm = ____ km k h d u d c m km hm dam m dm cm mm

46. Example #4: k h d u d c m km hm dam m dm cm mm Five jumps to the left! .00005.

47. Example #4: 5 cm = .00005 km Five jumps to the left!

48. Examples #5-9: Solve these five problems on your own. Show your answers to your teacher. You may choose to use the King Henry Notes. You may choose the King Henry Staircase. You may also choose to make a King Henry Slider.

49. Examples #5-9: (5) 35 mm = ____ cm (6) 14,443 L = ____ kL (7) 0.00056 kg = ____ g (8)35.4 L = ____ mL (9)16 mm = ____ km

50. One last caution: Be careful NOT to count the spot you start from, where you put your pencil point. Only count the jumps!