chemistry equation

Question

Ethanol (C2H5OH) is produced from the fermentation of sucrose (C12H22O11) in the presence of enzymes.  

         C12H22O11 (aq) + H2O (g) 🡪 4 C2H5OH (l) + 4 CO2 (g)

   A scientist performed the reaction with 684 grams of sucrose and 225 grams of water and was able to produce 349 grams of ethanol. Determine the percent yield of this reaction.

Answer 1

C₁₂H₂₂O₁₁ (aq) + H₂O (g) ==> 4C₂H₅OH (l) + 4CO₂ (g)

684 g....................225 g..............?...........................

Using dimensional analysis and the stoichiometry of the balanced equation, we find mass of C₂H₅OH...

684 g C₁₂H₂₂O₁₁ x 1 mol C₁₂H₂₂O₁₁ /342 g x 4 mol C₂H₅OH/molC₁₂H₂₂O₁₁ x 46.1g/mol C₂H₅OH = 369 g

225 g H₂O x 1 mol H₂O/18 g x 4 mol C₂H₅OH/mol H₂O x 46.1 g/mol C₂H₅OH = 23o5 g C₂H₅OH

So, C₁₂H₂₂O₁₁ is limiting and the theoretical yield of C₂H₅OH = 369 g

% yield = actual yield/theoretical yield (x100%) = 349 g/369 g (x100%) = 94.6% yield