2. Warm-up:
Why is it easier for your body to float in the
ocean rather than in your swimming
pool?
3. DENSITY:
• Intensive property – it does not depend on
the amount of matter.
• Units are g/mL or g/cm3
• Density is constant for all sample sizes of a
given substance.
4. Osmium is a very dense metal. What is its
density in g/cm3 if 50.00 g of the metal occupies
a volume of 2.22cm3?
1) 2.25 g/cm3
2) 22.5 g/cm3
3) 111 g/cm3
Practice Problem #1
5. 2) Placing the mass and volume of the osmium metal
into the density setup, we obtain
D = mass = 50.00 g =
volume 2.22 cm3
= 22.522522 g/cm3 = 22.5 g/cm3
SOLUTION
6. Practice Problem #2:
1. Calculate the density of a piece of lead
metal that has a mass of 125.2 g and a
volume of 11.0 mL.
7. Problem A piece of copper has a mass of
57.54 g. It is 9.36 cm long, 7.23 cm wide, and
0.95 mm thick. Calculate density (g/cm3).
Density mass (g)
volume (cm3)
8. Strategy
1. Get dimensions in common units.
2. Calculate volume in cubic
centimeters.
3. Calculate the density.
9. SOLUTION
1. Get dimensions in common units.
2. Calculate volume in cubic centimeters.
3. Calculate the density.
0.95 mm •
1cm
10 mm
= 0.095 cm
57.54 g
6.4 cm3
= 9.0 g/ cm3
(9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm3
Note only 2 significant figures in the answer!
10. Percent Error
Measures how accurate the experimental data is.
(experimental value) − (true value)
% error = × 100
true value
11. Example:
• A metal block has a true value of 1.70 g/cm3.
A student measures the density of the block to
be 1.85 g/cm3. Calculate the percent error for
this measurement.
12. Example
• A student measured the density of water three
times and obtained the following results:
Trial 1: 0.996 g/mL
Trial 2: 1.03 g/mL
Trial 3: 0.964 g/mL
Water has a density of 1.00 g/mL.
A. Calculate the student’s percent error for each
trial.
B. Which trial had the greatest percent error?
13. PROBLEM: Mercury (Hg) has a density of
13.6 g/cm3. What is the mass of 95 mL of
Hg in grams? In pounds?
14. PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3.
What is the mass of 95 mL of Hg?
Strategy
1. Use density to calc. mass (g) from volume.
2. Convert mass (g) to mass (lb)
Need to know conversion factor
= 454 g / 1 lb
First, note that 1 cm3 = 1 mL
15. PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3.
What is the mass of 95 mL of Hg?
1. Convert volume to mass
95 cm3 •
13.6 g
cm3
= 1.3 x 103 g
1.3 x 103 g •
1 lb
454 g
= 2.8 lb
2. Convert mass (g) to mass (lb)
16. A solid displaces a matching volume of water
when the solid is placed in water.
33 mL
25 mL
Volume Displacement
17. What is the density (g/cm3) of 48 g of a metal if
the metal raises the level of water in a graduated
cylinder from 25 mL to 33 mL?
1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3
33 mL
25 mL
Learning Check
18. Which diagram represents the liquid layers
in the cylinder?
(K) Karo syrup (1.4 g/mL), (V) vegetable oil
(0.91 g/mL,) (W) water (1.0 g/mL)
1) 2) 3)
KW
W
V
VK
W
V
K
Learning Check
19. If blood has a density of 1.05 g/mL, how many
liters of blood are donated if 575 g of blood are
given?
1) 0.548 L
2) 1.25 L
3) 1.83 L
Learning Check
20. The density of octane, a component
of gasoline, is 0.702 g/mL. What is
the mass, in kg, of 875 mL of octane?
1) 0.614 kg
2) 614 kg
3) 1.25 kg
Learning Check
21. If blood has a density of 1.05 g/mL, how many
liters of blood are donated if 575 g of blood are
given?
1) 0.548 L
2) 1.25 L
3) 1.83 L
Learning Check
22. A group of students collected 125 empty
aluminum cans to take to the recycling center. If
21 cans make 1.0 pound of aluminum, how
many liters of aluminum (D=2.70 g/cm3) are
obtained from the cans?
1) 1.0 L 2) 2.0 L 3) 4.0 L
Learning Check
