Problem 156 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following: List I 1\. absolute alcohol 2\. denatured alcohol 3\. \(80 \%\) proof alcoholic liquor 4\. rubbing alcohol List II (i) alcohol made undrinkable by the addition of toxic materials or poisons. (ii) alcoholic liquor containing \(40 \%\) ethanol by volume (iii) anhydrous alcohol (iv) isopropyl alcohol The correct matching is: \(\begin{array}{llll}1 & 2 & 3 & 4\end{array}\) (a) (i) (iii) (ii) (iv) (b) (iii) (i) (ii) (iv) (c) (i) (iii) (iv) (ii) (d) (iii) (i) (ii) (iv)

Step-by-Step Solution

Answer

The correct matching is (d): 1-(iii), 2-(i), 3-(ii), 4-(iv).

Step 1: Understand Absolute Alcohol

Absolute alcohol is a form of alcohol that contains very little water, typically less than 1%. It is essentially pure alcohol. This matches with (iii) anhydrous alcohol.

Step 2: Understand Denatured Alcohol

Denatured alcohol is ethanol made unfit for drinking by the addition of toxic substances. This matches with (i) alcohol made undrinkable by the addition of toxic materials or poisons.

Step 3: Understand 80% Proof Alcoholic Liquor

Proof is a measure of alcohol content used in some countries. 80% proof means it contains 40% ethanol by volume. This matches with (ii) alcoholic liquor containing 40% ethanol by volume.

Step 4: Understand Rubbing Alcohol

Rubbing alcohol generally refers to isopropyl alcohol, which is used for its antiseptic properties. This matches with (iv) isopropyl alcohol.

Key Concepts

Understanding Absolute Alcohol

Absolute alcohol is another name for almost pure ethanol. It contains less than 1% water. Scientists often refer to it as "anhydrous alcohol." This means all the water content is removed.

• Purity: It is about 99% alcohol and 1% or less of water.
• Uses: It is utilized in scientific research, industrial processes, and pharmaceuticals.
• Manufacturing: Achieved by using drying agents to remove water or by distilling alcohol multiple times.

Absolute alcohol is vital for experiments where water could interfere with results. It's important to handle it safely due to its high concentration and potential flammability.

Denatured Alcohol: What Makes It Undrinkable?

Denatured alcohol is ethanol mixed with substances to make it poisonous for drinking, hence undrinkable. The primary purpose is to prevent human consumption while avoiding liquor taxes.

• Composition: Ethanol is combined with substances like methanol, bitrex, or other denaturing agents.
• Usage: This alcohol is widely used in cleaning products, fuel for homes, and industrial solvents.
• Safety: It can be harmful if inhaled or absorbed through the skin, so precautions are necessary when handling.

Understanding denatured alcohol ensures we use it correctly while maintaining safety standards.

The Concept of Proof Alcohol

"Proof alcohol" is often a confusing term. It indicates the strength of the alcohol beverage. The proof is calculated as twice the percentage of ethanol by volume. For example, an 80% proof beverage contains 40% alcohol.

• Measuring Alcohol Content: Divide the proof number by 2 to find the ethanol percentage.
• Example: 80% proof equals 40% total alcohol, and 100% proof equals 50% total alcohol.
• Use in different countries: The term "proof" can vary in meaning depending on the country, but most commonly follows the simple conversion rule.

By understanding proofs, we can make better-informed choices about alcoholic beverages.

Practical Uses of Rubbing Alcohol

Rubbing alcohol is a familiar household product, primarily consisting of isopropyl alcohol. It's predominantly used for its disinfectant properties.

• Composition: Typically containing 70% isopropyl alcohol and 30% water.
• Uses: Common applications include cleaning wounds, sanitizing surfaces, and even some DIY cleaning solutions.
• Safety Tips: Though effective, it's important to use rubbing alcohol in well-ventilated areas and keep it away from flames, as it is highly flammable.

Understanding how to use rubbing alcohol safely and effectively can help maintain good hygiene and prevent infections.