Question

how do i calculate yield % and pure yield %??

I know i have to balance an equation first but C7H8O-> C7H6O does not make sense to me...

I believe benzyl alcohol is the limiting reagent

>N TEMPO O. CH2Cl2 KBr, NaOCI NaHCO3, H20 CyH2O Mol. Wt.: 108.14 I wo bp: 205°C V CyH60 Mol. Wt.: 106.12 bp: 178°C Crude data Student Data: Purified data (Silica Gel Column - see protocol for conditions) Pure mass: Not collected Pure yield: % Mass: 0.065 g colorless liquid yield: %

Answer 1

For these kinds of reactions, you do not need the total balanced equation. You need to fix your limiting reagent and the final major product. In this case, as shown in the above equation it is clear that the limiting reagent C7H8O and the final major product is C7H6O.

As 1 equivalent of the limiting reagent, C7H8O will give rise to 1 equivalent of the final major product, hence the expected yield will be 100%.

The molecular weight of Benzyl alcohol as provided is = 108.14, benzaldehyde is = 106.12. As provided Mol of the limiting reagent C7H8O is =
9.25 x 10-4
. Weight of the crude product = 0.065g. And the yield of crude product in mol is = (0.065/106.12) mol =
6.125 x 10-4
. The %yield is calculated using the following formula -

%yield = {(mol of the product obtained / mol of the limiting reagent) $\times$ 100}%

In this case %yield = {}% = 66.22 %.

(6.125 x 10-4/9.25 x 10-4) x 100

Similarly, if the pure mass is collected then the %pure yield can be calculated by using the same formula that in this case will be -

%pure yield = {(mol of the pure product obtained / mol of the limiting reagent) $\times$ 100}%