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:

Step-by-Step Solution

Answer

1 - (iii), 2 - (i), 3 - (ii), 4 - (iv).

Step 1: Identify Absolute Alcohol

Absolute alcohol, also known as pure or anhydrous alcohol, is ethanol with no water content. It is pure ethanol. Therefore, the correct match for absolute alcohol is (iii) anhydrous alcohol.

Step 2: Identify Denatured Alcohol

Denatured alcohol is ethanol that has been made undrinkable by adding toxic substances or chemicals, to discourage recreational consumption. The match for denatured alcohol is (i) alcohol made undrinkable by the addition of toxic materials or poisons.

Step 3: Understand 80% Proof Alcoholic Liquor

The proof system is a measure of alcohol content. In most countries, proof is twice the percentage of alcohol by volume. Therefore, an 80% proof alcoholic liquor contains 40% alcohol by volume. This matches with (ii) alcoholic liquor containing 40% ethanol by volume.

Step 4: Identify Rubbing Alcohol

Rubbing alcohol is commonly made from isopropyl alcohol, a different type of alcohol used for disinfection and cleaning. Therefore, rubbing alcohol corresponds to (iv) isopropyl alcohol.

Key Concepts

Absolute Alcohol

Absolute alcohol, often referred to as pure or anhydrous alcohol, is ethanol in its purest form without any water content. It is achieved by removing water from the alcohol through processes like distillation.

• Contains no water and is highly volatile.
• Used in laboratories and for industrial purposes due to its purity.
• It should be handled carefully as it is highly flammable and has strong intoxicating effects.

Ethanol, the main component, is commonly found in alcoholic beverages, but absolute alcohol is different due to its complete lack of water. The purity makes it unsuitable for drinking purposes but essential for certain scientific applications.

Denatured Alcohol

Denatured alcohol is ethanol made unsuitable for drinking by adding certain substances. These additives make the alcohol toxic, bad-tasting, or foul-smelling.

• Common additives include methanol, pyridine, and denatonium.
• Used as a solvent, fuel for spirit burners, and in cleaning products.
• Saves on taxes because it is non-consumable.

The primary reason for denaturing alcohol is to prevent its recreational consumption and avoid the beverage tax. Even though chemically similar to ethanol, the dangers associated with its additives require it to be used strictly for its intended industrial or domestic purpose.

Proof System

The proof system is a method of measuring the alcohol content within a beverage. This system varies by country, but in many places, proof is calculated as twice the percentage of alcohol by volume (ABV).

• An 80% proof liquor means it contains 40% alcohol by volume.
• Helps consumers understand the strength of their alcoholic beverages.
• Originated from historical methods to prove the presence of alcohol.

This system provides an understandable way of determining the potency of alcoholic drinks and making safe and informed drinking choices. Although it has features varying across different regions, the underlying concept remains the same.

Rubbing Alcohol

Rubbing alcohol is a type of alcohol mainly made from isopropyl alcohol instead of ethanol. It is specifically produced for topical use and not for consumption.

• Commonly used as a disinfectant to clean wounds or sanitize surfaces.
• Typically contains 70% isopropyl alcohol for effective germ-killing.
• Also used in various household applications like window cleaning and stain removal.

Rubbing alcohol has become a household staple due to its broad range of uses. Despite its name, it should never be consumed or used internally, as it can be dangerous if ingested.