STUDENT TUTORIAL OF

 

PERCENT COMPOSITION PROBLEMS

 

EMPIRICAL FORMULAS

 

MOLECULAR FORMULAS

 

 

All three of these type problems progress from one to the next.  For example when you know how to do percent composition, you can then use that to do empirical formulas, and when you know how to do empirical formulas the next step is to convert them into actual molecular formulas.

 

 

  1. A.  Use this site to learn about how to calculate percent composition of a compound by using each element’s atomic weight in the compound with the compound’s molecular weight.  Click on continue until you get to page 6 and find out how to calculate the percent composition of  Na3PO4. (If this does not go directly copy and paste to your URL address.

          http://www.wisc-online.com/objects/index_tj.asp?objID=GCH7104

 

 

    1. Use this site for more written detail and practice with answers

http://www.ausetute.com.au/percentc.html

 

    1. Use this site for a fun interactive with percent composition.

http://chemistry2.csudh.edu/newlechelp/percentcompcs.html

 

 

  1.    A.  Now that you know how to calculate percent composition, learn how you can use this to calculate empirical formulas starting at the following site.

          http://chemwithtran.blogspot.com/2008/01/video-tutorial-empirical-formula.html

        If  your computer would not work with this site here is another good written site however this takes you on into molecular formulas, which you may not be ready for yet.

           http://www.nauticus.org/chemistry/chememperical.html

 

 

          B.  Practice your new found knowledge with this interactive question answer session.

                http://chemistry.csudh.edu/lechelpcs/empiricalformulascsn7.html

 

 3.      A.   Now that you know how to calculate empirical formulas from percent composition data complete what you have started by learning how you use empirical formulas to find the actual molecular formula

                      

                         http://www.chem.uiuc.edu/webFunChem/molform/MolForm.htm

 

                 B.  You will be better prepared for the molecular portion of the tutorial in this site now.

                                     http://www.nauticus.org/chemistry/chememperical.html

 

C.     Try  some of  these sample problems to see if you have the whole thing put together.  Do at least 1 of 1, 1of 2, B of 3, 1 of 4 , and 1 of 5.

 

        http://lhs2.lps.org/staff/sputnam/practice/UnitV_EmpForm.htm