Calculate Theoretical Yield of Aspirin

Aspirin Synthesis Reaction:

\[ C_7H_6O_3 + C_4H_6O_3 \rightarrow C_9H_8O_4 + CH_3COOH \]

Salicylic Acid + Acetic Anhydride → Aspirin + Acetic Acid

Theoretical Yield of Aspirin:

1. Aspirin Synthesis Reaction

The synthesis of aspirin (acetylsalicylic acid) involves the reaction of salicylic acid with acetic anhydride in the presence of an acid catalyst (typically sulfuric acid). The balanced chemical equation is:

\[ C_7H_6O_3 + C_4H_6O_3 \rightarrow C_9H_8O_4 + CH_3COOH \]

This is an esterification reaction where the hydroxyl group of salicylic acid reacts with acetic anhydride to form aspirin and acetic acid as a byproduct.

2. How the Calculator Works

The calculator determines the theoretical yield based on stoichiometry:

Converts mass of salicylic acid to moles
Compares with moles of acetic anhydride
Identifies the limiting reagent
Calculates maximum possible aspirin yield

Key Formulas:

Moles of Salicylic Acid = Mass / 138.12 g/mol
Theoretical Yield = Limiting Moles × 180.16 g/mol

3. Understanding Theoretical Yield

Theoretical yield is the maximum amount of product possible if the reaction goes to 100% completion with no side reactions or losses. Actual yields in lab settings are typically lower (70-90%) due to practical factors.

4. Using the Calculator

Instructions:

Enter mass of salicylic acid in grams
Enter moles of acetic anhydride used
All values must be positive numbers
The calculator will identify the limiting reagent

5. Frequently Asked Questions (FAQ)

Q1: Why is acetic anhydride used instead of acetic acid?
A: Acetic anhydride is more reactive and produces better yields in this esterification reaction.

Q2: What's the typical yield in lab conditions?
A: Most student labs achieve 70-90% of theoretical yield due to practical losses and side reactions.

Q3: How can I improve my actual yield?
A: Use proper stoichiometry, complete drying, careful transfer of materials, and proper crystallization techniques.

Q4: What safety precautions are needed?
A: Use gloves and goggles - acetic anhydride is corrosive and salicylic acid is a skin irritant.

Q5: How do I calculate percent yield?
A: (Actual Yield / Theoretical Yield) × 100%. You'll need to measure your actual product mass.