Density

DensityDensity

Mass per unit volume of a Mass per unit volume of a substancesubstance

• Density: the amount of matter in a given space, or volume.

• Density = Mass/Volume

Physical Properties

Extensive physical properties depend on the amount (extent) of matter present Examples: length, volume and mass

Intensive physical properties are intrinsic (fundamental) and do not depend on the amount of material presentExamples: color, malleability, ductility, boiling pointCan be used to identify a substance

Is density an extensive or intensive property?

DensityDensity

• May change at higher temperaturesMay change at higher temperatures

• Unit of density is grams/cubic Unit of density is grams/cubic centimeter or g/cmcentimeter or g/cm33

• Unique so can be used to identify Unique so can be used to identify mattermatter

ReviewReview

• Mass: the amount of matter in an Mass: the amount of matter in an objectobject

• Volume: the amount of space an Volume: the amount of space an object takes upobject takes up

• Density = Density = MassMass

VolumeVolume

Remember: “Density will break your Remember: “Density will break your heart”heart”

Density of a rectangular Density of a rectangular solidsolid

1.1. Using the metric ruler, measure Using the metric ruler, measure length, width and height of the length, width and height of the objectobject

2.2. Find the mass of the solid.Find the mass of the solid.

3.3. Use the formula: Volume = length Use the formula: Volume = length x width x heightx width x height

4.4. Density = mass/volumeDensity = mass/volume

Displacement:Displacement:density of an irregular objectdensity of an irregular object

1.1. Find the mass of the object.Find the mass of the object.

2.2. Place some water in the graduated Place some water in the graduated cylinder and record the volume.cylinder and record the volume.

3.3. Carefully add the object.Carefully add the object.

4.4. Read the new volume.Read the new volume.

5.5. Subtract the old volume from the new Subtract the old volume from the new volume.volume.


Density of LiquidsDensity of Liquids

1.1. Immiscible: liquids that are insoluble in Immiscible: liquids that are insoluble in one anotherone another

2.2. Density of water = 1 g/cmDensity of water = 1 g/cm33

3.3. To determine:To determine:1.1. Find the mass of the empty graduated cylinderFind the mass of the empty graduated cylinder

2.2. Find the mass of the graduate + liquidFind the mass of the graduate + liquid

3.3. 2 - 1 = mass of liquid2 - 1 = mass of liquid

4.4. Read the volume of the liquidRead the volume of the liquid


Section 2 Physical PropertiesChapter 2

Physical Properties, continued• Using Density to Identify Substances Look at

the table below to compare densities of several common substances.


Physical Properties, continued• Liquid Layers The graduated cylinder below

contains six liquids. Each liquid is a different density so the liquids form layers.

• Density of Solids Knowing thedensity of a substance can alsotell you what kind ofsubstance it is.

1. What could you use to tell pyrite (fool’s gold) and gold apart?

A volume

B density

C mass

D state

Chapter 2 Standardized Test Preparation

2. What do you think would happen if you placed a nugget of pyrite into a beaker of mercury?

F The pyrite would sink.

G The pyrite would dissolve.

H The mercury and the pyrite would react.

I The pyrite would float.


3. If a nugget of pyrite and a nugget of gold each have a mass of 50 g, what can you conclude about the volume of each nugget?

A The volume of pyrite isgreater than the volume of gold.

B The volume of pyrite isless than the volume of gold.

C The volumes of thesubstances are equal.

D There is not enoughinformation to determine the answer.


4. Which substance has the lowest density?

F helium

G pyrite

H mercury

I gold


1. Imagine that you have discovered a new element, and you want to find its density. It has a mass of 78.8 g and a volume of 8 cm3. To find the density of the element, you must divide the element’s mass by its volume. What is the density of the element?

A 0.102 g/cm3

B 0.98 g/cm3

C 9.85 g/cm3

D 630.4 g/cm3


2. Many soft drinks come in bottles that contain about 590 mL. If the density of a soft drink is 1.05 g/mL, what is the mass of the drink?

F 0.0018 g

G 498.2 g

H 561.9 g

I 619.5 g


3. If you have 150 g of pure gold and the density of gold is 19.32 g/cm3 , what is the volume of your gold nugget?

A 2.898 cm3

B 7.76 cm3

C 0.98 cm3

D 0.13 cm3


4. Three objects have a mass of 16 g each. But their volumes differ. Object A, a liquid, has a volume of 1.2 mL. Object B, a solid, has a volume of 3.2 cm3. Object C, another solid, has a volume of 1.9 cm3. Which object is the least dense?

F object A

G object B

H object C

I There is not enough information to determine the answer.


Density

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