Chapter 2, Problem 81A

Interpretation Introduction

Interpretation: The method of separation of sand from a mixture of charcoal, sand, sugar, and water needs to be explained.

Concept Introduction: The separation of a substance from a mixture containing more than two substances depends on their solubility as well as comparative density.

Explanation of Solution

The given mixture contains charcoal, sugar, sand, and water. Here, sugar is soluble in water and other substances can form layers in water depending on their respective densities. Here, sugar is soluble in water thus, it does not form any layer but gets completely dissolved in water. Now, charcoal and sand both are insoluble in water, the density of sand and charcoal are combatively more than water thus, they form separate layers in the water. In comparing the densities of charcoal and sand, sand is denser than charcoal. Therefore, sand is at the bottom layer of the water. Also, charcoal is denser than water but still, it floats in water due to its porous structure.

Now, sugar is dissolved in water thus, there will be three layers; charcoal, water, and sand. The charcoal floats in water thus, it forms the first layer followed by the water and sand layer. Here, charcoal can be separated by decanting the topmost layer of solution using a beaker. Sand is at the bottom of the beaker and can be separated by a simple filtration method.