i need help with my lab calculations? i am not sure how to calculate the theorit

Question

i need help with my lab calculations? i am not sure how to calculate the theoritical yield,percent yield, and Melting ranges of crude and pure.

Data:

    Mass     

         Melting point

Vanillian used

0.3858g

NaBH4 used

0.0734g

Crude product

0.9747g

75 °C

Pure product (vanillyl alcohol)

0.1748 g

91 °C

Calculation:

Vanillin M.W=152.2g/mol       NaBH4 M.W=37.83               Vanillyl alcohol M.W=154.2

Theoretical yield:

Percent yield:

Melting ranges of crude and pure:

    Mass     

         Melting point

Vanillian used

0.3858g

NaBH4 used

0.0734g

Crude product

0.9747g

75 °C

Pure product (vanillyl alcohol)

0.1748 g

91 °C

Explanation / Answer

Solution :-

Vanillin + NaBH4 ------ > Vanillyl alcohol

Theoretical mass of the product is calculated from the mass of vanilian

Mass of vanilian used = 0.3858 g

Mass of product formed = 0.1748 g

Theoretical yield = (0.3858 g vanilian * 154.2 g vanillyl alcohol / 152.2 g vanilian ) = 0.3909 g vanillyl alcohol

So the theoretical yield = 0.3909 g

Now lets calculate the percent yield

% yield = (actual yield / theoretical yield )*100%

             = (0.1748 g /0.3909 g)*100%

             = 44.72 %

Melting point range of vanillin = 81 to 83 C

Melting point range of vanillyl alcohol = 113 C

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