Transcript I. Units of Measurement - MR. Ahearn's Physical Science

Measurement
I. Units of Measurement
 Number vs. Quantity
 SI Base Units & Prefixes
 Derived Units
 Density Calculations
A. Number vs. Quantity
 Quantity - number + unit
UNITS MATTER!!
B. SI Units
Quantity
Base Unit
Symbol
meter
m
Mass
kilogram
kg
Time
second
s
Temp
kelvin
K
ampere
A
Length
Current
B. SI Units
Prefix
Symbol
Factor
megakilodecicentimillimicronanopico-
M
k
d
c
m

n
p
106
103
10-1
10-2
10-3
10-6
10-9
10-12
C. Derived Units
 Combination of base units.
 Volume - length  length  length
1 cm3 = 1 mL
1 dm3 = 1 L
 Density - mass per unit volume (g/cm3)
M
D=
V
M
D V
D. Density
 An object has a volume of 825 cm3 and a
density of 13.6 g/cm3. Find its mass.
GIVEN:
WORK:
V = 825 cm3
D = 13.6 g/cm3
M=?
M = DV
M
D V
M = (13.6 g/cm3)(825cm3)
M = 11,220 g
D. Density
1) A liquid has a density of 0.87 g/mL. What
volume is occupied by 25 g of the liquid?
GIVEN:
WORK:
D = 0.87 g/mL
V=?
M = 25 g
V=M
D
M
D V
V=
25 g
0.87 g/mL
V = 28.7 mL
D. Density
2) You have a sample with a mass of 620 g &
a volume of 753 cm3. Find density.
GIVEN:
WORK:
M = 620 g
V = 753 cm3
D=?
D=M
V
M
D V
D=
620 g
753 cm3
D = 0.82 g/cm3