ch. 6 & 9  moles & stoichiometry                   test   [60 points]          Chemistry

 

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

 

                                                                                                Signature:  ___________________

 

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer. 

 

1.  Solve   [20 points]

 

a.  5.0 g C2H6  =  __  moles C2H6

 

b.  5.0 millimoles water =  ___ g water

 

  c.  35.0 g nitrogen molecules  =  ___  nitrogen molecules

 

d.  1.25 * 1012 carbon dioxide molecules  =  __ moles of carbon dioxide

 

 

2.  Determine the empirical formula of a compound containing   [15 points]

 

              48.65 % carbon

                8.11 % hydrogen

              43.24 % oxygen

 

 

3.  Solve:  5.0 g C2H6  +  excess O2  à  __ g H2O  +  CO2       [10 points]

 

             

4.    What is the % yield in the below reaction:  [15 points]

 

3 Ca(NO3)2  +  2 Na3PO4  à  6 NaNO3  +  Ca3(PO4)2

                  10.0 g             10.0 g                                  5.0 g