Problem 54 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following propertes of liquids is concerned with internal resistance to its flow? (a) viscosity (b) parachore value (c) refractive index (d) surface tension

Step-by-Step Solution

Answer

The property concerned with internal resistance to flow in liquids is viscosity (option a).

Step 1: Understand the Question

The question asks us to identify a property of liquids that is related to their internal resistance to flow. We are given four options, out of which we need to select the one that best matches the description.

Step 2: Analyze the Options

Let's examine each of the four options: (a) **Viscosity**: This property measures a liquid's resistance to flow. Higher viscosity indicates higher internal resistance. (b) **Parachore value**: This is a measure related to molecular volume and is not commonly associated with resistance to flow. (c) **Refractive index**: This measures how much light bends as it passes through a substance and is unrelated to flow resistance. (d) **Surface tension**: This is a measure of the cohesive forces at a liquid's surface, affecting shape and bead formation, not internal flow resistance.

Step 3: Identify the Correct Property

Based on the analysis in Step 2, option (a) viscosity is directly concerned with a liquid's internal resistance to flow. It is the most appropriate choice among the options given.

Key Concepts

Viscosity

Viscosity is a fundamental property of liquids that describes their resistance to flow. Imagine trying to pour honey from a jar compared to water. Honey moves much slower because it has a higher viscosity.
The concept of viscosity signals how thick or thin a liquid is. A high-viscosity liquid, like honey, deforms slowly, whereas a low-viscosity liquid, like water, flows quickly.

• Measurement of Viscosity: The viscosity of a liquid is often measured in units like poise or pascal-seconds. Different instruments, such as viscometers, can help determine a liquid's viscosity.
• I mpact on Everyday Life: Viscosity affects everything from the choice of motor oil for your car to the design of industrial processes.

Understanding viscosity can help predict how substances will behave when mixed or processed, making it crucial in areas like food science and engineering.

Internal Resistance

The internal resistance of a liquid is intimately connected to viscosity. When we talk about a liquid's internal resistance, we're exploring what makes it resist movement or flow.
Every liquid contains molecules that exert forces on each other. This interaction can either facilitate flow or hinder it.

• Force Interaction: In liquids with high internal resistance (high viscosity), molecules experience stronger attractive forces, leading to slower movement.
• Temperature Influence: Temperature can affect internal resistance. Heating a liquid often reduces its viscosity, making it flow more easily.

Thus, understanding internal resistance gives us insights into how different liquids will act under varying conditions.

Liquid Flow

Liquid flow is the movement of liquid particles past one another, a process influenced by viscosity and internal resistance. This flow can be linear or turbulent depending on a few factors.
Key elements affecting liquid flow include:

• Velocity: Higher flow rates often lead to more friction between liquid layers, impacting overall movement.
• Pressure: Differences in pressure can drive the motion of a liquid from high to low-pressure areas, dictating the rate of flow.

The study of liquid flow is crucial in designing systems like pipelines or irrigation channels. By understanding how easily or difficultly a liquid flows, engineers can develop optimized systems that maximize efficiency and minimize energy consumption.