1. Aim: How to use Dimensional Analysis to Convert from One unit to Another
DO Now: Answer the following questions in your notebook in the following format “60 seconds = 1 minute”
How many seconds are in minute?
How many minutes are in an hour?
How many hours are in a day?
How many days are in a week?
How many weeks are in a year?

2. Common units used in Chemistry

3. What is a Unit Conversion?
A unit conversion is a changing of one unit to another using a conversion factor.

4. What is a conversion factor
A conversion factor is an equality used to change one set of units to another
Examples of conversion factors
60 sec = 1 min
1000 m = 1 km
2.2 lbs = 1 kg

5. Unit Conversion 1 Foot = 12 inches 1 𝑓𝑜𝑜𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 = 1
A conversion factor can be written as two different fractions
1 Foot = 12 inches
1 𝑓𝑜𝑜𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 = 1
12 𝑖𝑛𝑐ℎ𝑒𝑠 1 𝑓𝑜𝑜𝑡 = 1

6. Using dimensional analysis
Given value x conversion factor Given value x 𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑢𝑛𝑖𝑡 𝑔𝑖𝑣𝑒𝑛 𝑢𝑛𝑖𝑡

7. Unit Conversion “ conversion factors” How many inches are in 3 ft.?
1 𝑓𝑜𝑜𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 = 𝑖𝑛𝑐ℎ𝑒𝑠 1 𝑓𝑜𝑜𝑡 = 1
“ conversion factors”
How many inches are in 3 ft.?
( 3 feet ) ( 12 𝑖𝑛𝑐ℎ𝑒𝑠 1 𝑓𝑜𝑜𝑡 ) = 36 inches
Conversion Factor

8. ( ) ______ How many cm are in 1.32 meters? equality: 1 m = 100 cm
applicable conversion factors:
______
1 m
100 cm
______
1 m
100 cm or ( )
______
1 m
100 cm
132 cm
X cm = 1.32 m =
We use the idea of unit cancellation
to decide upon which one of the two
conversion factors we choose.

9. Again, the units must cancel.
How many meters is 8.72 cm?
equality:
1 m = 100 cm
applicable conversion factors:
______
1 m
100 cm
______
1 m
100 cm or ( )
______
1 m
100 cm m
X m = 8.72 cm =
Again, the units must cancel.

10. Again, the units must cancel.
How many feet is inches?
equality:
1 ft = 12 in
applicable conversion factors:
______
1 ft
12 in
______
1 ft
12 in or ( )
____
1 ft
12 in
3.28 ft
X ft = in =
Again, the units must cancel.

11. Exit Slip
On a separate sheet of paper explain how conversion factors are used to convert between units.