1. Ch. 2 - Measurement I. Units of Measurement (p.34-45)
Number vs. Quantity
SI Base Units & Prefixes
Derived Units
Density Calculations

2. A. Number vs. Quantity
Quantity - number + unit
UNITS MATTER!!

3. B. SI Units Base Unit Length- I meter m Mass- m gram g Time- t second
Quantity &
Symbol
Base Unit
Unit Symbol
Length- I
meter m
Mass- m
gram g
Time- t
second s
Temp- T
kelvin K
Current- I
ampere A

4. B. SI Units Prefix Factor mega- M 106 kilo- k 103 deci- d 10-1 centi-
Pre- Symbol
Factor
mega- M
106
kilo- k
103
deci- d
10-1
centi- c
10-2
milli- m
10-3
micro- 
10-6
nano- n
10-9
pico- p
10-12

5. D m V D= m V C. Derived Units Combination of base units.
Volume - length  length  length
1 cm3 = 1 mL dm3 = 1 L
Density - mass per unit volume (g/cm3) D m V D= m V

6. Problem Solving Steps
1 Givens:
2 Unknowns:
3 Equations:
4 Answer:

7. D m V D. Density V = 825 cm3 m = DV D = 13.6 g/cm3
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 D m V

8. Problem Solving Steps 1 Givens:
Include quantity, number, & unit symbols
2 Unknowns:
Include quantity & unit symbols
3 Equations:
Base equation & manipulated equation
4 Answer:
Do the units agree? Is it reasonable?

9. D m V D. 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 D m V
V = g
0.87 g/mL
V = 28.7 mL

10. D m V D. 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 m V
D = g
753 cm3
D = 0.82 g/cm3