Consider the Fischer ester synthesis of methyl benzoate from benzoic acid and methanol in the presence of sulfuric acid as a catalyst. A reaction was performed in which 3.6 g of benzoic acid was reacted with excess methanol to make 1.4 g of methyl benzoate. Calculate the theoretical yield and percent yield for this reaction.

Respuesta :

Answer: The percent yield of the reaction is 32.04 %.

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]     .....(1)

Given mass of benzoic acid = 3.6 g

Molar mass of benzoic acid = 112.12 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of benzoic acid}=\frac{3.6g}{112.12g/mol}=0.0321mol[/tex]

The chemical equation for the formation of methyl benzoate from benzoic acid follows:

[tex]\text{Benzoic acid + Methanol}\rightarrow \text{Methyl benozate}[/tex]

By Stoichiometry of the reaction:

1 mole of benzoic acid produces 1 mole of methyl benzoate

So, 0.0321 moles of benzoic acid will produce = [tex]\frac{1}{1}\times 0.0321=0.0321mol[/tex] of methyl benzoate

Now, calculating the mass of methyl benzoate from equation 1, we get:

Molar mass of methyl benzoate = 136.15 g/mol

Moles of methyl benzoate = 0.0321 moles

Putting values in equation 1, we get:

[tex]0.0321mol=\frac{\text{Mass of methyl benzoate}}{136.15g/mol}\\\\\text{Mass of methyl benzoate}=(0.0321mol\times 136.15g/mol)=4.37g[/tex]

To calculate the percentage yield of methyl benzoate, we use the equation:

[tex]\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100[/tex]

Experimental yield of methyl benzoate = 1.4 g

Theoretical yield of methyl benzoate = 4.37 g

Putting values in above equation, we get:

[tex]\%\text{ yield of methyl benzoate}=\frac{1.4g}{4.37g}\times 100\\\\\% \text{yield of methyl benzoate}=32.04\%[/tex]

Hence, the percent yield of the reaction is 32.04 %.