DENSITY

Mr. Bantay - Oceanography

LAB OVERVIEW: Density

• The Earth is structured on the basis of DENSITY

What is Density?

• Density is described as the amount of matter within a given amount of volume.

• Simply, it’s the amount of molecules in a given amount of space.

• As a result, substances with a higher density will

settle to the bottom and substances with lower density will rise.

• The size of the substance will NOT affect DENSITY.

Density• Examples:

a) Cold water/air b) Warm water/air

Let’s Practice

• Pick up worksheet and calculator.

• Answer questions.

How do we find the density of a substance?

1. You need to know the MASS.

-simply use a scale or triple beam balance to obtain its mass (in grams).

2. You need to know its VOLUME.

The OBJECTS

The OBJECTS

FORMULA?

L x W x H

Length = 6cm

FORMULA?

L x W x H

Length = 6cm

Height = 4cm

FORMULA?

L x W x H

Length = 6cm

Height = 4cm

Width = 2cm

FORMULA?

L x W x H

Length = 6cm

Height = 4cm

Width = 2cm

So, the VOLUME of this object is

48 cm3

The OBJECTS

Find VOLUME

The METHOD

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

1. Note the water level

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

2. Place the object in liquid

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

3. Note difference in water level

The water level changed 15mL

We can say the rock displaced 15mL

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

It gets better!

-40mL

-35mL

-30mL

-25mL

-20mL

-15mL

-10mL

-5mL

Volume of our rock…

•Can’t use the volume formula (no edges)…•Can’t use the displacement technique….

Steps…First find the MASS:Find the mass of the container = “a”Fill container with water and obtain the mass of

both = “b”Find mass of JUST WATER = “b” – “a”

Now let’s find the VOLUME:Simply find the volume of the container.

Use density formula: D = mass/volume

Density• Today, you will be finding the DENSITY OF several

substances:

1. Water

2. A block of wood

3. A rock called granite (a rock that makes up the Earth’s continental crust)

4. A rock called basalt (a rock that makes up the Earth’s oceanic crust)

5. 5 minerals: pyrite, galena, quartz, fluorite, topaz

THE EQUATION

D =M

V

THE TRICK

Cover up the one you want to solve for!

Let’s solve for VOLUME.

“M over D”

is remaining

so we divide!

Let’s solve for Density.

“M over V”

is remaining

so we divide!

Let’s solve for Mass.

“D next to V”

is remaining

so we

multiply!

Density solutions…Water = 1 g/mL3

Wooden Block = .50 g/cm3

Granite = 2.7 g/cm3

Basalt = 3.0 g/cm3