1. Chapter 3 Scientific Measurement 3.2 Units of Measurement
3.1 Using and Expressing
Measurements
3.2 Units of Measurement
3.3 Solving Conversion Problems
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2. Abbreviated from the French name, Le Système International d’Unités
Using SI Units
SI Units
Abbreviated from the French name, Le Système International d’Unités
Based on metric system.
Adopted in 1960.
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3. Using SI Units
From these base units, all other SI units of measurement can be derived (i.e., volume, density, and pressure)
SI Base Units
Quantity
SI base unit
Symbol
Length
meter m
Mass
kilogram kg
Temperature
kelvin K
Time
second s
Amount of substance
mole
mol
Luminous intensity
candela cd
Electric current
ampere A
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4. Prefixes are used for very large and very small lengths.
Using SI Units
Units of Length
SI unit: meter (m).
Prefixes are used for very large and very small lengths.
All metric units are based on multiples of 10. As a result, you can convert between units easily.
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5. Commonly Used Metric Prefixes
Using SI Units
Commonly Used Metric Prefixes
Prefix
Symbol
Multiplier
Factor
kilo k
1000
103
hecto h
100
102
deca da 10
101
------
-----
Base Unit
(meter, gram, liter, etc)
deci d
0.1
10-1
centi c
0.01
10-2
milli m
0.001
10-3
King Henry Died By Drinking Chocolate Milk
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6. Volume - space occupied by matter
Using SI Units
Units of Volume
Volume - space occupied by matter
For a rectangular solid, V = L x W x H
SI unit: cubic meter (m3)
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7. A more convenient unit is the liter.
Using SI Units
Units of Volume
A more convenient unit is the liter.
Liter (L): volume of a cube that is 10 centimeters (10 cm) along each edge
10cm x 10cm x 10cm = 1000cm3 = 1L
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8. A smaller, non-SI unit of volume is the milliliter (mL).
Using SI Units
Units of Volume
A smaller, non-SI unit of volume is the milliliter (mL).
1mL = 1 cm3
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9. Units of Mass Using SI Units
Mass – a measure of the quantity of matter
SI unit: kilogram (kg)
1 kg = mass of 1 L of liquid water at 4 deg C.
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10. Weight - force that measures the pull on a given mass by gravity.
Using SI Units
Units of Mass
Weight - force that measures the pull on a given mass by gravity.
Weight of an object can change with location.
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11. Density: ratio of the mass of an object to its volume.
SI unit: kilograms per cubic meter (kg/m3)
mass
volume
Density =
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12. Density
This figure compares the density of four substances: lithium, water, aluminum, and lead.
Increasing density (mass per unit volume)
10 g
0.53 g/cm3
19 cm3
10 cm3
3.7 cm3
0.88 cm3
1.0 g/cm3
2.7 g/cm3
0.88 g/cm3
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13. Because of differences in density, liquids separate into layers.
As shown at right, corn oil floats on top of water because it is less dense.
Corn syrup sinks below water because it is more dense.
Corn oil
Water
Corn syrup
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14. Densities of Some Common Materials
Interpret Data
Densities of Some Common Materials
Solids and Liquids
Gases
Material
Density at 20°C (g/cm3)
Density at 20°C (g/L)
Gold
19.3
Chlorine
2.95
Mercury
13.6
Carbon dioxide
1.83
Lead
11.3
Argon
1.66
Aluminum
2.70
Oxygen
1.33
Table sugar
1.59
Air
1.20
Corn syrup
1.35–1.38
Nitrogen
1.17
Water (4°C)
1.000
Neon
0.84
Corn oil
0.922
Ammonia
0.718
Ice (0°C)
0.917
Methane
0.665
Ethanol
0.789
Helium
0.166
Gasoline
0.66–0.69
Hydrogen
0.084
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15. Calculate how many seconds are in one year (assuming 365 days
Temperature Scales
Do Now:
Calculate how many seconds are
in one year (assuming 365 days
in one year).
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16. Temperature: measure of how hot or cold an object is.
Temperature Scales
Temperature: measure of how hot or cold an object is.
SI unit: Kelvin (K)
Common unit: Celsius
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17. Note: with the Kelvin scale, the degree sign is not used
Temperature Scales
Note: with the Kelvin scale, the degree sign is not used
Celsius
Kelvin
100
divisions
100°C
Boiling point
of water K
0°C
Freezing point K
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18. Temperature Scales
One degree Celsius is equivalent to one Kelvin on the Kelvin scale.
To convert between the temperature scales,
K = °C + 273
°C = K – 273
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19. Converting Between Temperature Scales
Sample Problem 3.7
Converting Between Temperature Scales
Normal human body temperature is 37°C. What is this temperature in kelvins?
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20. Converting Between Temperature Scales
Sample Problem 3.7
Converting Between Temperature Scales
Normal human body temperature is 37°C. What is this temperature in kelvins?
K = °C = = 310 K
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21. END OF 3.2
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