density lab overview
Post on 21-Jun-2015
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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.
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 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
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