Dimensional Analysis Mrs. Stoops Chemistry

What is it? Process for changing the units without altering the amount. If you have 4 quarters, you also have 1 dollar or 10 dimes. All of these are the same values just represented differently.

Why do you need it? We measure in one unit and need to express it in another unit. We will need to change units for calculations in chemistry. Learn it now, this concept will keep coming back!!!!!

Conversion factors Conversion factors are EQUAL Expressed in one thing = another different thing 1 foot = 12 inches 1 mile = 5280 feet 1 hour = 60 minutes

Think about it! For your next birthday, I will give you 1 penny for every second you have lived if you can tell me how many dollars I would owe you. What facts would we need: –Year = 365 days –Day = 24 hours –Hours = 60 minutes –Minute = 60 seconds –1 dollar = 100 pennies

Set it up! Your age in whole years All starting values are over 1 Place factor so that first unit (years) cancels out What unit would go on the bottom of the next fraction?

Continue the problem Make sure all the units cancel out! Given in the problem

Solve it! Numbers on the top = multiply Numbers on bottom = divide Ignore ones __ x 365 x 24 x 60 x 60  100 =

How much do I owe you? 18 years = $5,676, years = $5,361, years = $5,045, years = $4,730,400 Will you accept a check? A bouncing one?

How fast ARE you going? So just how fast do you drive on the highway? 70 mph, 75 mph, 80 mph? Calculate the speed you do in feet per second.

What do you need to know? Starting speed = 75 mile per hour = 1 mile = 5280 feet 1 hour = 60 min 1min = 60 sec

Set it up, speedy! That’s like, three times the width of this room every second!

Fastest Sprinter Anyone run track, the 100 meter dash? How fast can you go? Tyson Gay ran the 100 meter dash in 9.68 sec. Factors needed: 1 in = 2.54 cm 100 cm = 1 m 5280 ft = 1 mile

How fast is that? Change 9.68 sec per 100 meters into fraction form: Change m/sec into mile per hour 23.1 mph

Add some dimension If this box is a square and has sides that measure 10 inches each and we need to ship it internationally and the rates are only given in cm 3 we would need to convert the measurement. First find the volume for the inches 10 in x 10 in x 10 in = 1000 in 3

Convert the in 3 to cm 3 We can convert 1 in to 2.54 cm. Just repeat the process for all 3 dimensions. BUT do the math in one step. Cube the number before doing the conversion cm 3 Same process for squares, just raise all factors to the exponent needed