Problem 16 - A Complete Resource Book in Chemistry for JEE Main

Question

Which method is used for the separation of two immiscible liquids? (a) chromatography (b) fractionating column (d) fractional distillation (c) separating funnel

Step-by-Step Solution

Answer

(c) Separating funnel is used for the separation of two immiscible liquids.

Step 1: Understand the Nature of the Liquids

Two immiscible liquids are those that do not mix together and form two separate layers when combined. This is usually seen with liquids like oil and water.

Step 2: Identify the Suitable Separation Method

Since the liquids do not mix and naturally form layers, a method that can take advantage of this layering is preferred. A separating funnel is specifically designed for this purpose, as it allows the denser liquid to be drained out from underneath the less dense liquid.

Step 3: Learn How a Separating Funnel Works

A separating funnel is a piece of laboratory equipment that features a tap at the bottom. When the liquids settle, the denser liquid can be released by opening the tap and collected separately from the less dense liquid that remains.

Step 4: Match the Method to the Options

Among the given options, the separating funnel (option c) is the correct device to separate immiscible liquids, as chromatography, fractionating columns, and fractional distillation are suited for homogenous mixtures or miscible liquids.

Key Concepts

Immiscible Liquids

Immiscible liquids are liquids that do not mix with each other; instead, they form distinct layers. A classic example of immiscible liquids is oil and water. When two such liquids are put together in a container, they will separate based on their densities. The denser liquid forms the bottom layer, and the less dense liquid makes up the top layer.

The inability of immiscible liquids to mix is primarily due to the different types of molecular bonding in the liquids.

• Typically, one liquid is polar (like water), and the other is non-polar (like oil).
• Polar molecules have a slight charge, allowing them to bond well with each other but not with non-polar molecules.

Understanding which liquids are immiscible is crucial for choosing the correct separation technique in both laboratory and industrial settings.

Separating Funnel

A separating funnel is a specialized piece of laboratory equipment used to separate immiscible liquids. It is a cone-shaped container with a stopcock at the bottom. This design allows for the controlled release of the liquid layers.

To use a separating funnel:

• Pour the mixture of immiscible liquids into the funnel.
• Allow the liquids to settle until they form distinct layers.
• Open the stopcock to drain the denser liquid into another container, leaving the less dense liquid behind.

This tool is invaluable when you need to obtain pure samples of each liquid, and its simple mechanism makes it highly effective and easy to use for both beginners and experienced chemists.

Laboratory Equipment

In the context of separation techniques, laboratory equipment like separating funnels plays a significant role in efficiently achieving the separation objectives. Each type of laboratory tool is designed with a specific function in mind for accurate experimental results.

Here's why it's important to choose the right equipment:

• Separation accuracy: Using the appropriate equipment ensures that the separation process is accurate.
• Safety: Proper equipment ensures that the procedure is conducted safely.
• Efficiency: Adequate tools make the separation process quicker and with higher yields.
• Reproducibility: Good equipment allows for consistent replication of results across different experiments.

In addition to separating funnels, there are many other specialized pieces of equipment like pipettes, beakers, and Bunsen burners, each supporting various aspects of laboratory work.