1. Density. What would take up more space. A kilogram of feathers…
Density! What would take up more space??? A kilogram of feathers….. or a kilogram of steel??
ROCKS - pass around OR

2. Another way to say it is, density is the measure of how ‘tightly packed’ a material
How close the atoms or molecules are to each other
NOT “heaviness” - density includes how much space an object takes up!!
All substances have unique densities including liquids, solids, and gases
Bread slice and compacted bread in large flask of water

3. “Compactness” or how ‘squeezed’ together
Low density not compact
Hot air balloon - Describe how a hot air balloon works. Defend your argument.
High density: compact

4. Low pressure warmer air tends to rise and form clouds because the air is less dense, High pressure systems contain air mass that will……. SINK because a colder air is MORE dense

5. Balloon and liquid nitrogen
astr.gsu.edu/hbase/thermo/balloon.html#c1
What happens to the gasses in the balloon when it is placed in liquid nitrogen? (nitrogen condensed to -196 degrees celcius)

6. What would happen???? Mercury density = 13600kg/m3 (13.6g/cm3)
Lead density =
11340kg/m3 (11.3g/cm3)
Sinking vial - make it float

7. Lead floats on liquid mercury! (so does this pool ball)

8. ICE (that’s why it floats)
Special Case:
Ice vs. water…..
Which is less dense?
ICE (that’s why it floats)
Which is why ice forms on top of lakes and floats in drinks!

9. Why is density important?
Rocks, woods, metals, everything really MUST have its own specific density
This can be used to identify things!
Beans/ping pong ball; Big jug of water in a pool
Wouldn’t you like to have a bunch of THIS dense material?

10. Archimedes and the Kings Crown: How we discovered how to measure volume of weird shaped things
250 b.c., the Greek mathematician Archimedes - story

11. Factors affecting Density
Temperature
Pressure
Which is high temperature, which is low?
Low pressure
High pressure
High Temp
Low temp
Low density
High density
Add several drops of red food color to each of two 250-mL Erlenmeyer flasks; fill them with warm tap water. (If tap water is not warm, heat some tap water on a hot plate to °C.)
Add several drops of blue food coloring to each of the other two 250-mL Erlenmeyer flasks; fill them with cool tap water.
Predict the outcome when one flask is inverted over the other.
Place a paper card on top of the vessel filled with warm water. Invert the flask making sure to hold the card in place. Stack it on top of one of the cool water flasks. Remove the card. Remain prepared to catch the flasks.
  ** Visual here.
Place a paper card on top of the flask filled with cool water. Invert the flask making sure to hold the card in place. Stack it on top of the other warm water flask. Remove the card.
Wide mouth containers may also be used.

12. Factors affecting Density
Dissolved solids – in liquids
Concentration and substance dissolved
Which is more dense salt or fresh water?

13. DENSITY! Note: 1 mL = 1 cm3 and 1L = 1000 cm3 d = mass = g or g
Density really just compares the mass of an object to its volume. This is a ratio
d = mass = g or g
Mass usually expressed in grams OR kg
Volume usually expressed in cm3 or liters, etc.
volume mL cm3
Note: 1 mL = 1 cm3 and 1L = 1000 cm3

14. Density = amount of matter per unit volume
Density is the ratio of mass to volume
If the volume stays the same and the mass increases g/2cm3 =
10g/2cm3 =
the density will increase
If the mass stays the same and the volume increases g/2cm3 =
10g/5cm3 =
The density will decrease
2.5 g/cm3
5 g/cm3
2.5 g/cm3
2.g/cm3

15. DETERMINING DENSITY LAB TIME
Regular Shapes – mass, then determine the volume by formula EX: cubes, cylinders, spheres, cones, etc.
Irregular shapes – mass, then measure displacement of a liquid (usually water) by that irregularly shaped object
Use a graduated cylinder
Add water to a predetermined level - record.
Gently drop in the irregularly shaped object.
Read the graduated cylinder – record.
Subtract the first water level from the second – this is the volume
LAB TIME

16. Algebra! formula’s best friend.
Here are some simple rules.
1. For any equation/formula both sides of the = sign must stay equal.
2. Whatever you do on one side of the = sign you MUST do on the other.
3. Whatever function x + ÷-is being applied to the variable you must do the opposite to get rid of it X is the opposite of ÷; + is the opposite of -
Lets solve for the 3 variables in density.

17. (If you are lost in algebra) The “DMV” Triangle for Volume, Mass, and Density
÷ ÷
d X V
Density = m V
Volume = m d
Mass =
d x V
Memorization will allow you to answer a few questions
Understanding the rules of algebra will let you answer millions of them!

18. How do you predict sinking or floating?
If the density is greater than the substance you put it in…
It sinks
If density is less than the substance…
It floats!
Float
SINK or FLOAT
In Water
Float
Sink
Sink
Sink
Density WS
(alcohol)
Float
(fuel)
Float