NECT Gr 12 Making Esters

Summary

In this chemistry lab video, John McBride and Joy Sparkles demonstrate the process of making esters through esterification, a reaction between alcohols and carboxylic acids. They emphasize safety precautions, especially when handling concentrated sulfuric acid, which acts as a catalyst. The video showcases the preparation of two esters: one from ethanoic acid and ethanol, and another from salicylic acid and methanol. The esters are separated from the reaction mixture using sodium carbonate, and their distinct smells are described, with one resembling enamel paint and the other, wintergreen.

Takeaways

• 🧪 Esterification is the reaction between an alcohol and a carboxylic acid to produce an ester and water.
• 🌸 Esters are known for their pleasant aromas and are used in the perfume and deodorizing industries.
• 🔬 Concentrated sulfuric acid acts as a catalyst in esterification reactions, speeding up the process without being consumed.
• ⚠️ Safety is paramount when handling concentrated sulfuric acid due to its corrosive and dehydrating nature.
• 🥼 Proper protective gear such as gloves and safety goggles is essential when conducting chemical reactions.
• 🌡 The reaction is often carried out in a water bath to control the temperature and prevent overheating.
• 💧 Sodium carbonate is used to separate the ester from the reaction mixture by neutralizing the acid.
• 🌬 The process involves careful addition of reagents and catalysts to avoid violent reactions.
• 🌡️ Heating the reaction mixture helps to speed up the reaction rate.
• 📝 It's important to let the reaction mixture cool before adding sodium carbonate to observe the ester formation.
• 📖 Students are encouraged to record observations and complete a worksheet as part of their school-based assessment.

Q & A

What are esters and what are they commonly used for?

Esters are fragrant substances that are volatile and have low boiling points. They are used in the perfume and deodorizing industry to manufacture artificial fragrances.

What is the esterification reaction?

Esterification is the reaction between an alcohol and a carboxylic acid that produces an ester and water.

What role does sulfuric acid play in the esterification reaction?

Sulfuric acid acts as a catalyst in the esterification reaction, speeding up the rate of reaction without being chemically changed during the process.

Why is safety important when handling concentrated sulfuric acid?

Concentrated sulfuric acid is a powerful dehydrating agent and is corrosive. It can cause severe chemical burns if it comes in contact with skin, so it must be handled with care.

What is the proper way to smell chemicals in a laboratory?

One should never smell chemicals by putting them under the nose and sniffing. Instead, the odor should be wafted towards the nose with the hand.

What are the reactants used in the first experiment described in the script?

In the first experiment, ethanoic acid and ethanol are used as reactants.

How is the reaction mixture heated in the experiment?

The reaction mixture is heated in a water bath, where a Bunsen burner is used to heat the water until it boils.

What is the purpose of adding sodium carbonate at the end of the reaction?

Sodium carbonate is added to separate the unreacted acid and the ester from the reaction mixture.

What is the difference between the reactions involving ethanoic acid and salicylic acid?

Ethanoic acid is a liquid, while salicylic acid is a crystalline solid. The method of adding the reactants and the catalyst differs slightly due to the solid state of salicylic acid.

What is the chemical formula of salicylic acid?

The chemical formula of salicylic acid is C7H6O3.

How is the reaction progress monitored in the experiment?

The reaction progress is monitored by observing changes in temperature, the formation of bubbles, and the appearance of an oily layer which indicates the formation of the ester.