Question

An emulsifier is a substance which (a) helps dispersion of liquid in liquid (b) stabilises the emulsion (c) purifies the emulsion (d) coagulates the emulsion

Short answer

The correct answers are (a) helps dispersion of liquid in liquid, and (b) stabilises the emulsion.

Step-by-step solution

Understanding the role of emulsifier

An emulsifier is a substance that is capable of mixing two substances which are usually immiscible (not forming a homogeneous mixture when added together). The role of emulsifier often comes into play where it creates a stable, homogenous, and smooth mixture of water and oil

Analyzing the options

(a) helps dispersion of liquid in liquid: This is correct as emulsifiers do help in dispersing one liquid into another liquid which usually are immiscible. \n (b) stabilises the emulsion: This is also correct, as the primary function of an emulsifier is to stabilize the mixture of immiscible substances. \n (c) purifies the emulsion: This option is incorrect as the role of an emulsifier is not to purify the mixture but to stabilize and homogenize it \n (d) coagulates the emulsion: This is also incorrect as the function of an emulsifier is to stabilize the emulsion and not coagulate it.

Answer

Based on the understanding of the scientific concept of an emulsifier and analyzing the given options, it can be inferred that an emulsifier (a) helps dispersion of liquid in liquid, and (b) stabilises the emulsion, while the other two options are incorrect.

Key concepts

Dispersion of Liquids

Imagine trying to mix oil and water. What happens? They separate, with oil floating on top of the water. This is because these two liquids are immiscible, meaning they do not naturally blend into a homogenous mixture. Dispersion of liquids involves breaking one of these liquids into tiny droplets so that it can spread throughout another liquid.

This is where the magic of emulsifiers comes in. Emulsifiers are substances that help disperse one immiscible liquid into another, such as oil in water, by reducing the surface tension between the liquids.

• They have a unique molecular structure, with one end that loves water (hydrophilic) and another that loves oil (lipophilic).
• This special structure allows emulsifiers to coat oil droplets and keep them suspended in water, effectively dispersing them.

Think of emulsifiers as a bridge connecting two friends who normally wouldn't hang out — oil and water. Therefore, emulsifiers greatly aid in the effective dispersion of liquids.

Emulsion Stability

Once a liquid is dispersed in another — thanks to our helpful emulsifier — the goal is to keep it that way. This is known as emulsion stability.

Emulsifiers play a valuable role in ensuring the stability of the mixture. Without them, the tiny droplets of one liquid might eventually coalesce, or come back together, causing separation. Emulsion stability ensures that these droplets stay finely balanced without merging.

• By surrounding each droplet, emulsifiers prevent them from coming back together.
• This stabilizing action makes it possible to maintain a consistent and unified mixture, crucial in various applications.

In food products, for instance, this stability helps in creating creamy dressings and smooth ice creams. In cosmetics, it ensures lotions and creams keep their silky texture. Thus, emulsifiers are essential in maintaining the beauty of a well-blended emulsion.

Immiscible Liquids

Immiscible liquids are liquids that do not mix to form a homogeneous solution. Simply put, they are like incompatible classmates sitting in different corners of the room. Common examples include oil and water.

The challenge with immiscible liquids is that due to their differing properties, particularly in terms of polarity, they naturally repel each other. This is why, when mixed together, they separate, creating layers based on density.

• This separation is because of the lack of a common interface that can balance both liquids' chemical structures.
• Emulsifiers are introduced to bridge this gap by offering a common interface, enabling a more harmonious mixture.

By understanding immiscible liquids, we can appreciate the work emulsifiers do in bringing together these once incompatible liquids to form useful and stable emulsions. This knowledge helps in formulation across industries, from culinary arts to pharmaceuticals.