Measuring
and
Units
Measurement
The Dominion Mandate
requires us to gain
knowledge about God’s
creation.
To do so, we must
take measurements.
measurement
the act of comparing an
unknown quantity to a
standard unit
Types of Measurements
Quantitative
Uses numbers
Qualitative
Uses descriptions
Measurements
27 millimeters
Quantity Prefix Basic Unit
When you write a
measurement …
You must have a number.
You must have a unit.
(How much information does
the statement “I ran 7” give
you?)
instrument
a device to aid in measuring
Instrument
Has units on a scale
Is calibrated
Is accurately subdivided
Quantitative or Qualitative
4 feet
Extra large
Hot
100 degrees F
Sunny
96
SI System
(International System of
Units)
Started with the metric
system.
Expanded to SI.
SI System
(International System of
Units)
There are 7 base units.
We will use 5 of these.
base units
units that do not come from
other units
Chemistry Base Units
Length ………… Meter (m)
Mass …………… Kilogram (kg)
Amount ……….. Mole (mol)
Time …………… Second (s)
Temperature …. Kelvin (K)
derivative units
units derived from base units
Example:
Volume derives from length.
1 cubic decimeter = 1 liter
SI System
There are 22 derived SI units.
Example:
kg . m2
1J=1
s2
conversions
changing the units
Conversions
FACT:
As the unit size gets
larger, the number of
those units needed
becomes less.
milli
100,000 mg
centi
10,000 cg
deci
1,000 dg
-----
100 g
deka
10 dag
hecto
1 hg
kilo
0.1 kg
Conversions
Change 123,456.7 cm to km.
larger units
kilo, hecto, deka, ---, deci, centi, milli
smaller numbers
Centi to kilo moves 5 units to
the left.
Conversions
Change 123,456.7 cm to km.
We must move the decimal 5
spaces to the left.
123,456.7 cm becomes
1.234567 km.
Question
Convert 124 km to meters.
1. 1240 meters
2. 12,400 meters
3. 124,000 meters
4. 1,240,000 meters
mega
kilo
deci
centi
milli
micro
nano
unit conversion
The Chemist’s Secret Weapon
a tool used to solve
problems in which
units change
Unit Conversion
Example:
Change grams to tons.
Example:
Change feet/sec to miles/hr.
When you multiply or divide
numbers, do the same to their
units also.
Therefore, if the same unit is on
the numerator and denominator,
it “cancels out.”
This is how we change units.
conversion factor
a statement that two
quantities are equal
Grid Method
Given
Information
1
Conversion
Conversion
Factor
Factor
(if needed)
Conversion Factor
Example:
1 dozen eggs = 12 eggs
Usually written as a fraction
One dozen eggs
12 eggs
Unit Conversion
Change 1234 mm to meters.
1234 mm 1 cm 1 dm 1 m
10 mm 10 cm 10 dm
= 1.234 m
Unit Conversion
Convert 3625 cg to g.
3625 cg
1g
= 36.25 g
100 cg
Unit Conversion
How many pounds does a
37.6 kg boy weigh if 28.35 g
is equal to one ounce?
(1 lb is 16 ounces.)
Unit Conversion
37.6 kg to lbs
37.6 kg 1000 g 1 oz 1 lb
1 kg 28.35 g 16 oz
= 82.892416 lbs
= 82.9 lbs
Unit Conversion
How many grams are in a beef
patty that is 0.33 pounds?
(1 oz is 28.35 grams.)
0.33lb 16 oz 28.35 g
= 149.68 g
1 lb 1 oz
= 150 g
Unit Conversion
Calculate the cost of gas on a
round trip from San Francisco
to Los Angeles. The car used
gets 24 miles per gallon of
gasoline. Gas is $3.09 per
gallon. The distance between
the cities is 403 miles (one
way).
Unit Conversion
806 miles
1 gal $3.09
24 miles 1 gal
= $103.7725
= $104
Question
Convert 101 lbs to grams.
1.
2.
3.
4.
5.
34,905 g
0.21982 g
56.436 g
177.05 g
45,813 g