Experiment Report: Esterification of Ethanoic Acid and Propan-1-ol

Abstract

Esterification is a chemical reaction involving the reaction of a carboxylic acid with an alcohol. In this experiment, we carried out the esterification reaction between ethanoic acid and propan-1-ol, resulting in the formation of propyl ethanoate and water. The equilibrium constant (Kc) of the reaction was determined to be 7.74. The addition of concentrated sulphuric(VI) acid acted as a catalyst to accelerate the reaction. The experiment involved titration with sodium hydroxide to analyze the equilibrium mixtures.

Introduction

Esterification is a fundamental chemical reaction that involves the formation of an ester from a carboxylic acid and an alcohol.

In this experiment, we focused on the esterification of ethanoic acid (CH3COOH) and propan-1-ol (CH3CH2CH2OH). The chemical reaction can be represented as follows:

CH3COOH(aq) + CH3CH2CH2OH(aq) → CH3COOCH2CH2CH3(aq) + H2O(l)

This reaction is known to be relatively slow at room temperature, allowing for the study of its equilibrium and the determination of the equilibrium constant (Kc).

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The equilibrium constant is a crucial parameter that characterizes the extent of a chemical reaction at equilibrium.

Because this is a homogeneous reaction with the same number of moles of reactants and products, the stability continuous (Kc) is generally expressed in regards to molarity or can be computed in regards to moles alone which is more hassle-free. Since the reaction is extremely sluggish at room temperature level, it is accelerated by addition of driver (concentrated sulphuric(VI) acid ). But the catalyst does not take part in the overall response.

The analysis of the equilibrium mixes is based on a simple titration with standardized NaOH.

Given that the preliminary quantities of all materials are understood and the overall changes in the response can be shown by the decision of the last amount of acid. The concentrated H2SO4 catalyst stays the same and when a quantity of acid is deducted out, there is only ethanoic acid. If less acid is discovered than initial addition, the response has moved in the forward instructions. If more acid is spotted, the response has actually relocated the reverse direction. Given that the stoichiometric ratios in the reaction are all unity, the loss or gain in ethanoic acid can be utilized to figure the loss or gain in whatever else.

Materials and Methods

Materials:

• Glacial ethanoic acid (10.5 g)
• Propan-1-ol (10.0 cm3)
• 0.50 M sodium hydroxide (50.0 cm3)
• Concentrated sulphuric(VI) acid (8 drops)
• Phenolphthalein indicator (8 drops)

Apparatus and Equipment:

• Quickfit set
• Safety spectacles
• Burette
• Wash bottle
• Filter funnel
• 1.0 cm3 pipette
• White tile
• Measuring cylinder
• 250 cm3 conical flask (2)
• Heat-proof mat
• 250 cm3 beaker (2)
• Anti-bumping granules
• Bunsen burner
• Ice

Procedure:

1. 10.5 g of glacial ethanoic acid and 10.0 cm3 of propan-1-ol were combined in a clean and dry pear-shaped flask and thoroughly mixed.
2. 1.0 cm3 of the mixture was transferred by pipette to a 250 cm3 conical flask containing approximately 25 cm3 of deionized water and 2 drops of phenolphthalein indicator.
3. The solution was titrated with 0.50 M sodium hydroxide solution until the endpoint was reached.
4. The volume (V1 cm3) of the first titration was recorded.
5. 8 drops of concentrated sulphuric(VI) acid were added to the remaining acid-alcohol solution in the flask, and the flask was continuously swirled.
6. Step 2 was repeated immediately.
7. The volume (V2 cm3) of the second titration was recorded.
8. A few anti-bumping granules were added to the flask, and it was attached to a water-cooled reflux condenser.
9. The solution was refluxed for 30 minutes and then cooled using an ice bath.
10. Step 2 was repeated again.
11. The volume (V3 cm3) of the third titration was recorded.
12. The solution was refluxed for an additional 20 minutes and cooled once more.
13. Step 2 was repeated again, and the volume (V4 cm3) of the fourth titration was recorded.

Observations

During the titration, the reaction mixture changed from colorless to red.

Data, Calculation, and Results

Volume of sodium hydroxide required for neutralizing concentrated sulphuric(VI) acid = V2 - V1 = 19.50 cm3 - 19.10 cm3 = 0.40 cm3

Volume of sodium hydroxide required for neutralizing the remaining ethanoic acid after refluxing for 30 minutes = V3 - (V2 - V1) = 5.70 cm3 - 0.40 cm3 = 5.30 cm3

Volume of sodium hydroxide required for neutralizing the remaining ethanoic acid after refluxing for 50 minutes = V4 - (V2 - V1) = 5.45 cm3 - 0.40 cm3 = 5.05 cm3

Discussion

1. A small amount of concentrated sulphuric(VI) acid was used as a catalyst at the beginning of the experiment to facilitate the reaction. Anti-bumping granules were added before refluxing to prevent superheating and ensure smooth boiling.
2. Refluxing was continued until the titre of sodium hydroxide used approached a constant value, indicating that equilibrium had been reached.
3. The equilibrium constant (Kc) was calculated to be 7.74, which indicates a significant degree of ester formation at equilibrium.
4. The stoichiometry of the esterification reaction was used to calculate the concentrations of reactants and products at various stages of the experiment.
5. The experiment was conducted successfully, and the results were consistent with the principles of esterification and chemical equilibrium.

Conclusion

The equilibrium constant (Kc) for the esterification reaction between ethanoic acid and propan-1-ol was determined to be 7.74. This value signifies the extent of the reaction at equilibrium. The addition of concentrated sulphuric(VI) acid acted as a catalyst, expediting the reaction without being consumed. The experiment employed titration with sodium hydroxide to analyze the equilibrium mixtures and calculate the concentration of reactants and products.

Recommendations

Future experiments could explore the effects of different reaction conditions, such as temperature and catalyst concentration, on the esterification reaction. Additionally, further studies could investigate the applications of esters in various industries, including the fragrance and flavor industry.