1. Do Now: How many sig figs do the following numbers have? 53000 25.00
2000
5.60 x 1025

2. Density

3. Mass Mass is a measurement of the amount of matter
The SI unit - kilogram (kg)
Other common units include
Grams (g)
Milligrams (mg)
SI= Le Systeme International d’Unites
(international system of units)

4. Volume Volume is the amount of space occupied by an object
The derived SI unit is the cubic meter (m3)
Very inconvenient in lab
Usually use cubic centimeters (cm3) or..
Non-SI units liter (L) or milliliters (mL)

5. Density = Mass_ Volume

6. Thus, Density is measured in …
grams/milliliter
g/mL
g/cm3
g/cc
(cc = centimeters cubed)

7. Calculating Density-Identifying materials
density = mass
volume
d= m V m
(mass) d
(density) v
(volume)

8. Calculating Density-Identifying materials
What is the density of a sample that has a mass of 30. g and has a volume of 10. mL?

9. If you have 5. 0 g of vegetable oil (density= 0
If you have 5.0 g of vegetable oil (density= 0.93 g/mL) how much room is it occupying?

10. If you have 3.028g of a liquid occupying 4.2 mL of space:
what is the density? and
what liquid might you have?
What other physical properties might help you identify the liquid?

11. Densities of Materials
Category
Material
Density
(g/cc or g/mL)
Wood
Southern Pine
0.65
Chemical
Gasoline
0.721
Liquid
Ethyl Alcohol (drinking alcohol)
0.802
Other
Ice
0.897
Water & Ice
plastic
PP (polypropylene
Vegetable Oil
0.93
Water, 100 °C
0.9581
Water, 4 °C

12. Density is a little tricky…
The object with the most mass or most volume is not necessarily the most dense:
Can you think of any other examples like this?
Mass
Volume
Density
Aircraft Carrier
Heavy
Large
Less than Water
Wedding Ring
Light
Small
More than Water

13. Density
Density tells you how much matter is squeezed into each 1 cm3 of the material.
It does not depend directly on the volume or mass of the object.

14. Density Every pure material has a unique density.
Density is a physical property that allows you to identify materials.

15. Significant figures in calculations

16. Adding/Subtracting Sig Figs
Line up the decimal places
Draw a straight line just past the last digit they have in common.
Add/subtract
Keep everything to the left of the line.

17. 23.2
6.052
23.2
6.052
168.7
153
600
+ 168
921
900
0.0097
0.0660

18. Multiplying & Dividing Sig Figs
Round the answer to the same number of sig figs as in the number with the fewest sig figs.
23.2 x =
2.92
14.89 ÷ =
5000

19. 42.7 X =
0.20
407.1 / 12.3 =
33.1
2.7 X = 0.378
0.38

20. Exact Numbers Found by:
Counting (ex: I see 24 students in my class)
By definition (there are 12 inches in a foot or 1000 m in 1 km)
Do not take in account any exact numbers when counting sig figs during calculations.
*so if you are dividing #cm/#pages, the #pages is exact so your final answer will have the same number of sig figs as your # cm.