II. Units of Measurement

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CH. 5 - MEASUREMENT

• II. Units of Measurement

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A. Number vs. Quantity

• Quantity - number unit

UNITS MATTER!!
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B. SI Units
Quantity
Base Unit
Abbrev.
Symbol
Length
meter
m
l
Mass
kilogram
kg
m
Time
second
s
t
Temp
kelvin
K
T
Amount
mole
mol
n
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B. SI Units
Prefix
Symbol
Factor
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C. Derived Units

• Combination of base units.
• Volume (m3 or cm3)
• length ? length ? length

1 cm3 1 mL 1 dm3 1 L

• Density (kg/m3 or g/cm3)
• mass per volume

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D. Density
Mass (g)
Volume (cm3)
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Problem-Solving Steps

• 1. Analyze
• 2. Plan
• 3. Compute
• 4. Evaluate

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D. Density

• An object has a volume of 825 cm3 and a density
  of 13.6 g/cm3. Find its mass.

GIVEN V 825 cm3 D 13.6 g/cm3 M ?
WORK M DV M (13.6 g/cm3)(825cm3) M 11,200
g
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D. Density

• A liquid has a density of 0.87 g/mL. What volume
  is occupied by 25 g of the liquid?

GIVEN D 0.87 g/mL V ? M 25 g
V 29 mL