Animated Solution for Chemistry - Organic Chemistry: The correct match between items I and II is $\begin{array}{ll}\text{Item I (Mixture)}& \text{Item II (Separation method)}\\ \text{A. }{\text{H}}_2\text{O}:\text{Sugar}& \text{P. Sublimation}\\ \text{B. }{\text{H}}_2\text{O}:\text{Aniline}& \text{Q. Recrystallisation}\\ \text{C. }{\text{H}}_2\text{O}:\text{Toluene}& \text{R. Steam distillation}\\ & \text{S. Differential extraction}\end{array}$

Welcome to a classic exploration of chemical separation techniques! In this problem, we are presented with three distinct mixtures, each containing water paired with a different substance. Our mission is to act like chemical detectives and match each mixture with the perfect purification method based entirely on their unique physical properties.

We have Mixture A (Water and Sugar), Mixture B (Water and Aniline), and Mixture C (Water and Toluene). Let's break them down one by one and uncover the science behind their separation.

The Sweet Solution

First, let's focus on Mixture A, which consists of sugar dissolved in water. We know from everyday experience that sugar is a solid that dissolves completely in water, forming a homogeneous solution. Importantly, they do not react chemically with each other.

So, how do we separate a dissolved solid from a liquid? We exploit the concept of solubility. When we heat this mixture, the solubility of sugar increases dramatically, allowing us to create a highly saturated solution. If we then take this hot, saturated solution and cool it rapidly, the water can no longer hold all that dissolved sugar. The excess sugar precipitates out, forming beautiful, pure crystals.

This elegant and widely used process is called Recrystallisation. Therefore, Mixture A perfectly matches with method Q.

The Volatile Amine

Now let's move to Mixture B: water and aniline. Aniline is an organic liquid that is immiscible with water. If you mix them, they will form separate layers. However, aniline possesses a very special property that dictates our choice of separation technique.

Aniline is steam volatile. This means that when we pass steam through the mixture, the combined vapor pressure of the water and the aniline reaches atmospheric pressure at a temperature much lower than aniline's actual boiling point (which is quite high at $184^{\circ }\text{C}$).

By vaporizing at this lower temperature, we prevent the aniline from decomposing, which might happen if we tried to boil it directly. Therefore, to safely and effectively separate water and aniline, we use Steam Distillation. So, Mixture B matches with method R.

The Immiscible Hydrocarbon

Finally, let's examine Mixture C: water and toluene. Like aniline, toluene is an organic liquid that is completely immiscible with water. However, unlike aniline, toluene is not steam volatile in a way that requires complex distillation for basic separation.

Since these two liquids do not mix and naturally form two distinct layers based on their different densities (water is heavier and sits at the bottom, while toluene floats on top), we don't need any complex heating or vaporization. We can simply pour the mixture into a separating funnel, open the stopcock, and carefully drain the bottom water layer.

This straightforward, gravity-driven method is called Differential Extraction. So, Mixture C matches with method S.

Let's bring all our findings together. We have logically deduced that: - (A) matches with (Q) - (B) matches with (R) - (C) matches with (S)

Looking at our given options, this sequence perfectly aligns with option (a). This problem is a beautiful reminder of how understanding fundamental physical properties—like solubility, volatility, and density—allows us to solve practical chemistry challenges with elegance and precision!