FACTOR LABEL METHOD

 In math you use numbers, in chemistry we use quantities.  A quantity is described by a number and a unit.  100 is a number : 100 Kg is a quantity

Sometimes You Have to Convert Between Different Units  How many seconds are in a day?  How many inches are in a centimeter?  If you are going 50 miles per hour,how many meters per second are you traveling?  To answer these questions you need to change (convert) from one unit to another.

What is dimensional analysis?  The converting from one unit system to another.  If this is all that it is, why make such a fuss about it? Very simple. Wrong units lead to wrong answers. Scientists have thus evolved an entire system of unit conversion.

How does it work?  It will involve some easy math (Multiplication & Division)  To perform any conversion, you need a conversion factor.  Conversion factors are made from any two terms that describe the same or equivalent “amounts” of what we are interested in.  For example, we know that:  1 dozen = 12  12 inches= 1 foot  1 mile= 5280 ft  1 inch = 2.54 centimeters

 Look at the formula above you will use this solve the problem  60 inches=__________ ft  Step one what’s your Starting unit?  Inches  What’s your Desired unit?  Feet  What conversion factor are you going to use to convert inches to feet?  1 foot= 12 inches  Now plug it in!!  60 inches X 1 foot = 5ft 12 inches

Now Use the formula and Solve these  73 inches ___________cm  1779 sec ___________minutes

 This is a DIFFERENT FORMULA LOOK!!  3.5 miles = ________m Step 1 what’s the starting unit? Correct==miles What’s the Desired? feet What are the conversion factors you will use? Look at your conversion sheet? How can we get from miles to Meters? 1 mile= 5280ft AND 1 ft = m Now set it up …..remember Feet will be our linking unit because it’s linking our starting to desired

 3.5 miles = ________m  3.5 miles X _______feet X ________meters = meters  mile feet  Now fill it in with the conversion factors  3.5 miles X 5280feet X _0.3048meters = meters  1 mile 1 ft 1 mile= 5280ft AND 1 ft = m

 3 m= ______in

 6 gal= _____ fl oz  (1 gal = 4qts) (1 qt = 32 fl oz)  What is Qts going to be?  Correct Linking !! Now set it up like the top formula?

 7 hrs=_______seconds  our conversion factors are going to be  Hours to min then minutes to seconds  1 hr= 60 min AND 1 min =60 seconds  Set it up

PRACTICE  How many grams in 150 pounds given the conversion factors 1 pound = kg and 1 kg = 1000 grams

. How many basketballs can be carried by 5 buses?  · 1 bus = 12 cars · 3 cars = 1 truck · 1000 basketballs = 1 truck

30 oranges = ______pineapples  1 pear = 2 melons  2 pineapples= 3 melons  5 pears= 4 oranges