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FACTOR LABEL METHOD. 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?
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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 ConvertBetween 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 = 0.3048 m Now set it up …..remember Feet will be our linking unit because it’s linking our starting to desired
1 mile= 5280ft AND 1 ft = 0.3048 m • 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 = 5632.7 meters • 1 mile 1 ft
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 = 0.454 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