10/15/201 5 Starter : 10/15/201 5 67 68 Density Density Practice: Glue notes here Connection: Density Ws Exit: Jake has a book, a ruler, and a balance. How can Jake find the density of the book with the tools Application : Do the Practice Density Problems here EQ: How can density be measured or quantified? Ms. Kraft found a cube with the following measurements: L=3cm W=5cm H=4 cm. What is the volume of the cube? The cube has a mass of 162 g. How does this relate to density?
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10/15/2015
Starter:
10/15/2015
67 68
Density Density
Practice: Glue notes here
Connection: Density Ws
Exit:Jake has a book, a ruler, and a balance. How can Jake find the density of the book with the tools he has?
Application : Do the Practice Density Problems here
EQ: How can density be measured or quantified?
Ms. Kraft found a cube with the following measurements: L=3cm W=5cm H=4 cm. What is the volume of the cube? The cube has a mass of 162 g. How does this relate to density?
Agenda 1. Starter
2. Density Notes3. Exit
Date Lecture/ Activity/ Lab Page8/29/ Syllabus /Notebook Guidelines 1-28/29 Periodic Table/ Formula 3-48/29 Tools/ Measurement 5-68/29 Lab Report/ Investigations 7-88/30 Safety equipment 9-108/31 Flow of energy vocabulary 11-129/4 Matter, Metals, Nonmetals, & metalloids 13-149/5 Lab- Physical Properties 15-169/6 Density 17-18
Table of Contents
Calculating Density
DensityWe know that matter is anything
that occupies a space and has
mass.
Density is the amount of matter there is in a given space.
ExamplesMetal vs. Wood
Metal
Wood
Water vs. Oil
Water
Oil
The amount of particles there are in the metal and water that occupies the space provided is a lot more than the amount of particles present in the oil and wood in the same amount of space.
Water and metal are more dense.
What do we use density for?
Density is one of the basic ways to measure and compare the physical properties of different matter
Which one is more dense?
People in a square (popular place vs. not popular place)
How about this: Which square is more dense?
A B
• Do they occupy the same volume?
• Do the have the same amount of particles?
Which one is more dense?
Now which one is more dense?
• Do they occupy the same volume?
• Do the have the same amount of particles?
B
A
A is more dense because for the small volume it holds, it has more matter.
Even though they have the same amount of particles, if A was the same size as B, A would have 4 times as much particles.
B
A A A
A A
What is density?
To find density, the amount of mass is divided by the volume of the substance.
Density = mass OR mass ÷ volume.
volume
Mass is measure in grams and kilograms.
Volume is measure in cubic centimeters or cubic milliliters.
MassGrams is represented as a g Kilograms is represented as a kg
VolumeSolid -------Cubic centimeters = cm3
Liquid ------ milliliters = mL
1mL = 1cm3
ALWAYS REMEMBER
UNITS!
So if Density = mass volume
Density = g or g cm3 mL
SI Units: International System of UnitsModern metric system, measurements
MassGrams = gKilograms = kg
LengthMeter = mMillimeter = mm
LiquidLiters = LMilliliter = mL
ALWAYS REMEMBER
UNITS!
SI Units: continued
Time Seconds = s Milliseconds = ms
ConversionsMilli = m __centi= c __Kilo = k __
ALWAYS REMEMBER
UNITS!
Frank measured an eraser. He used a balance to measure the mass at 4g. However Frank is having trouble finding the volume. Can you help him?
l = 5cmw = 1cm
h = 2 cm hwlV
Given:
Formula
Solve:
Answer:
L = 5 cmw = 1 cmh = 2 cm
hwlV
V = 5 cm x 1 cm x 2 cm
= 10 cm3
10 cm3
ALWAYS REMEMBER
UNITS!
Let’s try a density problem together
Frank has a paper clip. It has a mass of 9g and a volume of 3cm3. What is its density?
Given: D = m = V = Formula:
Solve:
Answer: V
mD
?
9 g
3 cm3
D = m / V
= 9 g / 3 cm3
= 3 g / cm3
3 g / cm3
ALWAYS REMEMBER
UNITS!
Frank also has an eraser. It has a mass of 4g, and a volume of 2cm3. What is its density?
Given:
Formula
Solve:
Answer:
V
mD
D = ?
m =4 g
V =2 cm3
D = m / v
= 4 g / 2 cm3
= 2 g / cm3
2g / cm3
ALWAYS REMEMBER
UNITS!
Work on these problems with your neighbor.
Jack has a rock. The rock has a mass of 6 g and a volume of 3 cm3. What is the density of the rock?
Jill has a gel pen. The gel pen has a mass of 8 g with a volume of 4 cm3. What is the density of the rock?
2 g / cm3
2 g / cm3
Now, try these on your own.
Alicia has a watch. It has a mass of 4 g and a volume of 2 cm3. What is the density of the watch?
Mia has a wallet. It has a mass of 15 g and a volume of 5 cm3. What is the density of the wallet?
2 g / cm3
3 g / cm3
To actually calculate density we need measuring instruments.
If we use a scale, we measure the weight of the object. The weight is the force due to gravity pulling down.
You weigh less on the moon because gravity is less. But the amount of particles you are made of doesn’t change.
So to measure the mass, we need to use a balance
Only mass is measured by the balance because the object’s mass counteract with the weights on the balance.
Measuring the volume of an object can be very tricky as well.
Most objects are not regular shapes that we have formulas for to calculate the volume. Such as:
In real life, most objects only resemble these shapes.
Most objects are odd shaped.
It is almost impossible to accurately calculate the volume of most objects.
That’s where volume by displacement comes into play.
When you think of displacement, what do you think of?
The object takes a certain amount of space.
The water particles rises to a new final volume.
The difference in the water levels from before and after will give you the volume of the object.
In volume by displacement, the displacement of water or any other liquid is involved.
In a graduated cylinder, we measure the initial volume of water.
Then we drop our object in.
V1 VF
The equation for volume of displacement
Object Volume =
Water Volume After – Water Volume Before
75-mL – 50-mL = Object’s volume 25-mL = Object’s volume
What is the volume of this object?
Vo= ?
Vf =
Vi =
Vo =
Vo =
9 mL
7 mL
9mL – 7mL
2mL
Measuring AccuracyWhen measuring Volume of liquids we
use the:
Meniscus: Bottom arch water of used for measuring volume.
Liquid Layers
If you pour together liquids that don’t mix and have different densities, they will form liquid layers.
When liquids don’t mix that means they are Insoluble
Liquid Layers
The liquid with the highest density will be on the bottom.
The liquid with the lowest density will be on the top.
Liquid Layers
Which layer has the highest density?
Which layer has the lowest density?
The green solution
The yellow solution
Liquid Layers
Imagine that the liquids on the left have the following densities:
A. 10g/cm3 C. 3g/cm3
B. 6g/cm3 D. 5g/cm3
Which density would go with which layer?
A
B
D
C
Liquid Layers – Try with your neighbor
Which liquid has the highest density?
Which liquid has the lowest density?
Which liquid has the middle density?
The Golden Syrup
The Oil
The Water
Liquid Layers – Try on your own!
Imagine that the liquids on the right have the following densities:
15 g / cm3 10 g / cm3
3 g / cm3 9 g / cm3
7 g / cm3 12 g / cm3
Match the colors to the correct densities.
3g/cm3
7g/cm3
9g/cm3
10g/cm3
12g/cm3
15g/cm3
10/15/2015
Starter:
10/15/2015
67 68
Density Density
Practice: Glue notes here
Connection: Density Ws
Exit:Jake has a book, a ruler, and a balance. How can Jake find the density of the book with the tools he has?
Application : Do the Practice Density Problems here
EQ: How can density be measured or quantified?
Ms. Kraft found a cube with the following measurements: L=3cm W=5cm H=4 cm. What is the volume of the cube? The cube has a mass of 162 g. How does this relate to density?
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