Powerpoint Notes - Ms. Hanna's Science Class

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Unit 2: Properties of Matter

Physical Science

Ms. Hanna

Substances have characteristic properties.

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?____________,

Pressure

B.

Magnetism

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

Poles of a Magnet

The ends of a magnet are called its

POLES

The

strongest

poles

North and South

(N & S)

Law of Magnetic Poles

• Opposites attract & Likes repel

Poles CANNOT be separated!!!

Magnetic Field

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

Demagnetizing a Magnet

A magnet is no longer a magnet

• The domains are not lined up anymore

Ways to Demagnetize a Magnet

1) Heating

2) Dropping

3) Other Strong Impact

C. Density is a comparison and it's volume . between an objects mass

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.

Find the density of water

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

Do raisins have a greater density than soda?

Hypothesis: I believe that raisins will __float/sink_ a _ _greater/lesser density than soda.

in soda because they have

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?

______________________________

Dancing Raisin Demo

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--> the submarine to surface causes

Increasing water in the ballast tanks --> the submarine to submerge causes

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

Use what you know about density to answer the following questions.

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 same) in density. (Mass stays the

• 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 temperature water.

on room-

• Cold water is more dense and will sink temperature water.

in room-

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