In colloid chemistry, butter is an example of which type of colloid, formed when which phase is dispersed in which medium?

Introduction / Context:
Colloids are mixtures in which one substance is finely dispersed in another, and they play an important role in food science, medicine, and many industrial applications. Emulsions are a special class of colloids where both phases are liquids, such as oil and water. Everyday foods like butter, milk, and cream are classic exam examples used to test understanding of colloid types. This question asks specifically what type of colloid butter represents and which phase is dispersed in which medium.

Given Data / Assumptions:

• Butter is a semi solid food product obtained from milk or cream.
• The options mention proteins in water, water dispersed in fat, fat globules dispersed in water, and carbohydrates dissolved in water.
• We assume typical household butter, not special low fat spreads or margarines.
• The focus is on the physical state and distribution of water and fat in butter.

Concept / Approach:
Milk and cream are examples of oil in water emulsions, in which fat globules are dispersed in a continuous water phase. When cream is churned to form butter, the structure changes. The continuous phase becomes fat, and small droplets of water remain trapped inside. This type of colloid is called a water in oil emulsion, because water is the dispersed phase and oil or fat is the continuous medium. Proteins and carbohydrates are also present in dairy products, but they are not the main factor in classifying butter as a particular colloid type. Therefore, butter is best described as water droplets dispersed in fat, forming a water in oil emulsion.

Step-by-Step Solution:
Step 1: Recall that emulsions involve two immiscible liquids, typically oil and water, where one is dispersed as droplets in the other. Step 2: Recognise that in milk and cream, fat droplets are distributed in a mostly aqueous environment, making them oil in water emulsions. Step 3: Understand that during the churning process that produces butter, fat globules coalesce to form a continuous fat phase. Step 4: Note that in butter, small droplets of water remain dispersed inside this fat matrix. Step 5: Conclude that butter is a water in oil emulsion, where water droplets are dispersed in fat, and select that description as the correct answer.

Verification / Alternative check:
Food science sources describe butter as a classic water in oil emulsion with a fat content typically around 80 percent and the remainder mostly water and milk solids. Microscopic examination shows small water droplets distributed throughout a continuous fat network. This structure explains butter behaviour: it melts to release fat and some water, and it does not mix easily with water until emulsifiers are added. These observations are consistent with the description of butter as water dispersed in fat and do not match the other proposed colloid types in the options.

Why Other Options Are Wrong:
The option describing proteins dispersed in water refers more to sols such as protein solutions, not to butter, which is mainly fat. The option stating that fat globules are dispersed in water describes milk or cream, not butter. Carbohydrates dissolved in water form true solutions, not colloidal emulsions, and do not reflect the structure of butter. Therefore, these alternatives do not correctly describe the colloid type and phase distribution in butter.

Common Pitfalls:
A frequent source of confusion is mixing up the colloid type for milk and butter, since both are dairy products. Students sometimes remember that milk is an emulsion and wrongly extend the same description to butter. Another pitfall is ignoring which phase is continuous and which is dispersed, which is crucial for distinguishing oil in water from water in oil emulsions. To avoid these mistakes, remember the simple rule: milk is oil in water, butter is water in oil. With this pattern in mind, similar exam questions become easier to answer accurately.

Final Answer:
Butter is a colloid in which water droplets are dispersed in fat to form a water in oil emulsion.