1. Unit 1: Measurement and Conversions
“CHEMISTRY IS THE SCIENCE OF CHANGE. It looks at all the different kinds of substances and how they interact with each other. It is going on all around us all the time, as well as in the scientific laboratory and in the chemical industry. People in widely differing walks of life use chemistry everyday – the doctor and the chef, the farmer and the builder. Chemistry comes to the aid of the manufacturer of food, and also to the brewer and wine maker. The technician in the hospital laboratory uses chemistry to check for infections in blood samples. The forensic scientists uses chemistry to solve crimes. In agriculture, chemistry is used to increase the yields of crops and to control many pests. Chemicals keep the water supply safe and swimming pools clean. One of the largest industries in the world is the petrochemical industry – this industry is mainly associated with gasoline and the chemicals that come from crude oil. Drugs, synthetic dyes, plastics, and fabrics are produced by chemical means from nature’s raw materials.”
Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 6

2. Scientific Notation Review
Often used to express very large or very small numbers. Also used to maintain correct number of significant figures.
Form: (# from 1 to 9.999) x 10exponent
800
2531
0.0014
= 8 x 10 x 10
= 8 x 102
= x 10 x 10 x 10
= x 103
= 1.4 / 10 / 10 / 10
= 1.4 x 10-3

3. Scientific Notation Practice
Change the given number to standard form.
1.87 x 10–5 =
3.7 x 108 =
7.88 x 101 =
2.164 x 10–2 =
370,000,000
78.8
(-) exponent = number < 1
(+) exponent = number > 1

4. Scientific Notation Practice
Change the given number into scientific notation.
12,340 =
0.369 =
0.008 =
1,000,000,000 =
1.234 x 104
3.69 x 10–1
8 x 10–3
1 x 109

5. Significant Figures
about…
A student is combining separate water samples, all of differing volumes, into one large bucket. Samples A, B and C are 25.5 mL, mL and 51 mL, respectively. Once combined, what is the total volume of all the samples?
92.87 mL
NO!
Because the samples were each measured with a different level of precision, we must factor that into our calculations by identifying what are called significant figures.

6. Measurement and Accuracy
The last digit of any measured number is assumed to be an estimate (uncertain)
The second to last digit is assumed to be known with certainty (based on a line)
A (25.5 mL) B (16.37 mL) C (51 mL) 60 26 50 25
16.4
16.3

7. Identifying Significant Figures
Counting SF’s in a number
Non-zero numbers: ALWAYS count as SF
Zeroes
Left: NEVER count as SF ( )
Middle: ALWAYS count as SF (5001)
Right: sometimes…
w/ decimal point: count as SF (25.10)
w/o decimal point: DO NOT count as SF (8200)
Exact Numbers: IGNORE SF
Counts (28 students in this class)
Constants (1 mol = x 1023)
Conversions (1 in = 2.54 cm)
Relative to the non-zero numbers.

8. How many Sig Figs? Measurement Number of SF Measurement Number of SF
0.030 kg
x 106 mg
6 x 104 sec g
20.06 cm
1.050 m 2 7 1 5 4
0.12 kg cm kg
6.00 x 106 kg
409 cm dm g 2 7 1 3 5 4

9. Sig Figs with Calculations
Note: For any calculations, always perform the entire calculation without rounding, and then round the final answer.
Addition/Subtraction
Round the answer to the LEAST number of decimal places found (least precise) =
Multiplication/Division
Round the answer to the smallest number of SF found
5.282 x 3.42 =
→ rounded to 48.7
→ rounded to 18.1
(3.42 only has 3 SF)

10. Back to the original question…
A student is combining separate water samples, all of differing volumes, into one large bucket. Samples A, B and C are 25.5 mL, mL and 51 mL, respectively. Once combined, what is the total volume of all the samples?
25.5 mL mL + 51 mL = mL
93 mL
Could I write that as 93.0?
NO!

11. More practice with SF
If you made measurements of three samples of water (128.7 mL, 18 mL and mL), and then poured all of the water together in one, unmarked container, what total volume of water should you report? Support your answer.
128.7 mL + 18 mL mL = mL
170. mL or 1.70 x 102 mL

12. Practice with Sig Fig Calculations
= x 10-9
report -6 x 10-9 (1 SF)
= x 109
report 3.6 x 109 (2 SF) =
report 15.6 (tenths place)
= 16.27
report 20 (tens place)
= x 10-5
report 1.7 x (2 SF)
Complete calculation, and then follow order of operations to determine how many SF would be carried for each step

13. The Metric System
from Industry Week, 1981 November 30

14. SI System The International System of Units
abbreviated SI from the French Le Système international d'unités
Based on the metric system (with small variations)
Based on powers of ten
Uses prefixes to differentiate between powers
Used in nearly country except U.S. (Liberia and Myanmar are some others…)

15. The International System of Units
Quantity Name Symbol
Volume liter L
Length meter m
Mass kilogram kg
Time second s
Amount of substance mole mol
Thermodynamic temperature Kelvin K
Electric current amperes amps
Luminous intensity candela cd
Internet Access to the National Institute of Standards and Technology
“To be or not to be”: the English or the Metric system
The English system of measurement used today in the United States originated in the decrees of English monarchs. The French Revolution produced the overthrow of the French monarchy and in 1799 it also led to the creation of the set of weights and measures we call the metric system. The metric system was legalized for use in the United States in 1866 along with the traditional English system. Today the only countries in the world that do not use the metric system are the United States of America, Liberia and Myanamar.
United States government policy toward the Metric System
This part is to access the following URLs for the National Institute of Standards and Technology, NIST, and review the evolution of the relationship between the United States and the Metric System. You can answer the first question after reviewing this NIST page.
What was the year when the United States signed the “Treaty of the Meter”?
Access this FDA page to answer the following question.
What does the term “Both timeless and toothless” have to do with the Metric Conversions Act of 1975? In your opinion does this influence the pace of metrification in the United States?
Name ____________________ Hr ____
Another part of your assignment is to write a brief argument on the back of this page for adopting the metric system and replacing the English system. Lastly you are to write an argument for continuing the current pattern of using two systems.
Argument for adopting the Metric system and dropping the English system.
Argument for retaining both the English system and the Metric system
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 16

16. Area and Volume: Derived Units
Area = length x width
= m x 3.0 m
= 15 ( m x m)
= 15 m2
Volume = length x width x height
= m x 3.0 m x 4.0 m
= 60. ( m x m x m)
= 60. m3

17. Derived Units Commonly Used in Chemistry
Quantity Name Symbol
Area square meter m2
Volume cubic meter m3
Force newton N
Pressure pascal Pa
Energy joule J
Power watt W
Voltage volt V
Frequency hertz Hz
Electric charge coulomb C

18. Prefixes in the SI System
The Commonly Used Prefixes in the SI System
Power of 10 for
Prefix Symbol Meaning Scientific Notation
_______________________________________________________________________
mega- M ,000,
kilo- k ,
deci- d
centi- c
milli- m
micro- m
nano- n
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 118

19. Quantities of Mass Giga- Mega- Kilo- base milli- micro- nano- pico-
Earth’s atmosphere
to 2500 km
1018 g
Quantities of Mass
1015 g
1012 g
Ocean liner
Giga-
Mega-
Kilo-
base
milli-
micro-
nano-
pico-
femto-
atomo-
109 g
Indian elephant
106 g
Average human
103 g
1.0 liter of water
100 g
10-3 g
10-6 g
Grain of table salt
10-9 g
10-12 g
10-15 g
10-18 g
Typical protein
10-21 g
Uranium atom
10-24 g
Water molecule
Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 25

20. Reporting Measurements
Must use significant figures
Report what is known with certainty
Using dashes
Add ONE digit of uncertainty beyond that
Using estimation
By adding additional numbers to a measurement – you do not make it more precise. The instrument determines how precise it can make a measurement. Remember, you can only add ONE digit of uncertainty to a measurement.
The implication is that for any measurement, the last digit is an estimate and uncertain, and the next to last is known with certainty
Davis, Metcalfe, Williams, Castka, Modern Chemistry, 1999, page 46

21. Practice Measuring cm 1 2 3 4 5 4.5 cm cm 1 2 3 4 5 4.54 cm cm 1 2 3 41 2 3 4 5
4.5 cm cm 1 2 3 4 5
4.54 cm
PRACTICE MEASURING
Estimate one digit of uncertainty.
a) 4.5 cm
b) * 4.55 cm
c) 3.0 cm
*4.550 cm is INCORRECT while 4.52 cm or 4.58 cm are CORRECT (although the estimate is poor)
By adding additional numbers to a measurement – you do not make it more precise. The instrument determines how precise it can make a measurement. Remember, you can only add ONE digit of uncertainty to a measurement.
In applying the rules for significant figures, many students lose sight of the fact that the concept of significant figures comes from estimations in measurement. The last digit in a measurement is an estimation.
How could the measurement be affected by the use of several different rulers to measure the red wire?
(Different rulers could yield different readings depending on their precision.)
Why is it important to use the same measuring instrument throughout an experiment?
(Using the same instrument reduces the discrepancies due to manufacturing defects.) cm 1 2 3 4 5
3.0 cm
Timberlake, Chemistry 7th Edition, page 7

22. Measurement/Sig Fig Practice
Draw a picture showing the markings (graduations) on glassware that would allow you to make each of the following volume measurements of water and explain your answers (the numbers given are as precise as possible):
a mL b. 18 mL c mL
Mark every 1 mL
Mark every 10 mL
Mark every 0.1 mL

23. Implied Range of Uncertainty50 60 40 30
Implied range of uncertainty in a measurement reported as 50. cm (±5) 5 6 4 3
Implied range of uncertainty in a measurement reported as 5.0 cm (±0.5)
When the plus-or-minus notation is not used to describe the uncertainty in a measurement, a scientist assumes that the measurement has an implied range, as illustrated above. The part of each scale between the arrows shows the range for each reported measurement. 5 6 4 3
Implied range of uncertainty in a measurement reported as 5.00 cm (±0.05)
Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 32

24. Reading a Meniscus line of sight too high reading too high10 8 6
10 mL
line of sight too high
reading too high
proper line of sight
reading correct
line of sight too low
reading too low
graduated
cylinder

25. 20 ?
1.50 x 101 mL
15 mL ?
15.0 mL
A student reads a graduated cylinder that is marked at mL, as shown in the illustration.
Is this correct? NO
Express the correct reading using scientific notation mL or 1.50 x101 mL 10

26. Conversion Factors How many cm are in 1.32 meters? equality:
1 m = 100 cm
(or 0.01 m = 1 cm)
applicable conversion factors:
______
1 m
100 cm
______
1 m
100 cm or
1.32 m
1 m
100 cm
132 cm =
We use the idea of unit cancellation
to decide upon which one of the two
conversion factors we choose.

27. ( ) ( ) Both ways are equally good! OR… ____ ______
1. How many kilometers is 15,000 decimeters?
15,000 dm
10 dm
1 m
1,000 m
1 km
1.5 km =
OR… ( )
____ ( )
______
10 dm
1 m
1,000 m
1 km
15,000 dm

28. ( ) ( ) ( ) ____ _____ ____ 2. How many seconds is 4.38 days? 24 h 1 d
60 min
1 min
60 s
4.38 d
378,432 s =
If we are accounting for significant figures, we would change this to…
3.78 x 105 s

29. ( ) ( ) ( ) ( ) 3. Convert 41.2 cm2 to m2 ______ ______ ______=
0.412 m2
WRONG! =
0.412 cm.m
Recall that… 41.2 cm2 = 41.2 cm.cm ( )
______ ( )
______
41.2 cm.cm
100 cm
1 m
100 cm
1 m = m2 ( )
________
(100)2 cm2
1 m2
41.2 cm2 = m2

30. ( ) 4. Convert 41.2 cm2 to mm2 _____ Recall that… 1 cm = 10 mm ( )2
( )2
( )2 ( )
_____
1 cm2
102 mm2
41.2 cm2 =
4,120 mm2

31. ( ) ( ) ( ) ( ) ( ) 5. Convert to 480 cm3 to m3 _____ _____ _____
cm.cm.cm ( )
_____ ( )
_____ ( )
_____
100 cm
1 m
480 cm 3 2
100 cm
1 m
100 cm
1 m = or ( )
_____
100 cm
1 m 3
480 cm3 = m3 or
1 m cm ( )
_________ 3
480 cm3
4.8 x 10-4 m3 =

32. Comparison of English and SI Units
1 inch
2.54 cm
1 inch = 2.54 cm
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 119

33. SI-US Conversion Factors
Equality Conversion Factors
Length
2.54 cm
1 in
1 in
2.54 cm
2.54 cm = 1 in.
and
39.4 in
1 m
1 m
39.4 in.
1 m = 39.4 in.
and
Volume
946 mL
1 qt
1 qt
946 mL
946 mL = 1 qt
and
1.06 qt
1 L
1 L
1.06 qt
and
Dominoes Activity
1 L = 1.06 qt
Mass
453.6 g
1 lb
1 lb
453.6 g
453.6 g = 1 lb
and
2.20 lb
1 kg
1 kg
2.20 lb
1 kg = 2.20 lb
and

34. Practical Conversions
Teachers get a lot of grief from normal workers because they only work 36 weeks a year. How many extra hours, per day, would a teacher have to put in to match the typical worker, assuming a teacher works 8 hrs per day for those 36 weeks?
What assumptions must we make?

35. Density Review  how tightly packed the particles are m V D Density =
Typical units:
g/cm3 for solids
g/mL for fluids
Glass: liquid or solid?
liquids
and gases

36. Monty Python’s take on analytical science and density with regard to witches…

37. Density Review 1. A sample of lead (Pb) has mass
22.7 g and volume 2.0 cm3. Find
sample’s density. m V D
= 11
2. Another sample of lead occupies 16.2 cm3
of space. Find sample’s mass. V
m = D V
= 180 g

38. More Density Review Problems…
3. A g solid cylinder has radius 1.8 cm and height 1.5 cm. Find sample’s density.
4. A 153 g rectangular solid has edge lengths 8.2 cm, 5.1 cm, and 4.7 cm. Will this object sink in water?

39. 3. A 119.5 g solid cylinder has radius 1.8 cm and height 1.5 cm. Find
sample’s density.
1.5 cm
1.8 cm m V D
2 SF
V = p r2 h
= p (1.8 cm)2(1.5 cm) =
cm3
= 7.8

40. this object sink in water?
8.2 cm
5.1 cm
4.7 cm
4. A 153 g rectangular solid
has edge lengths 8.2 cm,
5.1 cm, and 4.7 cm. Will
this object sink in water?
(Find object’s density and compare it to water’s density.)
2 SF m V D
V = l w h
= 8.2 cm (5.1 cm)(4.7 cm) =
cm3
= 0.78
< 1
No; it floats.

41. Will bowling balls sink or float in H2O?
If DBB > 1, it will sink
If DBB < 1, it will float
21.6 cm in diameter
Vsphere = 4/3 p r3
V = 4/3 p (10.8 cm)3 m V D
V = 5,276.7 cm3
m = D V
m = (1.0 g/cm3)( cm3)
m = g
Since the mass of a BB varies, let’s figure out at what mass it will sink v. float
…or 11.6 lbs

42. Measurements Metric (SI) units Prefixes Uncertainty Conversion factors
Length
Mass
Volume
Conversion
factors
Significant
figures
Density
Problem solving with
conversion factors
Timberlake, Chemistry 7th Edition, page 40