Physical Science
Ms. Hanna

substances.
2. Properties may be used to separate a mixture into its components.

materials and can be separated by physical means.
Example: How do you separate spices from iron filings?
Use a magnet to pull out the iron filings into a separate pile
Ex: How can you separate salt water into salt and water?
Boil off the water into vapor and you are left with salt
Or
Use filtration paper to hold the salt molecules apart from the water

3. Physical Properties dissolve in another substance
A. Solute-Substance being dissolved (sugar, salt, kool-aid)
B. Solvent-Substance doing the dissolving (water)
What can affect solubility?____________,
_________________________, ___________

B.
• A force of attraction and repulsion when electrical fields line up

•
The ends of a magnet are called its POLES
• The strongest poles
(N & S)
• Opposites attract & Likes repel
Poles CANNOT be separated!!!

•
A region around a magnet where the force is the strongest
N S
The strength of the field decreases as the distance from the field increases.

N S N S
S N N S

•
A magnet is no longer a magnet
• The domains are not lined up anymore
1) Heating
2) Dropping
3) Other Strong Impact

C. Density is a comparison between an objects mass and it's volume .
Mass = The amount of matter in an object.
Weight: A measure of the pull of gravity on an object.
Volume: The amount of space an object takes up.
Density = Mass ÷ Volume
Ex.The mass of an object is 25grams. The volume of an object is 5 cm3. What is its density?
F: D=M/V
S =25g/5cm3
A = 5 g/cm3
Archimedes Principle https://www.youtube.com/watch?v=ijj58xD5fDI

Molecular structure of :
Metal Wood Plastic
• The more tightly packed the molecules are the more dense the object is
• Therefore metal is the most dense
Example: Density cube lab

What is the density of an irregular object?
• You must use a graduated cylinder
• The units are not cm 3 they are ml or L
Ex. what is the density of a hammer that has a mass of
235 g?
F: volume = Total volume - liquid
S: 69ml – 65ml
A: 4ml
F: density = mass/volume
S = 235 g/ 4 mL
A = 58.75 g/mL

If you had two rods the same size (volume), but one was made up calcium and the other one made of sulfur which one would have the greater density?
Their molecule size is seen below.
• The density of sulfur is about 2 g/cm3 and the density of calcium is about
1.5 g/cm3.
• You can pack more sulfur molecules into the same amount of space

How can you tell if an object will float or sink?
You need to know the density of water
What water has the greater density? The beaker full of water or the beaker filled with one eye dropper of water?
They are the same.

• Look at your values for density in your chart.
Does the density of the different volumes of water seem to be about the same?
Yes
• What do you think is the density of water in g/cm 3 ?
1 g/cm 3 or 1g/ml (both the same)

3) Using the data from your chart, graph the volume and mass for 100 mL, 50 mL, and 25 mL.
4) Look at the graph you made.
If you measured 40 milliliters of water, what do you think its mass would be? What would its density be?
Volume: 40 mL
Mass 40 g
Density 1 g/ml
5) Choose any volume of water between 1 and 100 milliliters.
Based on the graph, what would its mass be? What would its density be?
Volume _________
Mass ___________
Density _________

• The density of a liquid determines whether it will float on or sink in another liquid.
• A liquid will float if it is less dense than the liquid it is placed in.
• A liquid will sink if it is more dense than the liquid it is placed in.
• Water has a density of 1 g/ml or 1 g/cm 3
Will it float, neither float nor sink, or sink?

• The density of a liquid determines whether it will float on or sink in another liquid.
• A liquid will float if it is less dense than the liquid it is placed in.
• A liquid will sink if it is more dense than the liquid it is placed in.
• Water has a density of 1 g/ml or 1 g/cm 3
Will it float, neither float nor sink, or sink?
Float

• The density of a liquid determines whether it will float on or sink in another liquid.
• A liquid will float if it is less dense than the liquid it is placed in.
• A liquid will sink if it is more dense than the liquid it is placed in.
• Water has a density of 1 g/ml or 1 g/cm 3
Will it float, neither float nor sink, or sink?
Float
Float

• The density of a liquid determines whether it will float on or sink in another liquid.
• A liquid will float if it is less dense than the liquid it is placed in.
• A liquid will sink if it is more dense than the liquid it is placed in.
• Water has a density of 1 g/ml or 1 g/cm 3
Will it float, neither float nor sink, or sink?
Float
Float
Neither

Hypothesis: I believe that raisins will __float/sink_ in soda because they have a _ _greater/lesser density than soda.
1) Pour clear soda into a medium size beaker and add some raisins (fresh).
Observations: What happens??
2) At first what had the larger density, the soda or the raisins?
____________________
(Think about it..if the raisins float they are _____ dense than water. If the raisins sink, they are _____ dense than water)
3) After a minute, which had the larger density?
______________________________

4) Why do the raisins appear to be dancing?
5) What happens when raisins are put into hot soda? Explain why

What is the most dense? Label the picture below.

What is the most dense? Label the picture below.
Least
Dense
Most
Dense

Can you change the density of water? Why do boats float?
buoyancy: arises from the fact that Fluid Pressure increases with depth and from the fact that the increased pressure is exerted in all directions
( Pascal's principle ) so that there is an unbalanced upward force on the bottom of a submerged object Buoyant force opposes the force of gravity
Do the piece of aluminum sink float activity

What has a greater density, salt water or fresh?
Draw a carrot slice in each of the cups below to reflect your observations

1)Will a boat float higher or lower in the ocean?
Higher
2) How does adding salt change the density of the water?
It increases the mass of the water therefore increasing its density
3) What would you expect if you placed equal volumes of water and saltwater on opposite ends of a balance?
Salt water would weigh more
4) Adding salt to water increases both its mass and volume; which do you think it increases more, the mass of the water or the volume?
Mass, if the volume increased the carrot would have sunk to the bottom

REAL LIFE EXAMPLES OF BUOYANCY IN ACTION
Ex. Swim bladders in fish
• swim bladder has an air bubble in it
• Relax their muscles --> sac increases in size --> displaces more water --> Fish floats to surface
• Contracts their muscles --> sac decreases in size --> displaces less water --> Fish sinks to bottom

Ex. Ballast tanks in submarines
• Decreasing water in the ballast tanks--> causes the submarine to surface
• Increasing water in the ballast tanks --> causes the submarine to submerge

CARTESION DIVER
Bill Nye-Buoyancy http://www.schooltube.com/video/7100de854a0a40fead91/Bill%20Nye%20-%20Buoyancy

• Complete the hypothesis under “Can temperature change the density of a liquid?”
• Hypothesis: What is more dense? Cold or warm water?
• Watch the video to answer the questions
• www.middleschoolchemistry.com/multimedia
/chapter3/lesson6#hot_water_on_cold water

Can temperature change the density of a liquid??
Be sure to label the areas of cold and hot water.
Is cold water more, less, or the same density as room-temperature water?
More Dense
Is hot water more, less, or the same density as room-temperature water
Less Dense

Look at the model of water molecules in the diagram below to help you compare the volume, mass, and density of cold and hot water.

Write more, less, or same in the chart to describe the volume, mass, and density of cold and hot water compared to room temperature water.

Write more, less, or same in the chart to describe the volume, mass, and density of cold and hot water compared to room temperature water.
Less More

Write more, less, or same in the chart to describe the volume, mass, and density of cold and hot water compared to room temperature water.
Less
Same
More
Same

Write more, less, or same in the chart to describe the volume, mass, and density of cold and hot water compared to room temperature water.
Less
Same
More
More
Same
Less

• Spend about 5 minutes completing the last part of the notes on your own
• Spend 2 more minutes comparing answers with your seat partner (lab seats can pair up)

Why does cold water sink in room-temperature water?
the molecules in cold water are just a bit closer together, which slightly decreases its volume. This slight decrease in volume leads to an increase in density
Why does hot water float on room-temperature water?
the molecules in hot water are just a bit further apart, which slightly increases its volume. This slight increase in volume leads to a decrease in density

Can temperature change the density of a liquid??
• Heating a substance causes molecules to speed up and spread slightly further apart, occupying a larger volume that results in a decrease in density. (Mass stays the same)
• Cooling a substance causes molecules to slow down and get slightly closer together, occupying a smaller volume that results in an increase in density.
• Hot water is less dense and will float on roomtemperature water.
• Cold water is more dense and will sink in roomtemperature water.