Question

How would you separate a mixture of sugar and sand and isolate each in its pure form?

Short answer

Dissolve the mixture in water, filter to separate the sand, dry the sand, then evaporate the water to obtain pure sugar.

Step-by-step solution

- Dissolve the Mixture in Water

Add the mixture of sugar and sand to a container filled with water. Stir the mixture to allow the sugar to dissolve completely in the water. Sand will not dissolve and will settle at the bottom.

- Filter the Mixture

Use a filtration setup (filter paper and funnel) to separate the sand from the sugar solution. Pour the mixture through the filter paper placed in a funnel. The sand will remain on the filter paper as a residue, and the sugar solution will pass through into a collecting container.

- Dry the Sand

Collect the sand residue from the filter paper and place it on a flat surface. Allow it to dry completely to obtain pure, dry sand.

- Evaporate the Water from the Sugar Solution

Heat the sugar solution gently in a clean container to evaporate the water. As the water evaporates, sugar crystals will be left behind. Ensure the heating is done carefully to prevent burning the sugar.

- Collect Pure Sugar

Once all the water has evaporated, collect the sugar crystals from the container. The sugar is now in its pure form.

Key concepts

Filtration

Filtration is a common method used to separate solid particles from liquids. In our exercise, filtration helps separate sand from a mixture of sugar and water.
Here's how it works:

• **Setup**: You'll need a funnel and filter paper. Place the filter paper in the funnel.
• **Action**: Pour the mixture of sugar, sand, and water through the funnel. The filter paper will trap the sand particles.
• **Collection**: The sand will remain on the filter paper as residue. The liquid sugar solution will pass through into a separate container.

Filtration is effective for separating insoluble substances like sand from soluble ones like sugar.

Evaporation

Evaporation is the process of turning a liquid into vapor. In our exercise, we use evaporation to separate sugar from water.
Here's the process:

• **Heat**: Heat the sugar solution gently in a clean container.
• **Vaporize**: The water will start turning into vapor.
• **Leave Residue**: Sugar, which is not volatile, will not vaporize and will be left behind as crystals.

Be careful when heating to avoid burning the sugar. This step ensures we obtain pure sugar crystals.

Pure Substances

Pure substances consist of a single type of element or compound. In our exercise, the goal is to obtain pure sand and pure sugar.

• **Sand**: After filtering, the sand collected on the filter paper, once dried, becomes pure sand.
• **Sugar**: After evaporating the water, the remaining crystals are pure sugar.

Pure substances have fixed composition and distinct properties, such as melting point, boiling point, and solubility.

Solubility

Solubility refers to a substance's ability to dissolve in a solvent. In our exercise, we exploit the different solubility of sugar and sand.

• **Dissolving Sugar**: Sugar is highly soluble in water, which means it dissolves completely when stirred. This helps in separating it from sand.
• **Sand's Insolubility**: Sand does not dissolve in water and remains as solid particles.

This differential solubility helps in the separation process. The water soluble sugar gets separated from the non-soluble sand, making it easier to isolate each component in its pure form.