Investigation 5
 Part
1
 Demo
Bottles
 Draw these two bottles in your journal and
label the page Density Demo Bottles
 What is happening?
 Can you explain why the liquids behave the
way they do?
 We’ll come back to these bottle after we
investigate the behaviors of liquids when
they are put together. Leave plenty of space
in your journal for you to add more
information to this spot later.
I
have four liquids for you to investigate.
 Your challenge today is to layer all four
liquids in a section of straw without them
mixing.
4
liquids
 Straws
 Straw holder
 Pipettes – 1 per liquid – don’t mix
 Waste cup
 Paper towels
 Colored pencils
 Lab page 21
Who did it?
 Draw your solution on the whiteboard – one
person from each table.
 Color the correct solution in your journal –the
title of your page should be Density of Fluids
 What do you think caused the salt solutions to
layer in this way?
 All of the solutions are made with the same
materials, water and salt. How is it that some
salt solutions can be heavy and some light if
they are made with the same materials?

 Why
did the fluids layer like they did
yesterday?
 Did you have to have it in a certain order?
 Why?
 All of the solutions were made out of the
same materials, so why would they behave
differently?
 Let’s
take a look at these demonstration
bottles again.
 Go back to your Density Demo Bottle Page
 After doing the investigation yesterday, think
about and answer these questions.
 How are these bottles like the investigation
you did yesterday?
 How are they different?
 This
bottle has blue beads and white beads in
it.
 Draw a picture of the bottle and the beads.
 Shake it!
 Now draw the bottle again. What’s
different? Why did that happen?
 But wait, what is it doing now? Why?
 Let’s try it again…
 Explain in your journal why the stuff in this
bottle behaves the way it does
 Which
is heavier, gold or feathers? Why?
 Draw these two jars with their contents in
your journal.
 Which of these is heavier, this cup of foam
cubes or this cup of beans?
 How do you know?
 How could you find out for sure?
 The cups are the same size and they are both
full. How can one be heavier than the other?
 When
you have equal volumes of material,
and one is heavier than the other, the
heavier material is denser.
 Density is the amount of matter in a volume
of material. There is a lot of matter in a
volume of rock, steel, or gold. There is far
less matter in an equal volume of cotton,
cork, or air.
 Density
is a property of matter. All matter
has density, including all solids, liquids, and
gases. If you compare equal volumes of
matter, and one is heavier (has more mass),
the heavier volume is denser.
 In the salt-solution layering activity you
discovered how to layer all four solutions.
 Do you think density played a role in the
layering phenomenon? How?
I
need 25 ml of this color in this cup
 And 25 ml of this color in this cup
 And 25 ml of this color in this cup
 And 25 ml of this color in this cup
 Label a page in your journal like above.
 Draw and color in these two cups.
 Will these four identical volumes of salt
solutions have the same mass? If not, which
one will have the greater mass?
 Make a prediction for each color and write it
in your journal
 Weigh
each of the solutions – record their
masses in your journal.
 Is that the exact mass of the salt solution?
 What else do we have to measure?
 Write the actual masses of the solutions in
your journal.
 Which
solution is denser?
 How do you know?
 If you were to layer these solutions which
would be on the bottom and which would be
on the top – draw and color your answer in
your journal.
 Is this the same as your straw layers?
Predict the relative densities of each of the different solutions.
Your
Prediction
Red
Actual Density
25.0 g/25ml
Green
26.5 g/25ml
Yellow
28.2 g/25 ml
Blue
30.0 g/25 ml
Add these densities to Lab Sheet 21 – Liquid Layers
I
have here – two samples of salt water.
Sample 1 is 45 ml, and its mass is 54 g.
Sample 2 is 120 ml and its mass is 132 g.
Which sample is denser?
 Why?
 Density
is the ratio b/t the mass of a sample
of matter and its volume.
 The mass of a sample is the amount of stuff
in it. You find the mass of an object or
sample of material by weighing it. Mass is
measured in grams.
 Volume
is how much space a sample of
matter occupies. All matter has volume. We
measured the volume of liquids with a
graduated cylinder. Solids and gases are
measured in cubic centimeters. Cubic
centimeters and milliliters are the same.
 Density is the amount of mass per cubic
centimeter. Density can be expressed as an
equation We can use the equation to
calculate the density of anything for which
we know the mass and volume of a sample.
 Density = Mass/Volume
D = M/V
 Density
1.
2.
3.
4.
5.
= mass/volume
Density 1 weighs 54 g and its volume is 45 cc.
What is its density. Write the formula first, then
show all your math.
Density 2 weighs 132 g and its volume is 120 cc.
What is its density?
Lab Sheet 23 – Pull out Lab Sheet 21 and 23, use
the data from 21 to help you calculate density on
23 for each color.
Complete Lab Sheet 21/23 and turn in.
Homework – Density WS
 The
red solution was pure water with red
coloring. What is the density of water?
 Which solution was densest? How do you
know?
 What is the relationship b/t layering and
density?
 What happens when you try to layer a denser
solution on top of a less-dense solution?
 Pine
wood has a density of 0.60 g/cc. Will it
be a floater or sinker in water? Why?
 Styrene plastic has a density of 1.7 g/cc.
Will it be a floater or a sinker in the red
solution? Why?
 Now for the big test – explain these
demonstration bottles using your new
knowledge.
 Clue – there is water in both bottles
 The
density of any object can be calculated if you
know its volume and mass.
 Volume can be measured in milliliters or in cubic
centimeters. The unit most often used is cubic
centimeters, but ml can be used with fluids.
 Mass can be determined by weighing.
 Density is mass per unit volume.
 Always, always include units with your calculations
and answers!!!!
 We’re
going to mess with density a little more.
 Activity 1 - Pop demonstration
 Activity 2 - In this lab there are two boxes of cubes
made of different materials but all of the same
size. All of you will need to share the cubes in
order to measure the mass and volume. There are
12 cubes and four tables will share that box having
3 cubes each time.
 How will you measure mass?
 How will you determine volume?
 You
will learn to use both the triple beam
scale and the electronic scale. There will be
a quiz soon where you will be given an
object to weigh perzactly – so make sure you
are comfortable using both types.
What if you had an object like this – that is not a
perfect cube. How could you figure out it’s volume?
 Come up with a plan with your table and be ready to
share your idea.
 Use the old water volume trick –
 Now try it out – I have 8 objects up here that you are
going to determine their density. What tools do you
need?
 Complete the table – you will have a limited time to
determine the density of an object before I say PASS!
 Use your tub for water overflow issues.

Object
Volume (cm3)
Mass (g)
Density (g/cm3)
 Let’s
give you another challenge. See if you
can help Rico out.
 When you finish – turn it in and Read Pg. 2731 in your green book.
 Complete the Discovering Density Worksheet.
 Part
2
 Light
is one type of radiation we get from
the Sun.
 Radiant energy travels through space as
waves.
 Visible light, ultraviolet, and infrared
radiation are responsible for most of the
heating of Earth’s surface.
 When the Sun’s radiant energy hits Earth’s
surface, some of it is absorbed. Molecular
motion of the material increases. Molecular
motion is heat.
 Heat
can transfer from one material to
another when they come in to contact.
 The atmosphere is heated by conduction
when air molecules contact Earth’s surface,
and by reradiation from Earth’s surface.
 Heat transfers from warmer to a cooler area
or material.
 So what about heat in solids and liquids?
 In
solids, the atoms or molecules are pretty
much locked into positions in relationship to
one another. When a radiant energy is
absorbed by one area in a solid, the
molecules begin to vibrate more. The
vibration impacts neighboring molecules, and
the motion spreads. That’s how heat is
conducted through a solid material – by
vibrational energy, one molecule to the next.
 In
fluids, both liquids and gases, molecules
are not locked into position with respect to
one another. They can move toward, away
from and past one another.
 Heat can transfer from one place to another
in liquid or gas by conduction, molecules
hitting one another – and by absorption of
radiant energy.
 There’s another way, however, that energy
moves in fluids. That’s what we will observe
today.
 We
figured out how to make layers with salt
water solutions. Today is a new challenge.
Layer water – with different temperatures.
 Lab Worksheet 27 – Layering Hot and Cold
Water.
 You are going to predict and record how to
layer different water temperatures,
Fill a vial about ¾ full with room-temperature
water. I have that set out in jugs so we are all
using the same temperature.
 Use the bulb pipettes and colored water to
create three layers in the vial, red, blue, and
clear.
 Red is dang hot and blue is the water on ice.
 Go to the water station to get water as you need
it. Use the small vials for the red hot water and
cold blue water.
 Keep each vial in its own styrofoam cup to
maintain the temperatures.

 Your
third vial will be your experimental
vial. Fill it about ¾ full with the room
temperature water. Create your own layers
inside the experimental vial.
 Helps





Use the clear plastic cup for failed layering
attempts.
A piece of white paper held behind the
experimental vial will make it easier to see
layers.
Don’t jostle, move, bump, breathe on or even
touch a layering experiment in progress.
After refilling the experimental vial with roomtemperature water, wait a full minute for the
water to become still before adding colored
water.
Add old blue water to the chilled water, or red
water back to the hot water if you can.
 Write
how you accomplished your
temperature layering in your journal.
 Include these if you didn’t already write
them.



Wait for the room-temperature water to stop
moving.
Use a pipette to carefully introduce blue water
under the room temperature water.
Use the other pipette to place hot water on top
of the room-temperature water.
 Predict
what will happen if your let your
layered vial sit for five minutes or more…
 Watch
 Write down what happens – explain why that
happens.
 Complete Density WS for tomorrow.