1. Using the Conversion Factor
Objective: Make unit conversions

2. Unit conversion factor
A unit conversion factor is a fraction whose numerator and denominator are equivalent measures. Some common unit conversion factors are given below. You can also use the reciprocal of these.
Ask for some reciprocals so you know they understand.

3. Choose a unit conversion factor that…
Introduces the unit you want in the answer
Cancels out the original unit so that the one you want is all that is left.
IN ORDER FOR UNITS TO CANCEL, THEY MUST BE DIAGONAL

4. “Canceling” out Words

5. Practice: Choose the appropriate conversion factor.
Inches to feet
Minutes to hours
Meters to centimeters
inches needs to be on the bottom (DIAGONAL) to cancel
minutes needs to be on the bottom (DIAGONAL) to cancel
meters needs to be on the bottom (DIAGONAL) to cancel

6. Convert 8 yards to feet… = 24 ft
Make a decision: What conversion factor will you use?
Set up the problem: Multiply the measurement by the conversion factor.
Solve the problem: Perform the multiplication
= 24 ft

7. A bucket holds 16 quarts. How many gallons of water will fill the bucket? Use a unit conversion factor to convert the units.
What are the two conversion factors comparing quarts and gallons?
Which one will “cancel” quarts?
= 4 gal
16 qt 

8. One bag of apples weighs 64 ounces. How many pounds does it weigh?
= 4 lbs
Darren drank 2 liters of water. How many milliliters of water did he drink?
= 2000 mL

9. = 117 ft/s = 6.71 x 108 mph Convert 80 miles per hour to feet per sec.
= 117 ft/s
Convert 3 x 108 m/s to miles per hour.
= 6.71 x 108 mph

10. Convert 32 feet per min to inches per second.
= 6.4 in/s
A craft store charges $1.75 per foot for lace. How much per yard is this?
= $ 5.25 per yard

11. 2.196 x 1024 Ar atoms How many Argon atoms are in 8170 mL?
Recall : 1 mol = 6.02 x 1023 atoms
1 mol of argon occupies 22.4 L
How many Argon atoms are in 8170 mL?
2.196 x 1024 Ar atoms