Name:  ______________________________                                                period:  _______

 

Ch. 6 & 9 moles & stoichiometry                    test     [90 points]                   honors Chem

 

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.                  Clearly identify the problems done and do them in sequence and your answer must begin and end on the same page of paper; otherwise, you will lose points.

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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:  ___________________

 

 

1.  Determine the empirical formula of a compound containing 40.0 % carbon, 6.7% hydrogen, and 53.3% oxygen.  [15 points; HW problem ch. 3ap; # 41c]

 

 

2.  1.0 g alcohol, which contains carbon, hydrogen, and oxygen, underwent complete combustion to form 2.2 g carbon dioxide and 1.2 g water.  Determine the empirical formula of the alcohol.  [25 points;  prior weekly quiz problem]

 

 

3.  solve  [15 points;  HW ch. 3ap; # 31 & 33]

 

a.  0.00150 mole sulfur dioxide = __ g

 

b.  1.05 * 1020 C8H10N4O2 (caffeine)  =  ___ g

 

c.  0.0666 mole C3H8  =  __ C3H8 molecules

 

 

4.  Solutions of sodium carbonate and silver nitrate react to form silver carbonate and sodium nitrate.  A solution containing 5.00 g of sodium carbonate is mixed with one containing 5.00 g of silver nitrate.  After the reaction is complete, the solutions are evaporated to dryness, leaving a mixture of salts.  How many grams of sodium carbonate, silver nitrate, silver carbonate, and sodium nitrate are present after the reaction is complete ? [20 points; HW problem ch. 3ap; # 71]

 

 

5.   A student reacts benzene, C6H6, with bromine, Br2, in an attempt to prepare bromobenzene, C6H5Br

 

            C6H6  +  Br2  à  C6H5Br  +  HBr

 

a.  what is the theoretical yield of bromobenzene in this reaction when 30.0 g of benzene reacts with 65.0 g of bromine ?

 

b.  if the actual yield of  bromobenzene was 56.7 g, what was the % yield ?   [15 points;  HW problem 74]