Properties and Changes of Matter- Comp. Sci. 3
Mrs. Bloch
8-1 Measuring Matter
Vocabulary
Weight- a measure of the force of gravity on an object
Mass- the amount of matter in an object
International System of Units- a system of units used by scientists to
measure the properties of matter
Volume- The amount of space that matter occupies
Density- a measure of the mass of a material in a given volume
My Planet Diary pg. 290
Field Trip - Travel to the eastern coast of Africa and you will find the
country of Djibouti. There, you can visit one of the saltiest bodies of
water in the world. Lake Assal is ten times saltier than the ocean. Its
crystal white beaches are made up of salt. While on your visit to
Lake Assal, be sure to take a dip in the clear blue waters. Take a
book or magazine with you to read. Wait, what? Take a book into a
lake? It might seem strange, but bodies of water with high salt
contents, like Lake Assal or the Dead Sea in the Middle East, allow
you to float so well that it's nearly impossible to sink below the
surface of the water.
Communicate - What water activities
might be easier to do in Lake Assal’s
salty water?
What activities could be more difficult?
What Units Are Used to Express Mass and
Volume? Pg. 291
Weight is a measure of the force of gravity on an object. Weight
varies with location in the solar system. A more massive object will
exert a greater gravitational force, so the weight of an object on
that more massive planet or moon will be greater. Weight is
measured with a scale.
Mass is the amount of matter in an object. It does not change with
location. Mass is constant. For this reason, scientists prefer to
describe matter in terms of mass rather than weight.
Measuring Weight – figure 1 pg. 291
Use the weight of the first scale to estimate the weight of the fish on the
other scales.
1. Estimate – Use the weight of the first scale to estimate the weight of the
fish on the other scales. Draw in the pointers.
2. Describe- How would their weight change on a small planet like
Mercury? Or a large planet like Neptune? _______________________
____________________________________________________________
The International System of Units or SI pg. 292
To measure the properties of matter, scientists use the
International System of Units, or SI. The SI unit of mass is the
kilogram (kg). If a smaller unit of mass is needed, the gram (g)
is used. There are 1,000 grams in a kilogram or 0.001
kilogram in a gram.
Measuring Mass – Figure 2- pg. 292
The SI system uses grams and kilograms to measure mass.
1. Calculate – In the table,
convert the mass of
each object from grams
to kilograms.
2. Challenge- Suppose you are
taking a flight to Europe. You
are only allowed a 23-kg
suitcase. How much is that in
pounds? (Hint: 1kg = 2.2 lb)
o 50.6 lb
o 46.2 lb
o 10.5 lb
Volume pg. 293
Another measurable property of matter is volume, or the amount of
space matter occupies. The SI unit of volume is the cubic meter
(m3). Other common SI units of volume are the cubic centimeter
(cm3), the liter (L), and the milliliter (mL).
There are 1,000 milliliters in a liter or 0.001 liter in a milliliter. One
milliliter is the same volume as 1 cm3. The volume
of a rectangular solid is calculated according to the following
formula.
Volume = Length x Width x Height
Calculating Volume – Figure 3 pg. 293
What is the volume of the suitcase?
Suppose you want to know
The volume of a rectangular
Object, like one of the suitcases
Shown in figure 3. First, measure
The length, width, and height
(or thickness) of the suitcase.
Then, multiply the measurements
Together.
Volume = Length x Width x Height
When you multiply the three measurements, you
Must also multiply the units.
cm3 = cm x cm x cm
Find the volume of the suitcase. _______________________
Measuring Irregular Objects pg. 293
One way to measure the volume of
an irregular object is to submerge
it in liquid in a graduated cylinder.
The water level will rise by an
amount that is equal to the
Volume of the object in milliliters.
Assess Your Understanding pg. 293
1. Describe- Why is mass more useful than weight for measuring
matter?
_______________________________________________
_______________________________________________
I get it! Now I know that the SI unit for mass is ______________
the SI unit for volume is ____________
Calculating Density pg. 294
Density is a measure of the mass of a material in a given volume.
Density is expressed as the number of grams in one cubic
centimeter, or g/cm3. Because one milliliter is the same volume as
one cm3, density can also be expressed as g/mL. You can
determine the density of a sample of matter by dividing its mass
by its volume.
How Is Density Determined? Pg. 294
The density of water is 1 g/mL, or 1 g/cm³. Objects with greater
densities will sink. Objects with lesser densities will float.
Density is a physical property of a substance. It can be used
to identify an unknown substance.
The Formula to find Density is:
1. Apply Concepts- Liquids can form layers based on density.
Which colored layer of liquid represents
Water: 1.g/ml, Honey: 1.36 g/ml, Dish Soap: 1.03 g/ml,
Corn Syrup: 1.33 g/ml, Vegetable oil: 0.91 g/ml?
- Find and circle the median density.
2. Calculate- What is the density of a liquid with a mass
of 17.4 g and a volume of 20 mL? Where would this
liquid be in the column?
3. Explain why the liquid with the median density floats
where it does.
Using Density- Virtual Lab- Figure 4 pg. 295
Density can be used to identify substances.
Estimate- Hypothesize which rock sample is gold. Then calculate
the density of each sample. Circle the rock that is real gold.
My hypothesis is that the gold rock is
o A
o B
o C
A : Mass = 108 g Volume = 12 cm3 Density = _______
B: Mass = 126 g Volume = 15 cm3 Density = _______
C: Mass = 386 g Volume = 20 cm3 Density = _______
Assess Your Understanding pg. 295
2a. Identify – Maple syrup will (float / sink) in water because its
density is greater than 1 g/cm3.
b. Calculate - What is the mass of a sample of a substance with
a volume of 120 mL and a density of 0.75 g/mL?
___________________________________________________
c. Challenge – Liquid water and ice are the same substance,
H20. How would you explain why ice floats in water?
___________________________________________________
_________________________________________________
I get it! Now I know density is calculated by _________________
___________________________________________________
_________________________________________________