How to make anhydrous ethanol (100% alcohol)

TL;DR

Learn how to obtain pure ethanol at home by using either distillation or molecular sieves as drying agents.

Transcript

Water and ethanol form what is known as an azeotrope. This occurs when a mixture of liquids has a higher or lower boiling point, than each of the individual components. In the case of ethanol a mixture of ninety-five percent ethanol to water boils at a lower temperature than pure ethanol. So the concentration of ninety-five percent there's really n... Read More

Key Insights

• 😥 Ethanol and water form an azeotrope, which affects their boiling points.
• 😒 Distillation and the use of drying agents like molecular sieves are two methods to obtain 100% ethanol.
• 💦 Molecular sieves selectively absorb water, leaving ethanol untouched.
• ❓ The concentration of ethanol can be determined using a hydrometer.
• ❓ The sieves, once used, can be regenerated for reuse.
• 🫗 Sieves may contain dust particles that can be minimized by being gentle while pouring the ethanol.
• 🏪 Distillation can remove denaturing agents from store-bought ethanol.

Questions & Answers

Q: What is an azeotrope and how does it relate to ethanol and water?

An azeotrope is a mixture of liquids with a boiling point lower or higher than that of its individual components. In the case of ethanol and water, a mixture of 95% ethanol and water boils at a lower temperature than pure ethanol.

Q: Can distillation be used to obtain a higher concentration of ethanol than 95%?

No, distillation cannot further concentrate ethanol beyond 95%. However, other methods, such as adding another solvent that forms an azeotrope with water at a lower temperature, can be used to separate water from ethanol and obtain a higher concentration.

Q: What are molecular sieves and why are they used as drying agents?

Molecular sieves are substances with small pores that can selectively absorb water molecules, leaving larger molecules like ethanol untouched. They are used as drying agents because they effectively remove water from ethanol, resulting in a higher concentration of ethanol.

Q: What are some common uses for 100% ethanol?

100% ethanol is commonly used in various chemical reactions where the absence of water is required. It can also be added to gasoline, although this use may not apply to everyone.

Summary & Key Takeaways

• Water and ethanol form an azeotrope, a mixture with a boiling point lower than that of pure ethanol.

• Two methods to obtain 100% ethanol are through distillation or by using drying agents like molecular sieves.

• Molecular sieves, with their small pores, selectively absorb water and leave ethanol untouched, resulting in pure ethanol.