Ch. 6 & 9 moles & stoichiometry                    test     [70 points]                   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.

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1.  Determine the empirical formula of a compound containing 40.0 % carbon, 6.7% hydrogen, and 53.3% oxygen.  [15 points]

2.  solve  [15 points]

a.  0.00150 mole sulfur dioxide = __ g sulfur dioxide

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

c.  0.0666 mole C3H8  =  __ C3H8 molecules

3.  Determine the empirical formula of the compound based on the following information:

1.0 g CxHyOz  +  excess O2  à  2.2 g CO2  +  1.2 g H2O.    [25 points]

4.  Benzene, C6H6, reacts with bromine, Br2, to form bromobenzene, C6H5Br.   [15 points]

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 ?