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

Yield of reaction is 76.7%

Step-by-step 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(1mol)/(138.121g) = 0.04127 moles`

And moles of acetic anhydride are:

`9.9mL(1.082g)/(mL) (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(180.158g)/(1mol) = 7.435g`

Thus, yield of reaction is:

`(5.7g)/(7.435) *100=` 76.7%