1. Unit 1 Scientific Notation/Powers of 10 Significant Figures
Dimensional Analysis (Factor Label Method)

2. MATH IS THE
LANGUAGE OF
CHEMISTRY!!!

3. Scientific Notation
Scientist use special notation to express very large or very small numbers.
Example I: 300,000,000 m/sec can be written as…
3 x 108 m/sec
Ex II: 1,007,000,000 sec can be written as…
1.007 x 109 sec
Ex III: m can be written as…
4.76 x m

4. Converting Metric Measurements (PART 4 of Things to Know and Love)
To convert, move the decimal place the number of stairs you step on in the direction you are traveling OR use dimensional analysis.
kilo-
103
hecto-
102
deca-
basic unit
101 1
deci-
Example:
3.75 km = ? mm
10-1
centi-
10-2
milli-
? = 3,750,000 mm
10-3

5. SIGNIFICANT FIGURES
Scientists indicate the precision of measurements by the number of digits they report = sig. figs.
A value of 3.52 g is more precise than a value of g
All known digits plus one estimated digit
** the equipment used for a measurement will determine the number of sig. figs.

6. Significant Figures Atlantic - Pacific Rule:
Decimal Present: Count from the Pacific side
Decimal Absent: Count from the Atlantic side
Start counting at the first non-zero number and count until you reach the end of the number
Ex. I:
Decimal Present… Pacific (left)… 6 sig. figs.
Ex. II: 300,700
Decimal Absent… Atlantic (right)… 4 sig. figs. (the last 2 zeros are PLACE HOLDERS)

7. 5 (the first 3 zeros are PLACE HOLDERS) 0.0034050 L ___________
REVIEW
Determine how many significant figures are in each of the following measurements.
5 (the first 3 zeros are PLACE HOLDERS)
L ___________
m ___________
g ___________
47,900 mm ___________
7,000,000,001 miles ___________
8.07 Hz ___________ 5 5
3 (the last 2 zeros are PLACE HOLDERS) 10 3

8. More practice… 366.2 L ___________ 366 L 9,047,022 mg ___________
Round the following measurements off so that they each contain 3 significant figures.
366.2 L ___________
9,047,022 mg ___________
12.76 g ___________
999.9 J ___________
366 L
9,050,000 mg
12.8 g
1.00 x 103 J
Notice this one must be in scientific notation to have 3 sig. figs.

9. Significant Figures in Calculations
When multiplying and dividing, limit and round to the least number of significant figures in any of the factors.
Example:
23.0 x 432 x 19 = 188,784 = 190,000
The answer is expressed as 190,000 or 1.9 x 105 since 19 has only two sig. figs.

10. Significant Figures in Calculations
When adding and subtracting, limit and round your answer to the least number of decimal places in any of the numbers involved in the calculation.
Example:
= = 255.5
The answer is expressed as since 46.0 has only one decimal place.

11. REVIEW
Perform the prescribed operations. Round your answers to the proper # of sig. figs.
36.57 m / 3.21 s = ___________
41.376g g g=___________
5.67 m x m ___________
(5.83 m/ 2.67 s) /2.1 s ___________
9.374 V x 6 ___________
11.4 m/s
97.6 g
76.2 m2
1.0 m/s2
60 V
From now on, we will round all our answers to the correct # of significant figures.

12. EXTRA REVIEW Using a calculator for EXPONONETS Example 1:
(EE, EXP or x10x button)
Example 1:
(5.02 x 10-3) x ( x 105) =
*put in correct sig figs
= 3 sig figs
= 3180 or 3.18 x 103

13. Example 2 (use EE button!)
(2.99 x 106) x (2.334 x 10-3) = =
3 sig figs
6980

14. DIMENSIONAL ANALYSIS How old are you in seconds?
Go from number of years to number of seconds.
EX: 15 years old  _____ seconds old.
To do this, you need to use CONVERSION FACTORS (a ratio of equivalent values used to express the same quantity in different units)

15. Performing these conversions is a lot like going on a road trip.
Dimensional Analysis
Performing these conversions is a lot like going on a road trip.

16. ROAD TRIP!!!
Let’s say you want to travel from Oracle Jct to Casa Grande...
You must travel through Tucson… a two part trip.

17. Rule: You must stay on the roads & REMEMBER SIG FIGS!!!

18. DO NOT GO OFF ROAD!  X

19. Rule: You need a map. Sometimes the map can be in your head
Rule: You need a map. Sometimes the map can be in your head. But, not at first. (show all work!!)

20. GIVEN INFORMATION 1 kildurkin = 18 gallons 2 farkins = 1 kildurkin
1 hogshead = 63 gallons
1 barrel = 3.3 bushels
1 bushel = 8 gallons

21. Make a UNIT CONVERSION MAP
Draw connections between the units in the conversion factors…
(as you draw connections, check that conversion factor off the list)
It’s kind of like a road map…

22. hogshead
kildurkins
farkins
gallons
barrel
bushel

23. General Format...
given
going to = X
coming from

24. Let’s calculate
Convert 14 gallons to kildurkins

25. Convert 14 barrels to hogshead

26. Convert 3.00 bushels to farkins

27. Now you try one. How many farkins is 3.00 bushels?
End Here
hogshead
kildurkins
farkins
gallons
Start Here
barrel
bushel
This will require 3 Conversions.

28. = 2.67 farkins bushels gallons kildurkins farkins 8.0 gallonsX X X
1.0 bushel
18 gallons
1.0 kildurkin
= 2.67 farkins

29. Wow! How Cool Is That!

30. Handout: Fun Factor Label
Piece of lined paper (landscape format)
Front is web for Distance and back is for Vol.
Conversion Factors: change to x 10-10
Let’s do league  km  m  cm to start
You finish web, then do #3,6,7,9
Then do vol. web
Then finish questions #4, 5, 8, 10
FINISH FOR HW