1. Honors Chemistry
Measurement

2. Alchemy

3. How do you picture a chemist?

4. What is chemistry?
Chemistry is the study of all things and the changes they can undergo.
Chemistry is called a central science because it overlaps so many sciences.
Chemical – is any substance with a definite composition.

5. Chemists use the scientific method as a systematic approach to gather knowledge.
Observation
Question
Hypothesis
Experiment
Conclusion
All hypotheses must be testable in order to be a valid hypothesis.

6. Types of Observations
Qualitative: Describes something using the 5 senses
Quantitative: Uses numbers in the description
Quantity – something that has magnitude, size, or amount.
Unit – a quantity adopted as a standard of measurement

7. Experiment
Natural Law – Describes how nature behaves
Theory – Explains why nature behaves the way it does
A theory and a hypothesis are both explanations, but a theory is an explanation formed after much experimentation.

8. Variables in a Experiment
Independent Variable - You control
Dependent Variable – Variable factor – what is being tested
Experimental Control – Factor that remains constant for comparison

9. Factors in an Experiment
Independent: most regular variable – goes on the X-axis
Dependent: what you are testing – goes on the Y-axis
Experimental Control: part of the experiment that stays
the same.
Dependent variable
“Y” axis
Independent variable
“X” axis

10. Measurement in Chemistry
Measurement is a key ingredient in ALL sciences, especially chemistry.
Scientific Notation
Accuracy and Precision
Significant Figures
Measurement Devices
Metric System
Dimensional Analysis

11. Scientific Notation is a shorthand way of expressing a number
Scientific Notation is a shorthand way of expressing a number. Consists of two factors:
Coefficient - a number between 1 and 10 (only 1 digit to the LEFT of the decimal point)
Base - a power of 10  “power of 10” shows the number of 10’s that are to be multiplied together
Examples on the number line:
1x102 4x101 1x100
1x x10-1

12. Small
Numbers
Negative
Numbers
Large
Numbers
1x10-10
1x10-1
1x102
4x101
1x100

13. Adding and Subtracting (without calculator)
Exponents must be the same
If number gets bigger, exponent gets smaller
If number gets smaller, exponent gets larger
(8 x 10-2) + (3 x 10-4) - (2 x 10-3)
(80 x 10-3) + (0.3 x 10-3) – (2 x 10-3) =
78.3 x 10-3 = 7.83 x 10-2

14. Multiplication (without calculator)
Multiply number and add exponents (base 10 remains the same)
(6 x 10-6)(8 x 103) =
48 x 10-3  4.8 x 10-2
(6 x 10-3)2 =
36 x 10-6 = 3.6 x 10-5

15. Division (without calculator)
Divide number and subtract exponents (base 10 remains the same)
(7.2 x 10-8)÷(8 x 10-5) =
0.9 x 10-3  9 x 10-4

16. Cube Root
Make number a whole number, take cube root of number, multiply exponent by 1/3.
(2.7 x 10-8)1/3 =
(27 x 10-9)1/3 =
3 x 10-3

17. Square Root
Make number a whole number, take square root of number, multiply exponent by ½.
(1.44 x 10-6)1/2 =
(144 x 10-8)1/2 =
12 x = 1.2 x 10-3

18. 1st Commandment of Chemistry: KNOW THY CALCULATOR!
Find the “EE” key – it may be a 2nd function!
If you have a graphing calculator look for the following keys:
Find the (-) key.

19. Look at the calculator that is similar to yours…
Find the “Exp” or “x10x”
1st Law of Chemistry:
Know Thy Calculator!
Look at the calculator that is similar to yours…
Find the “(-)” or the “+/-” key.

20. Uncertainty in Measurement
Measurements are uncertain because:
1) Instruments are not free from error.
2) Measuring involves some estimation.
Precision –when the instrument gives you about the same results under similar conditions. The smaller the increments of measurement an instrument has, the more precise it can be.
Accuracy – when the experimental value is close to the actual value.
% Error = experimental – accepted value x 100
accepted value

21. What is the goal for a game of darts?
Hitting the Bulls Eye!

22. Label the following data as accurate, precise, neither, or both.
1) 200g, 1g, 40g
Neither
2) 78g, 80g, 79g
Precise
3) 16g, 14g, 17g
Accurate and Precise

23. How to use a graduated cylinder
Read the
meniscus

24. How to use a graduated cylinder
36.4 mL
19.0 mL
6.25 mL

25. Length - Rulers
3.7 3 4 5
3.6 3 4 5
3.63 3 4 5

26. Temperature
21.8
21.68

27. How to read a triple beam balanceg
Ohaus Triple Beam Balance Tutorial
Reading A Triple Beam Balance Tutorial

28. How to read a triple beam balanceg
Ohaus Triple Beam Balance Tutorial
Reading A Triple Beam Balance Tutorial

29. Significant Figures and Digits
A prescribed decimal that determines the amount of rounding off to be done base on the precision of the experiment.
ALWAYS ESTIMATE 1 DIGIT MORE THAN THE INSTRUMENT MEASURES.
Significant digits include measured digits and the estimated digit.
Exact Numbers – Do not involve estimation
ex. 12 in = 1 ft

30. VI. Significant Digits Use Atlantic-Pacific Rule – imagine a US map
decimal
point
decimal
point
Pacific
Atlantic
resent
bsent

31. 1100
2 significant digits
4 significant digits
1100.
8 significant digits
2 significant digits
0.025
5 significant digits
1,000,100
5 significant digits
Decimal Absent Start counting with the 1st nonzero digit and count all the rest.
Decimal Present Start counting with the 1st nonzero digit and count all the rest.

32. Significant Digits in Addition and Subtraction
Add or subtract numbers
Answer can only be as exact as the least exact number. (Look at the decimal place)
Ex cm cm
4.17 cm
4.2 cm

33. Significant Digits and Multiplication and Division
Multiply and Divide the numbers.
Round answer to the same number of significant digits as the number with the fewest significant digits.
Ex cm / cm
13.2

34. Atmospheric pressure is measured with a barometer
Atmospheric pressure is measured with a barometer. This is a glass tube sealed at one end and filled with Hg.

35. Types of Manometers

36. Open Manometers

37. Using a Manometer a device used to measure pressure
Reading a Manometer
Barometer containing Hg

38. Temperature Conversions Celsius and Kelvin
K = °C + 273
°C = K
Zero Point on Kelvin Scale – Absolute Zero
0 K and -273 °C
Kinetic energy is energy of motion. Temperature is a measure of kinetic energy. Since the temperature at absolute zero is a true zero, there is no particle motion Therefore, nothing can exist at absolute zero.

39. TEMPERATURE SCALES
                                                                                    

40. Measurements: basic to all sciences & all are comparisons to a standard
English – still used in US
Metric – devised in the late 1700’s in France
SI – Le Système Internationale d’Unités
Modern metric system (1960)
Based on 7 base units
Base units are modified by prefixes

41. SI Base Units meter (m) kilogram (kg) second (s) Kelvin (K) Length
Mass (SI standard unit)
Time
Temperature
Amount of a substance mole (mol)
Electric current ampere (A)
Luminous intensity candela (cd)
meter (m)
kilogram (kg)
second (s)
Kelvin (K)

42. The Meter
The original standard for the meter was kept in a safe in France.
The meter stick is a replica of that standard.
A meter is made up of 100 centimeters and 1000 millimeters.
Lasers are now used to determine the standard for a meter.

43. The Gram Mass is the amount of matter in an object.
1 cm3 of water = 1 gram.
The standard kilogram is kept under lock and key in Washington, DC and other cities around the world.

44. Metric Conversion

45. Derived Units Area: 2-D Volume: 3-D Density L x W (m2)
Solid - L x W x H (m3)
Liquid or irregular shaped object - graduated cylinder (L or cm3)
Density
mass/volume (kg/m3)

46. = The Liter The liter is 1000 mL 10cm x 10cm x 10cm
1 liter = 1000 cm3 = 1 dm3
1 milliliter = 1 cm3 = 1 cc = 20 drops

48. Prefix Meaning Scientific Notation
Abbreviation
Meaning
Scientific Notation
mega- M
1,000,000
1 x 106
kilo- k
1,000
1 x 103
hecto- h
100
1 x 102
deka- da 10
1 x 101
BASE UNIT
(g, m, L) 1
deci- d
0.1
1 x 10-1
centi- c
0.01
1 x 10-2
milli- m
0.001
1 x 10-3
micro- 
1 x 10-6
nano- n
1 x 10-9
pico- p
1 x 10-12

49. Length Relationships

50. Conversions between units
Factor-label method or dimensional analysis – based on using unit equalities
60 s = 1 min
60 s OR min
1 min s

51. Example 1: 3.6 x 104 s = ? days = 0.42 days = 4.2 x 10-1 days =
1 hr
60 min
1 day
24 hr
1 min
60 s =
0.42 days = 4.2 x 10-1 days
1 min
__________________
60 s
1 hr
__________________
60 min
1 day
__________________
24 hr
3.6 x 104 s x x x =

52. Example 2: 36 mm3 = ? cm3 = 0.036 cm3 36 mm3 1 cm3 mm3 1000 mm3 1 cm

53. Example 3: A room measures 12 feet by 15 feet
Example 3: A room measures 12 feet by 15 feet. Calculate the minimum number of square yards of carpet needed to cover this area.
180 ft2
1 yd2
= 20 yd2
9 ft2

54. A closer look at density
Physical = A characteristic of a substance that does not involve a chemical change
Examples: texture, state of matter, density, hardness, boiling point
Density = The ratio of the mass of a substance to the volume of the substance.
D = mass / volume

55. Density Column

56. Density

57. Which is more dense: Diet or Regular Soda?

58. Density of an Irregular solid:
1- Find the mass of the object
2- Find the volume if the
object by water displacement!

59. The characteristic plot for a Direct Relationship is a straight line graph.
Indirect Relationship
The characteristic plot for an Inverse Relationship is a curve of the type illustrated here. As one of the variables increases, the other decreases. Note: It is not a straight line sloping downward.

60. Use the following data to determine the density of aluminum.
Determine the density of aluminum from the analysis of data from 5 samples.
54.0-g sample has a volume of 20.0 mL
14.0-g sample has a volume of 5.0 mL
41.0-g sample has a volume of 15.0 mL
27.0-g sample has a volume of 10.0 mL
19.0-g sample has a volume of 7.0 mL
HINT: Graph the data with volume as the independent variable.
The slope of the line is the density.
Reminders: 1) Label both the x and y axis
2) Give your graph a descriptive title
3) Make a BEST FIT line/curve
4) Show work for slope on graph

61. Density Graph
BACK

62. Energy Transfer
Heat-energy that is transferred from one object to another due to a difference in temperature. (symbol for heat = q)
Temperature = a measure of the average kinetic energy of the particles in a substance. Temperature is an intensive property, and heat is an extensive property.
Thermochemistry – the study of heat changes in a chemical reaction.
Heat vs. Temperature

63. Calorimetry Calorimetry is the study of heat flow and measurement.
Calorimetry experiments determine the heats of reactions by making accurate measurements of temperature changes produced by a calorimeter.

64. Calorimeter

65. Calorimeter

66. Heat Capacity – amount of heat needed to raise the temperature of an object 1°C.
Specific Heat – amount of heat needed to raise 1g of a substance 1°C.
-Symbol for specific heat is C.

67. Heat and Temperature Formula for heat absorbed for released:
q = C x m x ∆T
Remember: Specific Heat of Water =
4.184 J/g· °C