Question

calculate the theoretical yield and percentage yield of 0.053 g of benzil reacted with 0.09 g of NaBH4 (excess) in order to form 1R, 2S- meso hydrobenzoin the actual amount of product obtained is 0.406 g

Answer 1

Reaction is : OH OH IR, 25-meso Nabhu hydrobenzoin Mass = 0.0539 Molar mass= 214.26 g/mol Molar = 210.23 g/mol Mass obtained = 0.406 g Mass Moles mass 0.053 g Molar mass 210.239/mol = 2.52x10 mol Since Na BHy is in excess , benzil is the limiting reagent. I mol benzil gives I mal product. So 12:52 810-4 mol benzil will give 2052 810-4 mol product.

Mass = Moles x Molau Mass hydrobenzoin = 2052 X 10-4 mol X 214.26 g molt = 0. 054 g Theoretical yield = 0.054 g Percent yield' - Actu Mass obtained X100% 0.4069 X100% = 751.8 % 0.0549 = 0.406 a Theoretical masse