DENSITY

States of MatterStates of Matter

Properties describe matter. A block of wood, milk, and air all have properties. All the material on earth is in three states - solid, liquid, and gas. The "state" of the matter refers to the group of matter with the same properties. In other words, you group the objects together according to their properties.

States of matter group objects (matter) according to their similar properties (solid, liquid or gas).

The 3 States of Matter areThe 3 States of Matter are::

- Solid

- Liquid

- Gas

Solid Liquid Gas

Mass

• Mass is how much matter there is in an object

• Mass is not the same as weight

DensityDensity

What do you think density is?

Density is the mass of a substance per unit volume. ** Remember – Mass is how much matter there is in an object**

Volume is the amount of space an object occupies.

Take a look at the two boxes. Each box has the same volume because they both occupy the same amount of space…

Question: If each ball has the same mass, which box would weigh more? Why?

Answer:

The box with more balls has more mass per unit of volume. Therefore, the box with more balls is a denser material.

Comparing the Density of Objects to Water:

In chemistry, the density of many substances is compared to the density of water. Does an object float on water or does it sink? If an object such as a piece of wood floats on water, it is less dense than water vs. if a rock sinks, it is more dense than water.

Question: How has the density of different substances helped us to clean up oil spills in our oceans?

Hint – what happens when we mix oil and water

Oil Spill Clean up:

What happens when an oil tanker leaks into the ocean? Well, since oil is less dense than water, it tends to float atop the water. This provides some opportunity to clean up the oil spills by skimming the oil from the surface of the water.

How do they clean up the oil from the water?- Place booms around the tanker that is spilling oil. To contain and absorb any oil that flows around it.

-Sorbents are sponges that can collect the oil.

-An airplane or boat can spray chemicals into the ocean. The chemicals can break down the oil into the ocean. (just like when you dump dish soap into a sink with greasy water. The soap disperses the soap)

- They can burn freshly spilled oil but this method causes air pollution

Density UnitsDensity Units Mass = grams (g)

Volume = cubic centimeters (cm3) or millilitres (ml)

Density = g/ml or g/cm3

We can calculate density using the formula:

Density = Mass / Volume

p = m / V

QuestionQuestion: Which block has a higher density?(**remember that Density = Mass/Volume*)

Block 1: Block 2:

Mass = 79.4 g Mass = 25.4 g

Volume=29.8 cm3 Volume = 29.8 cm3

Block 1: Block 2:Mass = 79.4 g Mass = 25.4 gVolume=29.8 cm3 Volume = 29.8 cm3

*** Density = Mass / Volume p = m / V

Block 1: p = m = 79.4 g = 2.66 g/cm3

V 29.8 cm3

Block 2: p= m = 25.4 g = 0.85 g/cm3

V 29.8 cm3

Therefore Block 1 is made of a denser material than block 2.

Determining the volume of a geometric object

• In order to find the volume of a geometric object simply multiply its height by its width by it length

• Example : The volume of a rectangular prism with a height of 2 cm, a width of 3 cm and a length of 7 cm is:

• 2 cm x 3 cm x 7 cm = 42 cm3

Determining the volume of an irregularly shaped object

• Example: A rock

• What do we find the volume of a rock?

• Using water displacement.

• Example: Put a rock in beaker filled with water and you will see the water rise. Whatever amount of water that rose is the volume of the rock.

MM

p x Vp x V

Using the “Density Triangle”

M

d x V

DensityDensity:: We cover the We cover the pp and use and use M M V V

p = p = MM V V