HINT: The density of a sample equals the ratio of its mass over its volume; Sometimes
the measure of grams may change while the volume remains the same for different
substances; however, density of differing materials will remain unchanged. Hence, we
can identify materials by the physical property of density.
1. What is the density of a piece of wood that has a mass of 25g and a
volume of 29.4 cm3 ?
2. A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has a
mass of 80.0 grams. What is the density of the wood?
3. A cup of gold colored metal beads was measured to have a
mass 425 grams. By water displacement, the volume of the
beads was calculated to be 48.0 mL3. Given the following
known densities, identify the metal.
Gold: 19.3 g/cm3
Copper: 8.86 g/ cm3
Bronze: 9.87 g/ cm3
RECALL… to find the density you must take steps.
Step 1—Find the mass in Grams.
Step 2—Find the volume. (measure and multiply l*w*h;
or, use water displacement for odd shapes)
Step 3 –Use your “heart”….
Mass
Divided by
Volume
= DENSITY
KEY
Density = Mass divided by Volume.
1)
mass of 25g
volume of 29.4 cm3
25
29.4 = 0.85 g/cm3
2)
Mass of 80.0 grams
80
72 = 1.1 g/cm3
Volume = 3.0 cm X 6.0 cm X 4.0 cm
=
3)
( 72 cm3)
Mass of 425 grams
425
48.0 = 8.85 g/mL3
Volume 0f 48.0 mL3
The metal must be Copper 8.86 cm3. To be certain, we would need test
additional physical properties such as luster, malleability, conductivity,
ductility, etc.
Remember to practice and continuously review previous material!
6th grade Science ROCKS!!
Ms. Higgins