Question

What is the % yield of the reaction making 1.6 g of acetyl salicylic acid from 5.7 g of salicylic acid, 9.9 mL of acetic anhydride (density 1.082), and 10 drops 85 % weight phosphoric acid (density 1.685)? Use the molecular weights that you have already calculated. Give two significant figures.

Answer 1

Answer:

Yield of reaction is 76.7%

Explanation:

The reaction of salicylic acid with acetic anhydride to produce acetyl salicylic acid is 1:1. That means 1 mole of salicylic acid reacts with 1 mole of acetic anhydride (Acid is catalyst of reaction).

Moles of salicylic acid are:

$5.7g\frac{1mol}{138.121g} = 0.04127 moles$

And moles of acetic anhydride are:

$9.9mL\frac{1.082g}{mL} \frac{1mol}{102.09g} = 0.105 moles$

As salicylic acid is limiting reactant, theoretical moles of acetyl salicylic acid are 0.04127mol. That means theoretical mass of acetyl salicylic acid is:

$0.04127moles\frac{180.158g}{1mol} = 7.435g$

Thus, yield of reaction is:

$\frac{5.7g}{7.435} *100=$ 76.7%