1. Density!!!

2. What is Density?
The density of a material is defined as its mass per unit volume.
So what does that mean??
How heavy something is in comparison to its size

3. What are the Units? The proper SI unit is kg/m3
We typically use g/mL or g/cm3
Remember 1mL = 1cm3
How do we find mass?
How do we find volume?

4. How does Density affect us?
In general, density can be changed by changing either the pressure or the temperature.
Increasing the pressure will increase the density of a material.
Increasing the temperature usually decreases the density

5. So what does Density have to do with the Titanic?
When it hit the iceberg, it ripped open and the bottom filled with water
mass changed but not the volume

6. ***Salt water is more dense so it makes it easier for us to float****
Why else is Density important to us? It helps us to float!!! This is called Buoyancy
***Salt water is more dense so it makes it easier for us to float****
Density of water = 1 (100grams / 100ml of water) Density > 1 = sink Density < 1 = float

7. Practice with Density Density of water = 1
Buoyancy = density less than or = 1
Rock has a mass of 10g and a volume of 5 mL
Sinks
Wood has a mass of 10 g and a volume of 20 cm3
Floats
To change Density, change the Volume!!!
Air Craft carriers

8. Demo #1: Pepsi Challenge
PREDICT: Which of the following drinks will float in the water? (in, not on top)
Record your observations (you may make sketches) and provide an explanation for what took place in this demo. Be specific and include any change in the density (mass and volume) of the resulting mixture.

9. Demo #2: WHAT IS ?
PREDICT: When 25 mL of isopropyl alcohol and 25 mL of water are combined, what will be the resulting volume?
Record your observations (you may make sketches) and provide an explanation for what took place in this demo. Be specific and include any change in the density (mass and volume) of the resulting mixture.

10. Demo #3: WHATEVER FLOATS YOUR BOAT
PREDICT: Will aluminum foil (D = 2.7 g/cm3) sink or float when placed in water? Record your observations.
PREDICT: How can aluminum foil be altered to cause it to float? Record your observations.
Record observations and explain what happens as more mass is added to the foil.