Problem 107 - A Complete Resource Book in Chemistry for JEE Main

Question

1\. Match the following: List I List II \(\begin{array}{ll}\text { (dyes) } & \text { (Types of dyes) }\end{array}\) 1\. Orange I (i) Mordant dye 2\. Aniline yellow (ii) Acid dye 3\. Martius yellow (iii) Fibre reactive dyes (and congo red) 4\. Alizarin (iv) Basic dye (v) Direct dye The correct matching is: 1 \(2 \quad 3\) 4 (a) (iv) (iii) (i) (v) (b) (iv) (ii) (v) (i) (c) (ii) (iv) (v) (i) (d) (iii) (iv) (v) (i)

Step-by-Step Solution

Answer

The correct matching is (c) (ii), (iv), (v), (i).

Step 1: Understand the Dye Types

First, understand each type of dye and its characteristics: 1. Mordant dyes are dyes that require a mordant to fix onto the textile fibers. 2. Acid dyes are water-soluble anionic dyes applied to fibers with an acidic bath. 3. Fiber reactive dyes form covalent bonds with the fiber in the presence of an alkaline dye bath. 4. Basic dyes are cationic dyes that are applied in the presence of an alkaline environment. 5. Direct dyes are water-soluble dyes that adhere directly to the fiber without any need of a mordant.

Step 2: Match Orange I

Orange I is a type of dye typically categorized under acid dyes. Thus, the correct match for Orange I from List II is (ii) Acid dye.

Step 3: Match Aniline Yellow

Aniline yellow is known to be part of the basic dye category, which uses cationic properties. Therefore, Aniline Yellow matches with (iv) Basic dye.

Step 4: Match Martius Yellow

Martius yellow is a direct dye, meaning it can adhere directly to the fiber without a mordant. Therefore, it should be matched with (v) Direct dye.

Step 5: Match Alizarin

Alizarin is recognized as a mordant dye. It requires a mordant to bind properly with fibers, thus matches with (i) Mordant dye.

Step 6: Verify the Correct Matching

Now that the matches for all dyes are determined: 1. Orange I – (ii) 2. Aniline Yellow – (iv) 3. Martius Yellow – (v) 4. Alizarin – (i) These correspond to option (c) given in the exercise choices.

Key Concepts

Mordant Dye

Mordant dyes are unique because they require a particular substance known as a "mordant" to fix the dye onto the fabric. A mordant is a chemical that combines with the dye and the fiber, forming an insoluble compound, ensuring that the color adheres well and becomes wash-fast.
Mordants can be metallic salts like aluminum, iron, or chromium, and they act as a bridge between the dye and the fiber. This type of dye is typically used for natural fibers such as wool, cotton, and silk. The process results in vibrant and often long-lasting colors.

• Mordant dyes include colors such as Alizarin, which is used for dyeing wool and cotton fibres.
• They enable the creation of a variety of shades depending on the metal salt used as the mordant.

In practical applications, mordant dyes offer the versatility of producing different hues and shades from the same dye by altering the mordant, making them essential for artisans and textile artists.

Acid Dye

Acid dyes are prominently used for dyeing protein fibers like wool, silk, and some nylons. They are water-soluble and require an acidic environment to adhere to the fibers. During the dyeing process, the fibers are immersed in a dye bath containing acid (often acetic or sulfuric acid).
The acidic condition helps the dye to bind strongly to the fibers, leading to bright and vivid colors that are reasonably colorfast. These dyes work by forming ionic bonds with the fibers, which helps lock in the color.

• Popular acid dyes include Orange I, which is often used for dyeing delicate fibers.
• The process is mild, making it suitable for specialty fibers sensitive to harsh chemicals.

These characteristics make acid dyes especially popular in the textile industry where the longevity and intensity of color are critical.

Basic Dye

Basic dyes are known for their cationic properties, meaning they carry a positive charge. They are primarily used on fabrics that have negative charge sites or require vibrant colors. Basic dyes are most effective on acrylic fibers and also used on paper and leather because they are extremely bright and intense.
These dyes require an alkaline setting to work effectively, providing significant depth of color due to their strong ability to bond with materials that offer anionic sites.

• Aniline Yellow is an example of a basic dye, known for its vivid yellow hue.
• They are less used on cotton fabrics because of their potential to fade when washed.

In industrial settings, they are valuable for their superior bright hues and ease of use, particularly with synthetic materials.

Direct Dye

Direct dyes, also called substantive dyes, are unique because they do not require any additional chemicals or mordants to bind with the fabric. These are particularly effective on cellulose fibers, such as cotton and linen, where they easily adhere and provide a broad range of vibrant colors.
The application process involves dissolving the dye in water, after which the fabric is soaked in the solution. These dyes offer the advantage of being simple to apply at relatively low temperatures.

• Martius Yellow is an example of a direct dye, providing brilliant color.
• The ease of application makes direct dyes suitable for household and small-scale uses.

While the color fastness is not as high compared to mordant or acid dyes, their straightforward application and affordability make them highly accessible.