1. DENSITY Q) Which weighs more:-
A kilogram of feathers or a kilogram of iron?
DENSITY

2. Density is the Mass per unit Volume
What is Density?
If you take the same volume of different substances, then they will weigh different amounts.
Wood
Water
Iron
1 cm3
1 cm3
1 cm3
IRON
0.50 g
1.00 g
8.00 g
Q) Which has the greatest mass and therefore the most dense?
Density is the Mass per unit Volume

4. Cube Representations 1 m3 = 1 000 000 cm3
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 119

5. Density Equation: d = m V Mass Density = Volume Example:g
Mass
Density =
Volume
g/cm3
cm3
d = m V
Example:
Q) A gold-colored ring has a mass of 18.9 grams and a volume of 1.12 cm3. Is the ring pure gold? (The density of gold is 19.3 g/ cm3.)
d = m = 18.9g = g/cm3
V cm3
No – it is not pure gold!

6. DENSITY OF A REGULAR SOLID
Find the Mass of the solid on a balance.
Measure the three lengths and calculate the Volume.
(i.e., V = l x w x h )
Calculate the Density.
m = 240 g
2.0 cm
d = m = 240 =10.0 g/cm3 V
(2cm * 3cm * 4cm = 24 cm3)
3.0 cm
4.0 cm

7. DENSITY OF AN IRREGULAR SOLID
m = 360 g
d = m = 360 =12.0 g/cm3 V
Find the Mass of the solid on a balance.
Fill the Measuring Cylinder with Water to a known Volume.
Add the Object.
Work out the Volume of Water that is displaced.
Calculate the Density.
80 cm3
50 cm3

8. it floats What happens when you put an object in a fluid?
If the object is less dense than the fluid…
it floats

9. it sinks! What happens when you put an object in a fluid?
If the object is more dense than the fluid…
it sinks!

10. Neither floats nor sinks!
What happens when you put an object in a fluid?
If the object is as dense as the fluid…
Neither floats nor sinks!