DensityDensity

• Density is a _________ property of Density is a _________ property of matter.matter.

• Density can be defined as the Density can be defined as the amount of ________ in a given amount of ________ in a given ________.________.

physicalphysical

mattermatter spacespace

• Example:Example:

Two objects have the exact same Two objects have the exact same volume,volume,

but one is made of more matter.but one is made of more matter.

• Example:Example:

Which has more mass, a kilogram of Which has more mass, a kilogram of feathers, or a kilogram of lead?feathers, or a kilogram of lead?

• Density is a physical property of a substance that is used to identify that substance.

• The size of the object does not change the density. The density of lead is always going to be the same.

DensitDensity of y of LeadLead

DensitDensity of y of LeadLead

Density Density of Leadof Lead

• Relative density:Relative density:

Matter that is less dense will float on Matter that is less dense will float on matter that is more dense.matter that is more dense.

• Calculating density:Calculating density:

If you know the ________ and ________ If you know the ________ and ________ of an object, you can find its of an object, you can find its density.density.

massmassvolumevolume

The formula:The formula:

density = mass/volume density = mass/volume

OR OR

D = mD = m ------------

vv

We LOVE

We LOVE

density!!!

density!!!

• Identifying your units!

The base unit for mass (m) of an object is grams (g).

The base unit for volume of a solid is cubic centimeters (cm3).

The base unit for volume of a liquid is milliliters (ml)

• How to find volume:

Regular solid: a solid which the sides can be measured using a ruler

to get the volume.

V= L x W x H

Irregular solid: a solid with sides that are not capable of being measured with a ruler.

Example: odd shaped rockFor this type of object we use

WATER DISPLACEMENT

Water DisplacementTo Find the volume of an

irregular solid:1. Using a graduated cylinder fill with water to a specific amount such as 100 ml.

2. Slowly lower object in to the graduated cylinder (the water will rise).

3. Subtract the final amount from the initial amount and that will be the volume of the object.

4. Convert from ml to cm3.

Rule of Rule of Thumb:Thumb:

Practice Problem 1

•A 800g rock has a volume of 8cm3. What is the density

of the rock?

Practice Problem 2

• A  piece of wood that measures 3.0 cm by  6.0 cm by 4.0 cm has a mass of 80.0 grams. What is the density of the wood? Would the piece of wood float in water?  (volume = L x W x H)

Practice Problem 3

• Archimedes was commissioned to determine if the crown given to the king was pure gold or not. If the crown had a mass of 882 grams and displaced 50 mL of water, was the crown pure gold?

• The density of Pure Gold is 19.3 g/cm3.