1. Unit 2.2
Density

2. Question… What weighs more? 100 kg of feathers 100 kg of bowling balls
Or 100 kg of bricks?

3. Answer… They all weigh the same!
The mass is the same, they just have a different density.

4. Measuring Matter
Mass is a measurement of the quantity of matter in an object and the SI Unit is the gram (g).

5. Measuring Liquid and Solid Volume
Volume is a measurement of the how much space an object occupies, the SI Unit of liquid volume is the Liter (L)
1 Liter = 1 cubic decimeter(dm3)
1 mL = 1 cubic centimeter (cm3)

6. Density Density is the ratio the mass to the volume
Mathematically, density = mass/volume

7. M V D = Derived Units A derived unit is a combination of base units.
Density is a derived unit - mass per unit volume (g/cm3 or g/mL)
D = M V

8. Liquid Layers
Look at the picture of a variety of liquids. Which layer has the highest density?
Which layer has the lowest density?
Imagine that the liquids have the following densities:
10g/cm g/cm3.
6g/cm g/cm3.
Which number would go with which layer?

9. Density V = 825 cm3 M = DV D = 13.6 g/cm3 M = (13.6 g/cm3)(825cm3)
An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.
GIVEN:
V = 825 cm3
D = 13.6 g/cm3
M = ?
WORK:
M = DV
M = (13.6 g/cm3)(825cm3)
M = 11,220 g

10. Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL
1) A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?
GIVEN:
D = 0.87 g/mL
V = ?
M = 25 g
WORK:
V = M D
V = g
0.87 g/mL
V = 28.7 mL

11. Density M = 620 g D = M V = 753 cm3 D = ? D = 620 g 753 cm3
2) You have a sample with a mass of 620 g & a volume of 753 cm3. Find density.
GIVEN:
M = 620 g
V = 753 cm3
D = ?
WORK:
D = M V
D = g
753 cm3
D = 0.82 g/cm3