Density, Mass, & Weight

1. Density, Mass, & Volume
Concepts & Equations
Mr. Abud

2. Mass
•Measurement of the amount of matter, or
stuff, an object has
–Measured in grams (g)

3. Volume
•Measurement of the amount of space an
object takes up
–Measured in milliliters (mL) or cm
3

4. Volume of a regular shaped object
•Rectangular Prism
–Length x width x height
•Cylinder
–Area of circular base (pi x radius
2
) x height

5. Density
•Measurement of the amount of mass an
object has per its volume
–Derived unit:g/mL
•Comes from units of mass per units of volume

6. Density as a ratio
•Density can be viewed as the ratio of an
object’s mass to its volume
Mass : Volume

7. Graphing Density
•On the vertical, or y-axis, mass is plotted
•On the horizontal, or x-axis, volume is
plotted
•The resulting line that comes from plotting
coordinates on the graph represents the
density

8. 1cc = 1mL

9. Remember Slope?
•Rise over run
–It’s the amount that a y value changes
compared to how much an x value changes
•It’s a ratio of y values to x values

10. Slope of Mass v Volume
•If we figure out how much the mass
changes (∆) compared to how much the
volume changes, we get a slope that is a
ratio of mass to volume
–That slope will look like this:
∆Mass
∆Volume
THAT’S DENSITY!!!!!

11. Density Equation
•Density = mass divided by volume
•g/mL = g divided by mL
Let’s use density!

12. dv
m
D = m / v

13. How to use
the circle
•Using info from problem,
determine what you are
trying to find.
•Cover up the variable
you’re trying to find
•Do the calculation that’s
left.
EXAMPLE:
Covering up mass
leaves density x volume
dv
m

14. Problem 1
The mass of a silver bracelet is 2.5
grams, it occupies a volume of 48cm
3
,
what is its density?

15. Problem 2
The density of silver (Ag) is 10.5 g/cm3.
Find the mass of Ag that occupies 965
cm3 of space.

16. Problem 3
A 2.75 kg sample of a substance occupies
a volume of 250.0 mL. What is its density?

17. Problem 4
A rectangular block of Lead (Pb)
measures 20.0 mm X 30.0 mm X 45.0
mm. If the mass of the Pb block is 10g,
find its density.

18. Problem 5
A cube of gold (Au), which has all equal
sides, has a side length of 1.55 cm. If the
sample is found to have a mass of 71.9 g,
find the density of Au.

19. Measuring Volume INDIRECTLY
•Some objects are irregularly shaped
–So it’s hard to find out their volume
•We need a method of getting their volume
though.
–INDIRECT MEASUREMENT
•Water displacement
•Put an irregular shaped object in water,
measure how much the water rises, and
that’s the object’s volume

20. Ways to Affect Density
•Change mass AND keep volume same
•Change volume AND keep mass same

21. Change Mass AND Keep Volume Same
•Increase the mass  increase density
•Decrease the mass  decrease in density
Which container has more density?
A B

22. Change Volume AND Keep Mass Same
•Increase the volume  decrease density
•Decrease the volume  increase density
Which container has more density?
A B

23. What 2 ways will INCREASE density?

24. What 2 ways will INCREASE density?
Keep the
same
mass AND
decrease
the volume
Keep the
same
volume
AND
increase
the mass

25. Comparing Densities
•Objects or substances with MORE density
will sink below objects or substances with
LESS density
–Which do you think is MORE dense,
Water or Oil???

26. Water, Oil…and a Superball
The oil is less dense than the water, so it’s on top. The superball
is less dense than water, but more dense than oil, so it sinks to
the bottom of the oil layer, yet floats on the top of the water layer.

27. In Conclusion
•If you have 2 substances,
–the MORE dense substance will be on bottom
–The LESS dense substance will be on top

28. Think About This
•The density of five liquids are measured
as follows:
–Liquid 1: 1.0 g/mL
–Liquid 2: 1.38 g/mL
–Liquid 3: 0.77 g/mL
–Liquid 4: 2.95 g/mL
–Liquid 5: 0.056 g/mL
•Draw a picture of all 5 liquids in a test tube
how they would layer according to density

29. Think About This
•The density of five liquids are measured
as follows:
–Liquid 1: 1.0 g/mL
–Liquid 2: 1.38 g/mL
–Liquid 3: 0.77 g/mL
–Liquid 4: 2.95 g/mL
–Liquid 5: 0.056 g/mL
•Draw a picture of all 5 liquids in a test tube
how they would layer according to density
Liquid 5
Liquid 3
Liquid 1
Liquid 2
Liquid 4

30. Until the Density
DUnK!!!!!!!