1. DATA ANALYSIS
Measurement; Units; Calculations; Significant Figures; Prefixes; Dimensional Analysis
Neely's Chemistry

2. MEASUREMENT Used to measure properties
SI System based on the Metric System
“Systeme International”
Base Units & Derived Units
Adopted by scientists in 1960
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3. BASE UNITS Property Do not depend on other units to describe them
Name
Unit Symbol
Property
meter m
length
kilogram kg
mass
second s
time
ampere A
electric current
kelvin K
temperature
candela cd
luminous intensity
mole
mol
amount of substance
Neely's Chemistry

4. TEMPERATURE Measures average kinetic energy in a substance
Heat flows from higher to lower temp.
Kelvin Temperature T = oC + 273
Ex. 25oC is taken as “room temperature” ………………... What is this in kelvin?
T = = 298 K (not 298oK)
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5. An experiment is performed at 378 K. What is this temperature in oC?
Ans. 105oC
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6. DERIVED UNITS Defined by combination of base units EXAMPLE:
Length is used to define Area & Volume
Area = length2
Volume = length3
The area of a 10 cm by 8 cm rectangle is
10 cm x 8 cm = 80 cm2
The volume of a 2 cm x 4 cm x 6 cm rectangular solid is 48 cm3
Note: When working math problems always do the same thing with the units that you do with the numbers. It will always give you correct units, etc.
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7. 10 cm x 10 cm x 10 cm is a volume of 1 liter
Liter and cm3 or mL are convenient laboratory volume units
1 cm3 = 1 mL
1 Liter
10 cm x 10 cm x 10 cm
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8. DENSITY an important derived unit
Defining Equation
mass
D =
volume
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9. “I Luv Density”
D =
Can u see “m over v”
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10. A block of wood with a density of 0. 95 g/cm3 is cut exactly in half
A block of wood with a density of 0.95 g/cm3 is cut exactly in half. What is the resulting density of each half ?
Density will be 0.95 g/cc for each piece.
Density is an intensive property.
It does not depend on the size of the sample.
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11. Liquid Hg has a density of 13. 5 g/mL. What is the mass of 20
Liquid Hg has a density of 13.5 g/mL. What is the mass of 20.0 mL of Hg?
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12. SIGNIFICANT FIGURES and MEASUREMENTS
quantities or numbers go with units to have a meaningful measurement.
Each measured digit is a “Significant Figure”
Ex cm has __ sig figs cm has ___ sig figs.
How many sig figs in 9.07 cm?
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13. How Many Sig Figs in: 10.8 m ___ 3 sig figs 120. m ___ 130 g ___
2 sig figs (the last zero implies but does not give a decimal)
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14. How many sig figs? 0.59 L 2 sig figs (0 merely there to “hold place”)
2 sig figs (all the zero’s “hold place”)
0.0340
3 sig figs (only the 1st 2 zero’s “hold place”. The last zero is a measured zero.)
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15. Counting Significant Figures when a decimal is present
Count from left to right 
Start counting sig fig digits when you get to the first non-zero
Any zeros that occur after the first non-zero digit must count as significant
Ex. Sig figs in? a) ___
b) ___
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16. Counting Significant Figures when a decimal is not present
Count from right to left 
Start counting sig fig digits when you get to the first non-zero
Any zeros that occur after the first non-zero digit do not count unless they are “sandwich zero’s”
Ex. Sig figs in? a) ___
b) 240,000 ___
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17. Complete the Significant Figure WorkSheet
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