Unit Conversion: The Factor Label Method

• You can convert from one unit to another using a conversion factor

• A conversion factor is an expression for the relationship between units– Ex: converting 90 minutes to hours

Step 1

• Show what you are given on the left and what units you want on the right

• 90 min = ? Hrs

Step 2

• Insert the required conversion factors to change between units

• Only one conversion factor is needed– The conversion factor is shown as the fraction

1hr/60min.– The minutes unit is placed on the bottom so it will

cancel out with the minutes unit on the top– 90min x 1hr = ? hrs

60 min

Step 3

• Cancel units and solve the math90 min x 1 =1.5 hrs

60 min

Example:

A student determines that the density of a certain material is 4.46 g/cm3. What would be the density if this material in g/L?• Solve this problem in your notebook

ANSWER:

• To solve this problem you have to know how many cm3 is in 1 L (liter). 1L= 1,000 cm3

• Step1: Show what you are given on left, and the units you want on the right

4.46g/cm3 = ? g/ L • Step 2: Insert the required conversion factors

to change between units & cancel units were you can

• 4.46g/cm3 x 1 L = 1,000 cm3

• Step 3 Cancel units were you can and solve the math

4.46g/L = 0.0046 g/L 1000