But our lecturer said we Write in past simple tense
This English question involves literary analysis, grammar, or writing skills. The detailed response below provides a well-structured answer with supporting evidence and clear explanations.
ScanSolve AI Answer
You're on a roll — Here is the revised chemistry lab report, written in the past simple tense as requested.
Chemistry Lab Report: Preparation of Aspirin (Acetyl Salicylic Acid)
Title: Preparation of Aspirin (Acetyl Salicylic Acid)
Objective:
The objective of this experiment was to synthesize acetylsalicylic acid (aspirin) from salicylic acid and acetic acid, to determine the melting point of the synthesized product, and to calculate the percentage yield of the reaction.
Introduction:
Aspirin, chemically known as acetylsalicylic acid, was a widely used medication for pain relief, fever reduction, and anti-inflammatory purposes. It was typically synthesized through an esterification reaction where the hydroxyl group of salicylic acid reacted with an acetylating agent. In this experiment, salicylic acid reacted with acetic acid in the presence of an acid catalyst to form acetylsalicylic acid and water.
Materials:
Salicylic acid (1.5 g)
Acetic acid (6 mL)
85% sulfuric acid or phosphoric acid (catalyst)
Distilled water (20 mL)
Conical flask
Water bath
Ice bath
Filter apparatus (e.g., Büchner funnel, filter paper)
Heating plate
Procedure:
1. 1.5 g of salicylic acid was placed into a clean conical flask.
2. 6 mL of acetic acid was added to the flask.
3. A few drops of 85% sulfuric acid or phosphoric acid were carefully added as a catalyst.
4. The mixture was heated in a water bath at 90°C for 3 minutes.
5. The flask was removed from the water bath and allowed to stand until it was still hot.
6. 20 mL of distilled water was added to the flask and it was allowed to stand until crystallization began.
7. The flask was cooled in an ice bath to maximize the yield of crystals.
8. The crude aspirin crystals were filtered using a suitable filtration method.
9. The crude product was recrystallized from hot water to purify it.
10. The purified aspirin crystals were dried.
11. The melting point of the recrystallized aspirin was determined.
12. The final purified product was weighed to calculate the percentage yield.
Reaction Equation:
The reaction between salicylic acid and acetic acid to form acetylsalicylic acid (aspirin) was an esterification reaction:
$$ \text{HOC}_6\text{H}_4\text{COOH} \text{ (Salicylic Acid)} + \text{CH}_3\text{COOH} \text{ (Acetic Acid)} \xrightarrow{\text{H}_2\text{SO}_4/\text{H}_3\text{PO}_4} \text{CH}_3\text{COOC}_6\text{H}_4\text{COOH} \text{ (Acetylsalicylic Acid)} + \text{H}_2\text{O} \text{ (Water)} $$
Data and Observations:
The mass of salicylic acid used was 1.5 g.
The volume of acetic acid used was 6 mL.
Initial observations (e.g., appearance of reactants): [Record observations in past tense]*
Observations during heating (e.g., dissolution, color changes): [Record observations in past tense]*
Observations during cooling and crystallization (e.g., crystal formation): [Record observations in past tense]*
The mass of crude aspirin obtained was: [Record value] g*
The mass of recrystallized aspirin obtained was: [Record value] g*
The melting point of recrystallized aspirin was: [Record value] °C*
Calculations:
1. Molar mass of salicylic acid ($\text{C}_7\text{H}_6\text{O}_3$):
The molar mass of salicylic acid was calculated as:
$$ (7 \times 12.01) + (6 \times 1.01) + (3 \times 16.00) = 138.13 \text{ g/mol} $$
2. Moles of salicylic acid:
The moles of salicylic acid were determined to be:
$$ \text{Moles} = \frac{1.5 \text{ g}}{138.13 \text{ g/mol}} = 0.01086 \text{ mol} $$
3. Molar mass of acetylsalicylic acid ($\text{C}_9\text{H}_8\text{O}_4$):
The molar mass of acetylsalicylic acid was calculated as:
$$ (9 \times 12.01) + (8 \times 1.01) + (4 \times 16.00) = 180.17 \text{ g/mol} $$
4. Theoretical yield of aspirin: (Based on 1:1 stoichiometry with salicylic acid as limiting reactant)
The theoretical yield of aspirin was determined to be:
$$ \text{Theoretical yield} = 0.01086 \text{ mol} \times 180.17 \text{ g/mol} = 1.956 \text{ g} $$
5. Percentage Yield:
The percentage yield was calculated using the formula:
$$ \text{Percentage Yield} = \frac{\text{Actual mass of recrystallized aspirin}}{\text{Theoretical yield}} \times 100\% $$
$$ \text{Percentage Yield} = \frac{\text{[Record actual mass]} \text{ g}}{1.956 \text{ g}} \times 100\% = \boxed{\text{[Calculate value]} \%} $$
Results:
The theoretical yield of aspirin from 1.5 g of salicylic acid was calculated to be 1.956 g.
The actual mass of purified aspirin obtained was [Record value] g.
The percentage yield of the synthesis was [Calculate value] %.
The melting point of the synthesized aspirin was determined to be [Record value] °C. (The literature melting point for pure aspirin is 135-136 °C).
Discussion and Conclusion:
The experiment successfully synthesized aspirin from salicylic acid and acetic acid. The calculated percentage yield reflected the efficiency of the reaction and purification steps. A melting point close to the literature value of 135-136 °C indicated a high purity of the synthesized product. Any discrepancies in the melting point or a lower-than-expected percentage yield could have been attributed to factors such as incomplete reaction, loss of product during filtration or transfer, or the presence of impurities.
What's next? Send 'em!