Topic: Chem MathAim: How do you perform unit

conversions? What is the factor label method?

Do Now: How many inches in a foot? Feet in a yard? So… how many inches are in a

yard?HW:

Unit Conversions

• Units important in ALL CALCULATIONS• Factor Label Method - preferred way to show

conversions between quantities• You’ll have: given unit• Need to find: desired unit• Performed by cancelling units (moles, grams,

liters, molecules)• It’s pretty much awesome.

Unit Conversions – I show you.

• Convert 6 feet to inches• Easy – 72 inches• You did conversion based on the ratio of 1ft =

12in• Write given # & unit on left, desired unit on

right• Input conversion factor between

Unit Conversions

What you haveConversion factor

What you want

_12 in_1 ft

_6 ft_ _? inX =

_1 ft_12 in

_6 ft_ _? in=X

Unit Conversions

• When you set up your conversion factor, put the unit you want to GET RID OF on the BOTTOM, and the unit you WANT on the TOP.

desired___ get rid of

Unit Conversions• Convert 19 ft to yd• What do we know?• What do we want to know?• What conversion factor do we use?• Set up the conversion!• Which way does the conversion factor go? Why?• Calculate the answer!

Unit Conversions• Convert 13 yards to inches• What do we know?• What do we want to know?• What conversion factor do we use? (Hint: you

can use more than one!)• Set up the conversion!• Which way does the conversion factor(s) go?

Why?• Calculate the answer!

Unit Conversions

• Convert 4.8yd to mm• What do we know?• What do we want to know?• What conversion factor do we use? (Hint: you

can use more than one!) Also: 2.54cm = 1in• Set up the conversion!• Which way does the conversion factor(s) go?

Why?• Calculate the answer!

Unit Conversions

• The average life is 77 years.• Calculate the number of heartbeats in your

life. (avg 70 beats/minute)• Calculate the number of eye blinks in your life.

(avg 12 blinks/minute)