1. Measurement
&
Problem Solving

2. Scientific Method
The scientific method is a logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data.

3. I. Qualitative vs. Quantitative Measurements

4. Qualitative Measurement
1). Qualitative measurement = a measurement that gives descriptive, NONnumeric results a) Ex: Jillian ran a fast race. b) Ex: The light was green

5. Quantitative Measurement
2) Quantitative measurement = a measurement that gives results in definite form, usually in numbers and units a) Ex: Jeff finished his race in 54.3 seconds b) Ex: the light had a wavelength of 505 nanometers.

6. Variables
Independent variables
Dependent variables
Control variables

7. II. “SI” System

8. 1) SI System = a modernized form of the metric system used by scientists

9. A. Fundamental SI Units
1) Fundamental unit = a unit that is defined by a single standard of measurement

10. Fundamental SI Units (There are seven fundamental SI units)

11. A. Fundamental SI Units
3) Length = a measure of linear distance; the fundamental SI unit of length is the meter (m) a) The distance light travels in a vacuum during a time interval of 1/ of a second is the SI standard for one meter

12. A. Fundamental SI Units
4) Mass = a measure of the quantity of matter in a sample; the fundamental SI unit of mass is the kilogram (kg); the abbreviation for gram is “g” a) A platinum-iridium cylinder kept at the International Bureau of Weights and Measures in the French town of Sevres is the SI standard for one kilogram

13. A. Fundamental SI Units
b) Weight = a measure of the gravitational pull on matter

14. A. Fundamental SI Units
5) Time = a measure of the interval between occurrences; the fundamental SI unit of time is the second (s) a) The duration of 9,192,631,770 periods of particular radiation emitted by cesium-133 atoms is the SI standard for one second.

15. B. Derived Unit
1) Derived unit = a unit that can be obtained from combinations of fundamental units

16. Examples of Derived SI Units

17. B. Derived Unit
3) Volume = a measure of the amount of space occupied by a sample of matter; the derived SI unit of volume is the cubic meter (m3) a) Chemists often use a non-SI unit for volume, the liter (L) b) 1 dm3 = 1 L c) 1 cm3 = 1mL

18. C. Prefixes
1) Other SI units are obtained by combining prefixes with a root unit. The prefixes represent multiples or fractions of 10. The following table lists some prefixes:

19. Prefixes Used with SI Units

20. D. Prefixes Used with SI Units

21. Write the correct abbreviation for each of the following units.
Kilosecond ______________
Hectogram ______________
Dekaliter _______________
Deciliter ______________
Centimeter _______________
Milligram ______________ ks hg
daL dL cm mg

22. E. Conversions (Ladder Method)

23. Try these conversions, using the ladder method
1000 mg = ___________ g
160 cm = ____________ mm
109 g = _____________ kg
1 L = _____________ mL
14 km = _____________ m
250 m = ______________ km
1.0
1,600
0.109
1,000
14,000
0.250

24. F. Other Useful Conversions
Some English System Conversions (exact conversions):
1 foot (ft) = 12 inches (in) pound (lb) = 16 ounces (oz)
1 yard (yd) = 3 feet (ft) ton = 2000 pounds (lb)
1 mile (mi) = 5280 feet (ft)
1 quart (qt) = 32 fluid ounces (fl oz)
1 quart (qt) = 2 pints (pt)
1 gallon (gal) = 4 quarts (qt)

25. 2) Some conversions between systems: 1 inch (in) = 2
2) Some conversions between systems: 1 inch (in) = 2.54 centimeters (cm) 1 pound (lb) = grams (g) 1 gallon (gal) = liters (L)

26. III. Scientific Notation

27. 4.6 x 103 m =
4.6 m x 10 x 10 x 10 =
4600 m

28. 2) 5.4 x 10-3 m = 5.4 m ÷ 10 ÷ 10 ÷ 10 = m

29. 3) For numbers expressed in scientific notation, the decimal place goes after the first nonzero digit.

30. 4) Write each of the following numbers in scientific notation.
3.47 x 10-4 g
g = ________________
289,302 km = ________________
mm = _______________
x 105 km
4.477 x 10-5 mm

31. 5) Write each of the following numbers in ordinary notation.
8.95 x 104 m = _________________
4.796 x 10-5 hm = _______________
2.73 x 105 cm = _________________ hm
273,000 cm

32. Significant Figures

33. IV. Taking Measurements

34. 1) Review the proper way to measure using a ruler, graduated cylinder, thermometer, etc.

35. IV. Taking Measurements
Meniscus = the curvature of a liquid in a container because of surface tension.
Your eye should be level with the top of the liquid and you should read the bottom of the meniscus.

36. V. Precision, Accuracy and Percent Error:
Precision = a measure of how close a series of measurements are to one another
a) It takes a series of measurements to determine precision

37. V. Precision, Accuracy and Percent Error:
2) Accuracy = a measure of how close a measurement comes to the true or accepted value of what is measured

38. 3) Bull’s Eye Analogy

39. V. Precision, Accuracy and Percent Error:
4) Percent error = the difference between the measured quantity and the accepted value, expressed as a percentage of the accepted value

40. Percent Error Formula:
Value accepted - Valueexperimental
% error = Value accepted x 100
5) Gary measured the density of a piece of lead to be g/cm3. The accepted value for the density of lead is g/cm3. Calculate the percent error.

41. VI. Problem Solving Approach to solving problems a) Analyze:
1) Read the problem carefully at least twice.
2) Identify what you know and what you are trying to find.
3) Include units.

42. VI. Problem Solving
b) Plan: 1) Graphs, pictures, graphic organizers, flowcharts, or other visual aids may be helpful. 2) Identify formulas and/or conversion factors that will be used. 3) Be certain that “units will cancel” as needed. 4) Solve formulas for an unknown variable before putting in values. 5) Set-up the problem

43. VI. Problem Solving
c) Compute: 1) Plug in given information, conversion factors, and other necessary values. Include units on all numbers!! 2) Cancel units properly. 3) Calculate the answer.

44. VI. Problem Solving
d) Evaluate: 1) Is the answer reasonable? 2) Is the same answer obtained after rechecking? 3) Do the units cancel correctly so the answer has the proper units? 4) Have all parts of the question be answered?

45. Neither, they both weigh a pound!!!
VII. Density:
What is heavier, a pound of lead or a pound of cork?
Neither, they both weigh a pound!!!
Lead is MORE DENSE

46. Cork floats in water because it is LESS dense than water
VII. Density:
2) What floats in water, lead or cork? Why?
Cork floats in water because it is LESS dense than water

47. VII. Density:
Take a look at the two boxes below. Each box has the same volume. If each ball has the same mass, which box would weigh more? Why?

48. VII. Density:
The box that has more balls has more mass per unit of volume.
This property of matter is called DENSITY.

49. VII. Density:
4) Density = a property of matter representing the mass per unit volume. a) The derived SI unit of density: kg/m3 b) Other commonly used density units, g/cm3, g/mL, g/L

50. VII. Density:
c) Volumes can change with temperature, therefore, densities also change with temperature. Ex: Increasing the temperature of a gas would also increase the volume of the gas. Therefore the temperature of the gas, affects the density of the gas!

51. VII. Density:
d) Formula: Density = Mass__ Volume Or D = M V

52. VII. Density:
5) Solve the density formula for mass.

53. VII. Density:
6) Solve the density formula for volume.

54. 7) A sample of aluminum metal has a mass of 8. 4g
7) A sample of aluminum metal has a mass of 8.4g. The volume of the sample is 3.1cm3. Calculate the density of aluminum.

55. 8) Diamond has a density of 3. 26 g/cm3. What is the mass of a 0
8) Diamond has a density of 3.26 g/cm3. What is the mass of a cm3 of diamond?

56. 9) Suppose a scientist collects 76. 2g of mercury
9) Suppose a scientist collects 76.2g of mercury. Calculate the volume given that the density of mercury is 13.6 g/mL.