Question

Identify R and R' in Equation 1 when the ester, aspirin, is made from salicylic acid and acetic acid. (Equation 1) Calculate the theoretical yield of aspirin to be obtained in this experiment, strating with 2.0g of salicylic acid and 5.0mL of acetic anhydride (density 1.08 g/mL).

Answer 1

In aspirin synthesis, R is salicylic acid and R' is the acetyl group from acetic anhydride. Theoretical yield calculation involves converting volumes to masses using density, calculating moles based on molecular weights, identifying the limiting reagent, and then converting moles of aspirin to grams for the yield.

Step-by-step explanation:

In the synthesis of aspirin from salicylic acid and acetic anhydride, R represents the salicylic acid and R' represents the acetyl group from acetic anhydride. The overall reaction can be represented as:

Salicylic acid (C7H6O3) + Acetic anhydride (C4H6O3) → Aspirin (C9H8O4) + Acetic acid (C2H4O2)

To calculate the theoretical yield of aspirin:

1. 
   
3. Convert the volume of acetic anhydride to mass using its density (5.0 mL × 1.08 g/mL = 5.4 g).
4. 
   
6. Using the molecular weights, calculate the moles of salicylic acid and acetic anhydride.
7. 
   
9. Determine the limiting reagent based on the stoichiometry of the reaction (1 mol C7H6O3 reacts with 1 mol C4H6O3).
10. 
    
12. Calculate the moles of aspirin expected based on the amount of limiting reagent.
13. 
    
15. Convert moles of aspirin to grams using its molecular weight to obtain the theoretical yield.

This experiment teaches us about esterification, the theoretical yield, and the importance of stoichiometry in chemical synthesis.

Answer 2

in theoretical yield are obtained 2.61 g of aspirin from 2.0 g of salicylic acid and 5 mL of acetic anhydride

Step-by-step explanation:

Aspirin (C9H8O4)

∴ mm C9H8O4 = 180 g/mol

salicylic acid (C7H6O3)

∴ mm C7H6O3 = 138 g/mol

acetic anhydride (C4H6O3)

∴ mm C4H6O3 = 102 g/mol

acetic acid (C2H4O2)

∴ mm C2H4O2 = 60 g/mol

reaction:

• C7H6O3 + C4H6O3 → C9H8O4 + C2H4O2

∴ g C7H6O3 = 2.0 g

∴ g C4H6O3 = (5.0 mL)(1.08 g/mL) = 5.4 g

limit reagent (L.R):

∴ n C7H6O3 = (2 g)(mol/138 g) = 0.0145 mol C7H6O3 (L.R)

∴ n C4H6O3 = (5.4 g)(mol/102 g) = 0.053 mol C4H6O3 (E.R)

theoretical yield:

Amount of product predicted by balanced equation when all limit reagent reacts

⇒ n C9H8O4 = (0.0145 mol C7H6O3)(mol C9H8O4/mol C7H6O3) = 0.0145 mol C9H8O4

⇒ g C9H8O4 = (0.0145 mol)(180 g/mol) = 2.61 g C9H8O4