A student prepared aspirin in a laboratory experiment using the following reaction.?

Question

C7H6O3 + C4H6O3 = C9H8O4 + HC2H3O2

salicylic acid acetic anhydride aspirin

The student reacted 1.75 g salicylic acid with 2.33 g acetic anhydride. The yield was 1.75 g aspirin. Calculate the theoretical yield for this experiment.

theoretical yield

Answer 1

Great Question

So you would need to find out the molecular mass of a couple of things:

Salicylic Acid = 138.123g/mol

Acetylsalicylic Acid (Asprin) = 180.160g/mol

The reaction is a 1:1 mole ratio

~~~~~~~~1 mol~~~~~~1 mol~~180.160 g

1.75 g x _______--x---_____-x--__________= 2.28g (theoretical)

~~~~~~~138.123g~~~~1 mol~~~1 mol~~~

Your theoretical yield is 2.28 g of Acetylsalicylic Acid (Asprin)

Answer 2

First, determine the number of moles of your reactants (i.e. salicylic acid and acetic anhydride)

given from the molecular formula:

MW salicylic = 138 g/mole

MW acetic anhydride = 102 g/mole

MW aspirin = 180 g/mole

moles of salicylic acid = 1.75 g / 138 g/mole = 0.0127 moles

moles of acetic anhydride = 2.33 g / 102 g/mole = 0.0228 moles

since the reaction is 1:1 ratio...then the number of moles of least value, which is the salicylic acid will be converted to aspirin...therefore

moles of salicylic acid = moles of aspirin (since the ratio is 1:1)

to determine the grams of aspirin:

g of aspirin = moles of aspirin x MW of aspirin

g of aspirin = 0.127 moles x 180 g/mole = 2.28 g is the theoretical yield