Question

Why is ethyl alcohol not dried by anhydrous CaCl2?

Hint:

Use molecular sieves or anhydrous magnesium sulfate to dry alcohols like ethanol without any reaction.

Answer 1

Step 1: Understand the role of anhydrous CaCl2.
Anhydrous calcium chloride (CaCl2) is commonly used as a drying agent for liquids, as it absorbs water by forming hydrated calcium chloride.
Step 2: Why it doesn't dry ethyl alcohol.
However, ethyl alcohol (ethanol) contains a hydroxyl group (-OH) that can form hydrogen bonds with calcium chloride, causing it to react with the alcohol. This prevents anhydrous CaCl2 from effectively drying ethanol.
Step 3: Alternative drying agents.
To dry ethanol, substances like molecular sieves or anhydrous magnesium sulfate are more effective, as they do not react with the alcohol.
Final Answer: Anhydrous CaCl2 is not used to dry ethyl alcohol because it reacts with the alcohol, preventing it from absorbing water effectively.
Final Answer: \[ \boxed{\text{Anhydrous CaCl2 reacts with ethanol, forming hydrogen bonds and preventing it from drying effectively.}} \]