2. Chemistry "Only those who have the patience to do simple things perfectly will acquire the skill to do difficult things easily." -- Johann von Schiller

3. II. Measurement QQuantitative observations are the most powerful form of scientific information. HHow do we express quantitatively what we observe? WWe take measurements to represent a quantity. EExample: AA chef wrote a recipe for a cake as 1 salt, 3 sugar, 2 flour & ½ water WWhat’s the problem? Measurements – must include a number plus a unit. 1 teaspoon salt, 3 tablespoons sugar, 2 cups flour & ½ cup water. The choice of unit will depend on the quantity of what is being measured

5. History  At the end of the 18 th century in France, scientists created the metric system.  It was designed with several features in mind.  1. that each type of measurement (mass, volume, and length) would only have one unit; for example, length would be measured in meters instead of in feet, inches, rods, ells, hands, or any other specialized measures that may or may not be easy to convert between  2. the metric system would be based on units of 10 for easy conversions

6. Who uses the Metric System?  SCIENTISTS (and science students)  Almost every country EXCEPT the United States.  The US uses the English unit of measurement which is based on the lengths, weights, areas and volumes of everyday objects.  Using the same system of measurement gives scientists a common language.   In 1960 at the International Convention, the metric system was adopted as the “International system of Units” or SI.   SI is based on units of ten.

7. Metric Prefixes  Metric Units  The metric system has prefix modifiers that are multiples of 10.  1 L = 1000 mL1km = 1000 m1 mg =.001 g PrefixSymbolFactor NumberFactor Word Kilo-k1000Thousand Hecto-h100Hundred Deca-da or dk10Ten Unitm, l, or g1One Deci-d.1Tenth Centi-c.01Hundredth Milli-m.001thousandth

8. Place Values of Metric Prefixes Thousand Hundred Ten One Tenth Hundredth Thousandth km kg kL hm hg hL dkm dkg dkL mgLmgL dm dg dL cm cg cL mm mg mL

9. Common Prefixes  Mnemonics is a helpful way to remember the order of common prefixes.  K-h-Da-M-d-c-m use this one or create your own.

10. Practice  1 km = _____________ m  1 g = _____________cg  1 mL = _______________ L

11. Scientific Measurement  Collecting data often requires measurement…What can you measure?  Length (distance)  Volume  Mass (weight)  Temperature  Time

12. Length  The basic unit of length in the metric system is the meter (m)  The meter is = to 39.4 inches

13. Meters  Meters measure length or distance  One millimeter is about the thickness of a dime.

14. Meters  One centimeter is about the width of a large paper clip or your fingernail.

15. Meters  A meter is about the width of a doorway

16. Meters  A kilometer is about six city blocks or 10 football fields.  1.6 kilometers is about 1 mile

17. Mass  Mass is a measure of the amount of matter contained in an object.  Your weight on another planet may differ due to the amount of gravity, however your mass will always be the same  Metric unit for mass is the gram

18. Gram  Grams are used to measure mass or the weight of an object.

19. Grams  A milligram has the same mass as a grain of salt.

20. Grams  1 gram has the same mass as a small paper clip.  1 kilogram has about as much mass as 6 apples or 2 pounds.

21. Volume  Volume is the amount of space an object takes up.  The basic unit of volume is the liter (L)  The liter is usually used for measuring the volume of liquids  The volume of solids can be measured in cubic centimeters (cc or cm 3 ) = a cube that measures 1cm x 1cm x 1cm  1cc is exactly equal to in volume to 1 ml (1 cc= 1ml)

22. Liters  Liters measure liquids or capacity.

23. Liter  1 milliliter is about the amount of one drop

24. Liter  1 liter is half of a 2 liter bottle of Coke or other soda

25. Liter  A kiloliter would be about 500 2-liter bottles of pop

27. Which unit would you use to measure the length of this bicycle? kmmcmmm

28. Which unit would you use to measure the mass of a penny? kmgcLmg

29. Which unit would you use to measure the water in an aquarium? LmcLmg

30. Which unit would you use to measure the mass of a feather? LmcLmg

31. Which unit would you use to measure the mass of a student desk? kggcLmg

32. Which unit would you use to measure a can of soup? kLLmmmL

33. Which unit would you use to measure the distance across Kansas? kmmcmmL

34. IV. Scientific Notation

35. Why is it that we use scientific notation in science? BBecause many of the numbers, amounts, etc. that we use are either really big or very small. Distance from Earth to Sun 150,000,000,000 m Average size of atom 0.0000000000000015 m

36. Overview of Scientific Notation 4.4 x 10 -4 This number is called the base. IT MUST BE GREATER THAN ONE (1) AND LESS THAN TEN (10)!!!! The exponent tells you have many spaces you will need to move the decimal to get to the number in long form

37. Rules for Scientific Notation EX: 18000 = 1.8 x 10 4 For a large number: Put the decimal point after the first non-zero number then count spaces to the end EX: 0.00044 = 4.4 x 10 -4 For a small number: Put the decimal point after the first non-zero number then count spaces to the original decimal place  If the number is large – you will have a positive exponent  If the number is very small – you will have a negative exponent.  Exponent decides which direction and how many spots you will move the decimal

38. Examples  What is the correct scientific notation for:  25000.00000801 12.87  What is the correct standard notation for:  1.98 x 10 3  2.609 x 10 -2  3.81 x 10 -5  0.070 x 10 5  0.005 x 10 -3 2.5 x 10 4 8.01 x 10 -6 1.287 x 10 1 1980 (3 sig fig) 0.02609 (4 sig fig) 0.0000381 (3 sig fig) 7000 (2 sig fig) 0.000005 (1 sig fig)

39. Calculations with Scientific Notation The EE button EE means “x10” Use this button to enter a negative number Most calculators have a key on them for doing scientific notation. We will be using the EE/EXP/ x 10 n Button. Do NOT use the "hat" symbol on your calculator to enter scientific notation (eg. 4.5 x 10^5). Your calculator will treat this as two separate numbers, and you will get some calculations wrong. Do NOT enter x10… the EE button does that for you! Directions: Enter #... Press EE… Enter exponent #

40. Multiplication/Division Examples: *get calculator answer… put in scientific notation…  (2 x 10 2 )x (3 x 10 4 ) = 6,000,000  (6 x 10 10 ) ÷ (3 x 10 8 ) = 200  (4 x 10 3 ) x (9 x 10 5 ) = 3,600,000,000  (4 x 10 1 ) ÷ (2 x 10 2 ) = 0.2 6 x 10 6 2 x 10 2 4 x 10 9 2 x 10 -1 *If needed, round to the tenths place!

41.  Addition Example:  (2.456 x 10 5 ) + (6.003 x 10 8 ) =  Subtraction Example:  (1.4 x 10 -5 ) - (5.67 x 10 -6 ) =  0.00000833 = 8.3 x 10 -6  600545600 = 6.005 x 10 8 *Round your answer to the tenths place! Addition/Subtraction Examples: *get calculator answer… put in scientific notation… then correct number of decimal places

42. Practice:  (2.68 x 10 -5 ) x (4.40 x 10 -8 ) = 1.17928 x 10 -12  (2.95 x 10 7 ) ÷ (6.28 x 10 15 ) = 4.69745 x 10 -9  (8.41 x 10 6 ) x (5.02 x 10 12 ) = 4.22182 x 10 19  (9.21 x 10 -4 ) ÷ (7.60 x 10 5 ) = 1.2118421 x 10 -9  (4.52 x 10 -5 ) + (1.24 x 10 -2 ) = 0.0124452  1.18 x 10 -12  4.70 x 10 -9  4.22 x 10 19  1.21 x 10 -9  1.24 x 10 -2

43. How can you decide if your experiments are accurate/precise?  Percent error = calculations that will give you a percent deviation from the true value.  Formula: l True – experimental l x 100 True IV. Percent Error

44.  A student measured the density of an object to be 2.889 g/ml, the true density of the object is 2.699g/ml. What is the percent error of the experiment? Is the student accurate?  l 2.699 g/ml – 2.889 g/ml l x 100 2.699 g/ml  ANSWER: 7.040% error, anything below 10% is acceptable as accurate. The closer to 0% the better! IV. Percent Error

45.  MAKE SURE THAT YOU ESTIMATE THE DATA BEFORE DOING THE ACTIVITY!  There are six stations:  Paper Plate Discus  Plastic Straw Javelin  Cotton Ball Shot Put  Right-handed Marble Grab  Left-handed Sponge Squeeze  Big Foot Contest  The team with the LEAST AMOUNT OF % ERROR WINS!

46. DIMENSIONAL ANALYSIS

47. What is Dimensional Analysis?  Have you ever used a map?  Since the map is a small-scale representation of a large area, there is a scale that you can use to convert from small-scale units to large- scale units—for example, going from inches to miles or from cm to km.

48. What is Dimensional Analysis? Ex: 3 cm = 50 km

49. What is Dimensional Analysis?  Have you ever been to a foreign country?  One of the most important things to do when visiting another country is to exchange currency.  For example, one United States dollar equals 1535.10 Lebanese Pounds.

50. What is Dimensional Analysis?  Whenever you use a map or exchange currency, you are utilizing the scientific method of dimensional analysis.

51. What is Dimensional Analysis?  Dimensional analysis is a problem-solving method that uses the idea that any number or expression can be multiplied by one without changing its value.  It is used to convert from one unit to another.

52. How Does Dimensional Analysis Work?  A conversion factor, or a fraction that is equal to one, is used, along with what you’re given, to determine what the new unit will be.

54. How Does Dimensional Analysis Work?  A conversion factor, or a fraction that is equal to one, is used, along with what you’re given, to determine what the new unit will be.

55. How Does Dimensional Analysis Work?  In our previous discussions, you could say that 3 cm equals 50 km on the map or that $1 equals 1535.10 Lebanese Pounds (LBP).

56. How Does Dimensional Analysis Work?  If we write these expressions mathematically, they would look like 3 cm = 50 km $1 = 1535.10 LBP

57. Examples of Conversions  60 s = 1 min  60 min = 1 h  24 h = 1 day

58. Conversion Factors 1 inch = 2.54 cm 1 gallon = 3.78 L 1 cm 3 = 1 mL 1 lb = 16 oz 1.06 quarts = 1 L 1 mile = 5280 ft 1 ft = 12 inch 1 lb = 454 g

59. Examples of Conversions  You can write any conversion as a fraction.  Be careful how you write that fraction.  For example, you can write 60 s = 1 min as 60s or 1 min 1 min 60 s

60. Examples of Conversions  Again, just be careful how you write the fraction.  The fraction must be written so that like units cancel.

61. Steps 1. Start with the given value. 2. Write the multiplication symbol. 3. Choose the appropriate conversion factor. 4. The problem is solved by multiplying the given data & their units by the appropriate unit factors so that the desired units remain. 5. Remember, cancel like units. 6. Multiply everything in the numerator (above the fraction line) and divide by everything in the denominator (below the fraction line).

62. Let’s try some examples together… 1. Suppose there are 12 slices of pizza in one pizza. How many slices are in 7 pizzas? Given: 7 pizzas Want/unknown: # of slices Conversion: 12 slices = one pizza

63. 7 pizzas 1 Solution  Check your work… X 12 slices 1 pizza = 84 slices

64. Let’s try some examples together… 2. How old are you in days? Given: 17 years Want: # of days Conversion: 365 days = one year

65. Solution  Check your work… 17 years 1 X 365 days 1 year = 6052 days

66. Let’s try some examples together… 3. There are 2.54 cm in one inch. How many inches are in 17.3 cm? Given: 17.3 cm Want: # of inches Conversion: 2.54 cm = one inch

67. Solution  Check your work… 17.3 cm 1 X 1 inch 2.54 cm = 6.81 inches Be careful!!! The fraction bar means divide.

68. Now, you try… 1. Determine the number of eggs in 23 dozen eggs. 1. If one package of gum has 10 pieces, how many pieces are in 0.023 packages of gum?

69. Multiple-Step Problems  Most problems are not simple one-step solutions. Sometimes, you will have to perform multiple conversions.  Example: How old are you in hours? Given: 17 years Want: # of hours Conversion #1: 365 days = one year Conversion #2: 24 hours = one day

70. Solution  Check your work… 17 years 1 X 365 days 1 year X 24 hours 1 day = 148,920 hours

71.  EX: Convert 800.0 grams into pounds  800.0g ( 1lb ) = 1.762 lb 1 ( 454g ) *gram unit in denominator so it cancels out leaving only the unit of pound.

72. Convert  25.0 inches → cm  2.45 pounds → grams  2500 grams → pounds  500.0 cm → inches 25.0 in 2.54 cm _= 63.5 cm (3sf) 1 1 in 2500 g 1 lb ___= 5.50660793 = 5.5 lb (2sf) 1 454 g 500.0 cm 1 in ___= 196.85039 = 196.9 in (4sf) 1 2.54 cm 2.45 lb 454 g ___= 1112.3 = 1110 g (3sf) 1 1 lb

73. Convert  750 cm → feet  27000 cm → miles  35 oz → grams  7.5 gallons → liters 750 cm 1 in ___ 1 ft = 24.606299 = 25 feet (2sf) 1 2.54 cm 12 in 27000 cm 1 in ___ 1 ft 1 mile= 0.1677 = 0.17 miles (2sf) 1 2.54 cm 12 in 5280 ft 35 oz 1 lb ___ 454 g = 993.125 = 990 g (2sf) 1 16 oz 1 lb 7.5 gal 3.78 L = 28.35 = 28 L (2sf) 1 1 gal