Download Density Test Review

Density Test
Review
Standard II: Objective 1
 What
is the density of a log that is floating
in a lake?
 It is less dense than water and denser
than the air above it.
 A rock and a lead weight both sink when
dropped into a lake. What do you know
about their densities?
 They are both denser than air and water.
 Water
has a density of 1g/mL. What
density might a typical rock have?
 5g/mL
Substance
Oil
Water
Plastic
Marble
Aluminum
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Density
.8 g/mL
1.0 g/mL
.9 g/ cm3
4.2 g/ cm3
2.3 g/ cm3
When poured together in a jar, what would
be the order of the substances starting from
the bottom of the jar and going up?
Marble, Aluminum, Water, Plastic, Oil
If these substances were all placed in a test
tube together, where would a substance with
a mass of 14 g and 20 mL float?
You must first do the math to find the density.
On top of the oil
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How would a student find the volume of an
irregularly shaped piece of rock?
By water displacement… find the volume of a
liquid, add the rock, count the change in
volume. That’s the volume of the rock. This
method is called water displacement.
If the volume of a rock is 8 cm3 and its mass is
16g, what is its density?
Mass/volume=2g/cm3
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Why is finding the density of gasses difficult?
Because it is difficult to contain them AND
finding the mass is difficult because gasses
don’t have a lot of mass so you need sensitive
equipment.
A student collected data about the density of
air. She found that .1g of air had a volume of
100cm3. What is the density of air?
Mass/volume=.001g/cm3
A
rock dropped in a graduated cylinder
raises the level of water from 20 to 35 mL.
The rock has a mass of 45 g. What is the
density of the rock?
 You must first find the volume which the
difference between 35 and 20=15 mL.
Then calculate density by dividing mass
by volume mass/volume=3g/mL.
A
liquid is found to have a volume of 75
mL in a graduated cylinder. When
placed on a balance the liquid and the
graduated cylinder has a mass of 125 g.
The empty cylinder has a mass of 50g.
What is the density of the liquid?
 Find the mass by subtracting the mass of
the empty container from the mass of the
filled container. Mass=75 g.
Mass/volume=1g/mL
A
liquid has a density of 1g/mL. If you
have 50 mL of the liquid, what would its
mass be?
 1 g/mL means for every mL there is one
gram of substance. So if there’s 50 mL
you multiply that number to the number
of grams and you have the total mass for
the amount of volume.
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A square chunk of plastic has a length of 5
cm, width of 5 cm and a height of 5 cm. It
has a mass of 200g. What is its density?
You must first find the volume by multiplying
length, width and height which =125cm3.
Mass/volume=1.6g/cm3
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Water is added to a jar with soil and gravel in
it and the jar is shaken. Draw what will
happen after the jar sits for a few minutes.
Use dots to show particle size.
A
student shakes a jar with a mixture of
sand and gravel types. Instead of mixing,
the sand grains separate into layers.
Why?
 Because they are different sizes.
Students mixed sand, gravel, clay and
humus in a jar with water and shook it.
The substances settle in the jar as
pictured below.
 Why
did the gravel
settle first?
Because it’s large
If this were a river, which
Sediment would wash
Away first?
Humus because it suspends in water easily
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In the spring, rivers in Utah are often brown in
color because they contain very small
particles of sediment called silt. Why is silt
suspended in the water?
The water is moving a lot and silt particles are
so small they float in water easily.
In winter, a layer of cold air settles in the
valleys and warmer air is often found higher in
the mountains. What might account for this
condition?
Cold air is denser than warm air.
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A beach is composed of particles of sand of
the same size. Why doesn’t the beach have
materials of all sizes? The particles have …
Been sorted by size and density.
A streambed contains round rocks, all about
the same size. Why are there no smaller
particles of sand and clay. Sand and clay…
Have washed away
A
gold miner shakes a mixture of mud and
water in a gold pan. He looks for gold at
the bottom. Why?
 Gold is very dense and sinks.
 In an experiment, a student shakes jars of
water with soil and rock in them. What
does the shaking model in nature?
 This models a stream current.
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Which question would help a student learn
more about the behavior of materials in a
mixture?
What happens to soil after a landslide?
The study of a lake shows that an incoming
stream deposits larger particles as it enters the
lake and smaller ones in the center of the
lake. What inference can be make from
these observations?
The particles are being sorted by size.
Standard II: Objective 2
 Earth’s
interior is divided into layers. What
are the four divisions, in order, of least
dense to most dense?
 Crust, mantle, outer core, inner core
 The mantle is a layer of Earth. What is its
density compared to other layers?
 It is denser than the layers above it and
less dense than the layers below it.
 Which
layer of the Earth is most dense?
 The inner core
 Why is air less dense than Earth’s rocks?
 Air is less dense because the molecules
are farther apart in air than in rocks.
 How does density affect the organization
of Earth?
 The densest material is closest to the
center, causing layers.
 Earth’s
rigid crust floats on the hot, plastic
material of the mantle. What conclusion
should be made about their density. The
crust is…
 Less dense and floats, it doesn’t matter if it
is a solid. Wood is a solid and it floats on
water because it is less dense.
From Earth’s surface to its center, the layers of
Earth’s interior differ in their composition,
temperature and pressure. This diagram
shows the layers.
What conclusion can you make about the
density of Earth layers from the diagram?
 As temperature and pressure
increases, density increases.
 Which layer is densest?
 The inner core is densest.
 Why is the atmosphere above the
crust?
 Air is less dense than the crust
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How are the materials making up the core different
from those of the crust?
They are more dense
The following materials are available to build a
model of Earth: Clay, a hard ball, aluminum foil,
cotton balls, cardboard
Which substance would be the best model for the
mantle?
Clay because it can be molded and change shape
like the mantle is a plastic liquid so is clay
Which substance would best model the thickness of
the crust?
Aluminum foil
A
collection of rocks is used to model the
kinds of materials found in Earth. Which
rock should be labeled “core” rocks?
 The rocks made of iron/nickel
 Which model of Earth shows the most
accurate shape and relative size of the
continents? A road map, a
topographical map, a globe, a poster?
 A globe shows relative size the best.
 Which
parts of this model are accurate?
 The names of the layers
 How could the crust be more accurately
represented?
 It needs to be thinner and
flattened out.
 THE
END