Problem 5 - A Complete Resource Book in Chemistry for JEE Main

Question

A mordant binds the fabric through (a) coordinate bonds (b) covalent bonds (c) ionic bonds (d) H-bonds

Step-by-Step Solution

Answer

The mordant binds the fabric through coordinate bonds.

Step 1: Define the Problem

We need to identify the type of chemical bond a mordant forms with fabric when dyeing. A mordant is a substance used to set dyes on fabrics by forming a coordination complex with the dye, which then attaches to the fabric.

Step 2: Identify the Possible Types of Bonds

The exercise provides four potential types of bonds: coordinate bonds, covalent bonds, ionic bonds, and hydrogen bonds. Each bond type involves different interaction forces and atom exchanges.

Step 3: Understand Coordinate Bonds

A coordinate bond, or dative covalent bond, forms when one atom provides both electrons for a bond. Mordants often work through coordination by interacting with metal ions that can form such bonds with dyes.

Step 4: Analyze Mordant's Bonding Mechanism

In the context of dyeing, mordants typically form coordinate bonds with fabric and dye molecules because they create stable complexes with the dye that attaches to the fiber, ensuring color fastness.

Step 5: Conclude the Relationship Type

Based on the analysis, mordants primarily use coordinate bonds to bind with fabric during the dyeing process, enhancing the fixation of the dye.

Key Concepts

Coordinate Bonds

When discussing chemical bonding in dyeing, it's important to understand coordinate bonds. A coordinate bond is a type of covalent bond, specifically known as a dative covalent bond. What distinguishes it from a standard covalent bond is that both of the shared electrons come from the same atom. This makes coordinate bonds somewhat special because one atom is effectively hosting both electrons while the other atom is only a participant.
In the process of dyeing, coordinate bonds are particularly valuable due to their stability and strength. They help in forming stable associations between dye molecules and metal ions present in mordants. These bonds are crucial as they create a secure attachment which is necessary for the dye to adhere to the fabric efficiently. Therefore, if a mordant is involved, coordinate bonds play a central role in ensuring the dye's durability and colorfastness on the material.

Mordants in Dyeing

Mordants are substances used in the dyeing process to set dyes on fabrics. Their main function is to form a link between the dye and the fabric, ensuring the dye is securely attached to the textile.
Mordants are typically metal salts, including calcium, aluminum, and chromium, which can easily form bonds with both dye molecules and fabric ions. By creating a chemical bridge through coordinate bonds, mordants ensure that the dye does not wash out or fade quickly.

• Mordants work by improving the adhesion of the dye to the fabric.
• They increase the dye’s color fastness properties.
• They are crucial for processes where vibrant and durable colors are required.

Through their application, mordants help achieve a deeper color and enhance the fabric’s resistance to water and sunlight. Mordants are thus an essential component for high-quality textile dyeing.

Coordination Complexes

Coordination complexes are central to the dyeing process as they involve the interaction of metal ions and molecules like dyes. A coordination complex consists of a central atom or ion, usually a metal, and surrounding molecules or ions known as ligands.
These ligands, which can be dyes, attach to the central metal through coordinate bonds. In the world of fabric dyeing, the creation of these complexes is critical.

• The metal ions in the mordant act as a bridge between the dye and the fabric.
• This interaction enhances the stability and attachment of the dye.
• This contributes to long-lasting and vibrant colors on the fabric.

From a chemistry perspective, coordination complexes provide an intricate but highly effective means of maintaining the dye's adherence and longevity on textiles. By understanding the role of coordination complexes, one comprehends how dyes achieve incredible color retention and saturation.