There are C-H sp bonds in dibenzilideneacetone (aldol product shown below) 13. F

Question

There are C-H sp bonds in dibenzilideneacetone (aldol product shown below) 13. For the aldol reaction done in class a student used 2.50 mL of acetone (M.M. 58.09 g/mol, d- 0.790g/mL) and 4.01 mL of benzaldehyde (M.M.-106.13 g/mol, d- 1.04g/mL)). You must show all calculations, include units and significant figures all along the way, and circle your final answer please. NO WORK -NO CREDIT. M.M. product- 234.31 g/mol (15 pt.) Calculate: Balanced reaction using formulas The starting moles of each reagent Which is the limiting reagent? Be sure and show calculation. What is the theoretical yield (based on the limiting reagent)? If the actual yield obtained was 3.672 g, what was the percent yield?

Explanation / Answer

The balanced chemical reaction is:

2C6H5CHO + CH3COCH3 ---> C17H14O

Starting moles of benzaldehyde = Mass/MM = (Density*Volume)/MM = (4.01*1.04)/106.13 = 0.039

Starting moles of acetone = Mass/MM = (Density*Volume)/MM = (2.5*0.79)/58.09 = 0.034

Since 1 mole acetone needs 2 moles of benzaldehyde for complete reaction, so benzaldehyde is present in lesser amount than required, and is hence the limiting reagent.

So, theoretical molar yield of product = Moles of benzaldehyde/2 = 0.039/2 = 0.0195

theoretical yield of product = Moles*MW = 0.0195*234.31 = 4.57 g

So, % yield = (Actual yield/Theoretical yield)*100 = (3.672/4.57)*100 = 80.35%

Hope this helps !

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