Density

1
Density

• All substances have different densities,
  therefore, you can identify a substance if you
  know its density
• The formula to calculate somethings density is
• When we calculate density, the units we use are
  either g/mL or g/cm3. How do we know which set
  of units to use?

M
D
V
2

• g/ml - liquids
• volume of liquids are measured in milliliters
• g/cm3 for solids
• Volume of solids are measured in cm3

3
Mass

• To find mass, we put the object on a balance
• Mass is always in grams
• How do we find volume?

4
Volume - two options

• Liquids
• Use a graduated cylinder to find the volume in mL
• Solids
• If possible, measure length, width, and height
  then multiply to get your volume in cm3
• If not, use displacement of water to measure
  volume (you will need to convert to cm3 when you
  are done because it is a solid)

5
Measuring Solid Volume
We can measure the volume of regular object using
the formula length x width x height.
_____ X _____ X _____ _____
6
Calculate the volume
7
Water

• What is the density of water?
• Now you know how to find mass and volume, you can
  find the density of objects.

8
Practice 1

• V 15 mL
• M 45 g
• D ?
• D m/v 45 g/ 15mL
• D 3g/mL

9
Practice 2

• V 10 mL
• M 100 g
• D ?
• D m/v 100 g/10mL
• D 10 g/mL

10
Practice 3

• V 17 mL
• M 34 g
• D ?
• D M/V 34 g/ 17 ml
• D 2 g/mL

11
Practice 4

• M 45 g
• D 9 g/cm3
• V ?
• V m/d 45 g/ 9 g/ cm3
• V 5 cm3

12
Practice 5

• M 144 g
• D 12 g/cm3
• V ?
• V m/d 144 g/12 cm3
• V 12 cm3

13
Practice 6

• M 27 g
• D 108 g/cm3
• V ?
• v m/d 27 g/ 108 g/cm3
• V .25 cm3

14
Practice 7

• D 12 g/mL
• V 3 mL
• M ?
• M d x v 12 g/mL x 3 mL
• M 36 g

15
Practice 8

• D 1445 g/mL
• V 2 mL
• M ?
• M d x v 1445 g/mL x 2 mL
• M 2890 g

16
Practice 9

• D 3.54 g/mL
• V 22 mL
• M ?
• M d x v 3.54 g/mL x 22 mL
• M 77.88 g