Chemistry Lab Notebook | Lab 8: Organic Compounds in the Lab
Printed Name: Signature: Date:
_______________________ ___________________________ _____________________________
___
Name: Date: Experiment #: 8 Title: Organic Compounds
________________ _________________
Purpose: To synthesize aspirin from salicylic acid and calculate theoretical and percent yield; to identify four unknown
organic compounds using Tollens test, sodium nitroprusside test, solubility, and density; to test the enzyme lactase on milk,
sucrose, and lactose using glucose test strips; and to separate a mixture of biochemical molecules by ion exchange
chromatography and explain the order of elution.
Procedure Data / Results / Calculations
Part 1: Synthesis of Aspirin (Acetylsalicylic Part 1: Aspirin Synthesis Data & Calculations
Acid) Mass of salicylic acid: 3.2021 g
1. Weigh out salicylic acid into a small flask. Mass of filter paper: 0.1864 g
Record the exact mass. Mass of filter paper + crystals: 3.8739 g
Experimental yield of aspirin: 3.8739 − 0.1864 =
2. Add 6 mL of acetic anhydride to the flask. 3.6875 g
Swirl to mix, rinsing any remaining salicylic acid Purity Test (FeCl₃):
from the weighing boat. Add 5 drops of Salicylic acid control: turned purple ✓ (phenol group
concentrated H₂SO₄ as catalyst. confirmed)
Aspirin product: faint purple — some unreacted salicylic
Reaction: C₇H₆O₃ + (CH₃CO)₂O → C₉H₈O₄ + acid remains; less purple than control, indicating partial
CH₃COOH but incomplete conversion.
(salicylic acid + acetic anhydride → aspirin + Theoretical Yield Calculation:
acetic acid) Molar mass of salicylic acid = 138 g/mol
Molar mass of aspirin = 180 g/mol
3. Heat the mixture in a near-boiling water bath Mole ratio = 1:1 (salicylic acid : aspirin)
for 15–20 minutes. Observe the solution turning
light golden-yellow.
mol salicylic acid = 3.2021 ÷ 138 = 0.02320 mol
4. Remove from heat. Scratch inside of flask to mol aspirin = 0.02320 mol (1:1 ratio)
create nucleation sites. Add 40 mL of cold water Theoretical yield = 0.02320 × 180 = 4.176 g ≈ 4.17 g
to precipitate crystals. Transfer to an ice-water
bath for 10–15 minutes. Percent Yield:
% yield = (3.6875 ÷ 4.17) × 100 = 88.4%
5. Weigh a piece of filter paper. Vacuum filter the
crystals. Rinse with ice-cold water. Air dry, then
reweigh filter paper + crystals.
6. Purity test: dissolve a small amount of product
and a small amount of salicylic acid (control)
separately in water. Add a few drops of FeCl₃ to
each. A purple color indicates phenol group
(salicylic acid impurity); no color = pure aspirin.
7. Calculate theoretical yield, experimental yield,
and percent yield.
Part 2: Identification of Unknown Organic Part 2: Unknown Compound Results & Identification
Compounds Unk Tollens Nitropru Solubilit Position Density Identity
Unknowns A, B, C, D are selected from: now Test sside y (g/mL)
benzaldehyde, 1-bromobutane, cyclohexanone, n
propionic acid, toluene. A Negative Positive Insoluble Floats 0.933 Cyclohex
(red) (top) anone
Test 1 — Tollens Test (positive = aldehyde): B Negative Negative Insoluble Floats 0.838 Toluene
Page 1 of 4
Printed Name: Signature: Date:
_______________________ ___________________________ _____________________________
___
Name: Date: Experiment #: 8 Title: Organic Compounds
________________ _________________
Purpose: To synthesize aspirin from salicylic acid and calculate theoretical and percent yield; to identify four unknown
organic compounds using Tollens test, sodium nitroprusside test, solubility, and density; to test the enzyme lactase on milk,
sucrose, and lactose using glucose test strips; and to separate a mixture of biochemical molecules by ion exchange
chromatography and explain the order of elution.
Procedure Data / Results / Calculations
Part 1: Synthesis of Aspirin (Acetylsalicylic Part 1: Aspirin Synthesis Data & Calculations
Acid) Mass of salicylic acid: 3.2021 g
1. Weigh out salicylic acid into a small flask. Mass of filter paper: 0.1864 g
Record the exact mass. Mass of filter paper + crystals: 3.8739 g
Experimental yield of aspirin: 3.8739 − 0.1864 =
2. Add 6 mL of acetic anhydride to the flask. 3.6875 g
Swirl to mix, rinsing any remaining salicylic acid Purity Test (FeCl₃):
from the weighing boat. Add 5 drops of Salicylic acid control: turned purple ✓ (phenol group
concentrated H₂SO₄ as catalyst. confirmed)
Aspirin product: faint purple — some unreacted salicylic
Reaction: C₇H₆O₃ + (CH₃CO)₂O → C₉H₈O₄ + acid remains; less purple than control, indicating partial
CH₃COOH but incomplete conversion.
(salicylic acid + acetic anhydride → aspirin + Theoretical Yield Calculation:
acetic acid) Molar mass of salicylic acid = 138 g/mol
Molar mass of aspirin = 180 g/mol
3. Heat the mixture in a near-boiling water bath Mole ratio = 1:1 (salicylic acid : aspirin)
for 15–20 minutes. Observe the solution turning
light golden-yellow.
mol salicylic acid = 3.2021 ÷ 138 = 0.02320 mol
4. Remove from heat. Scratch inside of flask to mol aspirin = 0.02320 mol (1:1 ratio)
create nucleation sites. Add 40 mL of cold water Theoretical yield = 0.02320 × 180 = 4.176 g ≈ 4.17 g
to precipitate crystals. Transfer to an ice-water
bath for 10–15 minutes. Percent Yield:
% yield = (3.6875 ÷ 4.17) × 100 = 88.4%
5. Weigh a piece of filter paper. Vacuum filter the
crystals. Rinse with ice-cold water. Air dry, then
reweigh filter paper + crystals.
6. Purity test: dissolve a small amount of product
and a small amount of salicylic acid (control)
separately in water. Add a few drops of FeCl₃ to
each. A purple color indicates phenol group
(salicylic acid impurity); no color = pure aspirin.
7. Calculate theoretical yield, experimental yield,
and percent yield.
Part 2: Identification of Unknown Organic Part 2: Unknown Compound Results & Identification
Compounds Unk Tollens Nitropru Solubilit Position Density Identity
Unknowns A, B, C, D are selected from: now Test sside y (g/mL)
benzaldehyde, 1-bromobutane, cyclohexanone, n
propionic acid, toluene. A Negative Positive Insoluble Floats 0.933 Cyclohex
(red) (top) anone
Test 1 — Tollens Test (positive = aldehyde): B Negative Negative Insoluble Floats 0.838 Toluene
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