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Density & TemperatureUnit 1: Measurement & matter
Aim: What determines the density of a substance?
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Density
Ratio of the mass of an object to its volume
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Density• Commonly used to identify
substances
• Explains why things float
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How Does an Ice Cube Float?
A B C
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Density of water is 1 g/mL
Relative: In relation to
More Dense > 1 g/mLLess Dense < 1 g/mL
Density of Water
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Which will float? Object with higher density
than water?
Or
Object with lower density than water?
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Density & Volume Increase in volume, decreases the
density
What type of relationship is this? Indirect Inversely proportional
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Why Did the Titanic Sink??
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Density & Mass As mass increases, density increases
What type of relationship is this? Directly proportional
1. the “Compactness” of an object
2. Mass of particles there are per unit of area
3. How an object uses its space
Density [in words]
Density [Visual]:
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Calculating density
V
m
d
Example #1An unknown substance has a mass of 8.7g and a volume of 3.2cm3. What is the density of the substance in sig figs?
A: 2.7 g/cm3
Example #2
What is the volume of a pure silver coin that has a mass of 14g in sig figs? The density of silver (Ag) is 10.5g/ml
A: 1.3 `ml
Volume: the amount of space an object takes up
What are two ways we measure volume?
•Video
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Measuring Volume
Volume [=] mL [=] cm 3
With a ruler:V= L x W x H [=] cm x cm x cm
With glassware (water displacement):1mL [=] 1cm 3
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Displacement
Usually used for awkward shaped objects
Final Volume
Initial Volume
VolumeOf
Object=
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TemperatureMeasure of how hot/cold an
object is
Scientists Use 2 Temperature Scales
CelsiusDevised by Swedish Astronomer Anders Celsius. Temperature scale most commonly used for scientific work; freezing point of water =0˚C ; boiling point =100˚C
KelvinProposed by Lord William Kelvin0 K= lowest possible temperature or absolute zero
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Converting Between the 2
Celsius to KelvinK =˚C + 273
Kelvin to Celsius
˚C= K─273
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