Chapter 15, Problem 69A

(a)

Interpretation Introduction

Interpretation: Whether a solution containing table sugar or table salt dissolved in water can be differentiated by visual inspection or not needs to be explained.

Concept Introduction: The dissolution of solute in the solvent depends on the principle of “like dissolve like”. Here, polar solutes are soluble in polar solvents and non-polar solutes are soluble in a non-polar solvent.

Explanation of Solution

Both table sugar and table salt are soluble in water. This is because water is a polar solvent and both sugar and salt are polar solutes. When sugar is put in water, sugar molecules get dissociated and dispersed throughout the water. The dispersed particles of sugar are very small and cannot be seen by naked ice. On the other hand, table salt is sodium chloride which is an ionic compound. Being polar in nature, it gets completely dissolved in water. Since there is no change in color takes place when salt and sugar are dissolved in water. Also, the particles of sugar and salt cannot be seen. Thus, it is not possible to differentiate salt and sugar solutions by visual inspection.

(b)

Interpretation Introduction

Interpretation: Two ways by which a solution containing table sugar or table salt dissolved in water can be easily differentiated needs to be given.

Concept Introduction: The dissolution of solute in the solvent depends on the principle of “like dissolve like”. Here, polar solutes are soluble in polar solvents and non-polar solutes are soluble in a non-polar solvent.

Explanation of Solution

The two by which a solution containing table sugar or table salt dissolved in water can be easily differentiated are as follows:

1. Salt solution can conduct electricity because sodium chloride gets dissociated into sodium and chloride ions in water. On the other hand, sugar solution does not have any ions thus, it cannot conduct electricity.
2. Salt solution and sugar solution can be differentiated by tasting. Salt solution tastes sour but the sugar solution tastes sweet.