Question

Name a suitable technique of separation of the components from a mixture of calcium sulphate and camphor.

Short answer

Use sublimation to separate camphor from calcium sulphate.

Step-by-step solution

Identify the Properties of Components

Start by identifying the key properties of the components in the mixture. Calcium sulphate is a solid inorganic compound that does not sublimate easily, while camphor is an organic compound that sublimes at room temperature.

Understand Sublimation

Because camphor can sublimate, it will convert directly from a solid to a gas when heated gently, which can separate it from non-sublimating components like calcium sulphate.

Choose Sublimation Technique

Based on the properties identified, use sublimation as the technique to separate camphor from calcium sulphate. Heat the mixture gently and collect the camphor vapors as they cool back into a solid, leaving behind the calcium sulphate.

Key concepts

Sublimation

Sublimation is a fascinating phase transition process where a substance changes directly from a solid to a gas without passing through the liquid state. This is a unique property exhibited by only certain substances. During sublimation:

• The substance absorbs heat, causing its particles to gain enough energy to overcome intermolecular attractions.
• It then transforms directly into a gaseous state.
• This process can be reversed, where the gas deposits back into a solid, skipping the liquid phase again, a process known as deposition.

This technique is particularly useful in separation processes where a mixture contains a sublimable component. By heating the mixture gently, the sublimable substance transforms into vapor, which can then be collected and condensed back into a solid. This leaves behind the non-sublimable solid components of the mixture.

Calcium Sulphate

Calcium sulphate, chemically represented as \( CaSO_4 \), is a widely occurring inorganic compound. It's commonly known in its dehydrate form as gypsum, and in its anhydrous form, as anhydrite. Here are some notable characteristics of calcium sulphate:

• It is a white, crystalline, and non-volatile compound.
• Calcium sulphate does not sublimate; hence, it remains in solid form when exposed to heat.
• This property makes it ideal for separation through sublimation, as it ensures that calcium sulphate does not transition to a gas while camphor does.
• It is often used in construction, as a soil conditioner, and as a food additive.

In separation processes involving a mixture with a sublimable component, calcium sulphate's non-sublimable nature ensures it remains as the residue after the sublimation of compounds like camphor.

Camphor

Camphor is a waxy, flammable solid that is best known for its aromatic properties. This organic compound has several interesting properties:

• Camphor sublimes at room temperature, releasing a strong, penetrating fragrance.
• It is frequently used in medicinal products for its numbing and antiseptic qualities.
• In a mixture, camphor can be separated via sublimation, as it easily converts from solid to gas when gently heated.
• This makes it an ideal candidate for separation techniques that rely on phase changes.

In mixtures like calcium sulphate and camphor, heating causes camphor to sublimate. The gaseous camphor is then captured and condensed, returning it to a solid form, effectively separating it from non-sublimable substances.