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### Topic: Moles - How to solve for them using the factor label method  (Read 4459 times)

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#### AutumnIsabel

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##### Moles - How to solve for them using the factor label method
« on: October 29, 2006, 05:11:28 PM »
Okay, so i'm in a high school Lab Chemistry class... last class we got a worksheet with twenty mole problems... I have broken them down to four different types that confuse me... I'm going to write out the questions and show my work, I want to make sure i'm doing them right for my other problems. >.<

We have to use the factor label method with these... and significate figures.

1. 44g of NH4F is equal to _______ moles.
1 mole = 6.02 X 10 to the 23rd power
1 mole = 37g

44g         1 mole                                 1 mole                                      44
----  x   -------------------------------------  x ---------------------------------------------   = -------- = .0044 moles
1           37g                                         6.02x10 to the 23rd power      222.74

2. 4.8 x 10 to the 10th power molecules of NO2 is equal to ____ moles.
1 mole = 6.02 x 10 to the 10th power molecules or atoms
1 mole = 46g

4.8x10 to the 10th power molecules       1 mole                               1 mole        4.8
---------------------------------------------------  x ------------------------------------- x ------------- = ------------- = .017
1                                                      6.02x10 to the 23rd power    46g             276.92

Then I subtract the exponents and it ends up being .017 x 10 to the -13th power.

3.  387 moles of FeF3 is equal to ________g.
1 mole = 6.02 x 10 to the 23rd power
1 mole =  113g

387 moles      1 mole                                     113g        43,731
-------------- x  ------------------------------------------ x  ---------- = ------------- = 726 x 10 to the 23rd grams
1                 6.02 x 10 to the 23rd power   1 mole      6.02

4. 294,367 molecules of NaCl = ________g of NaCl.
1 mole = 6.02 x 10 to the 23rd
1 mole = 58

294,367 molecules         58g                                           17, 073,286
--------------------------- x ------------------------------------------------ =--------------------  = 283,609g x 10 to the 23rd
1                             6.02 x 10 to the 23rd molecules     6.02

I'm having trouble formating it properly. >.>