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