Which Of The Following Is An Extensive Property Of Matter

Which of the Following is an Extensive Property of Matter? Understanding Extensive vs. Intensive Properties

The question, "Which of the following is an extensive property of matter?" often appears in chemistry and physics courses. Understanding the difference between extensive and intensive properties is crucial for comprehending the behavior of matter. This article will delve deep into this distinction, providing a comprehensive explanation with numerous examples to solidify your understanding. We will explore what constitutes an extensive property, contrasting it with intensive properties, and finally, provide you with a framework to easily identify each.

What are Extensive Properties?

Extensive properties are physical properties of matter that depend on the amount of matter present. In simpler terms, if you increase the amount of substance, the extensive property also increases proportionally. Think of it like this: if you double the amount of material, you double the value of the extensive property. Conversely, if you halve the amount, the value is halved as well.

Key Characteristics of Extensive Properties:

• Additive: The value of an extensive property for a system is the sum of the values for its constituent parts.
• Dependent on Amount: The magnitude changes directly with the amount of matter.
• Not Useful for Identification: Extensive properties alone cannot be used to identify a specific substance.

Examples of Extensive Properties:

• Mass: The amount of matter in an object. A larger object has a greater mass.
• Volume: The amount of space an object occupies. A larger object has a larger volume.
• Length: The linear dimension of an object. A longer object has a greater length.
• Weight: The force exerted on an object due to gravity. More mass means more weight.
• Energy: The capacity to do work. A larger system possesses more energy.
• Heat capacity: The amount of heat required to raise the temperature of a substance by a certain amount. A larger sample requires more heat.
• Entropy: A measure of disorder or randomness in a system. A larger system will generally have greater entropy.

What are Intensive Properties?

Intensive properties are physical properties of matter that are independent of the amount of matter present. These properties remain constant regardless of the sample size. They are inherent characteristics of the material itself.

Key Characteristics of Intensive Properties:

• Non-Additive: The value of an intensive property does not change when the system is divided into smaller parts.
• Independent of Amount: The magnitude is unaffected by the amount of matter.
• Useful for Identification: Intensive properties are often used to identify and characterize substances.

Examples of Intensive Properties:

• Temperature: A measure of the average kinetic energy of the particles in a substance. The temperature of a cup of water is the same as the temperature of a swimming pool full of water, assuming they are both at the same temperature.
• Density: Mass per unit volume. The density of gold remains the same whether you have a gold nugget or a gold bar.
• Pressure: Force per unit area. The pressure inside a tire remains constant regardless of the tire's size (assuming the same inflation).
• Melting Point: The temperature at which a solid changes to a liquid. The melting point of ice is always 0°C at standard pressure, regardless of the ice cube's size.
• Boiling Point: The temperature at which a liquid changes to a gas. The boiling point of water is always 100°C at standard pressure, regardless of the volume of water.
• Color: The wavelength of light reflected by a substance. A small piece of copper has the same color as a large piece of copper.
• Hardness: Resistance to scratching or indentation. The hardness of diamond is consistent regardless of the size of the diamond.
• Viscosity: Resistance to flow. The viscosity of honey remains the same whether you have a teaspoon or a gallon.
• Refractive Index: How much light bends when passing through a substance. The refractive index of glass is consistent regardless of the size of the glass piece.

Distinguishing Between Extensive and Intensive Properties: A Practical Approach

To determine whether a property is extensive or intensive, ask yourself: Does the value of the property change if I increase the amount of substance?

• If YES, it's an extensive property.
• If NO, it's an intensive property.

Specific Examples and Problem Solving

Let's consider a few examples to solidify this concept. Suppose you have a sample of pure water.

• Mass: If you double the amount of water, the mass doubles. Extensive.
• Temperature: If you double the amount of water (assuming both samples are at the same initial temperature), the temperature remains the same. Intensive.
• Volume: If you double the amount of water, the volume doubles. Extensive.
• Density: If you double the amount of water, the density remains the same (assuming constant temperature and pressure). Intensive.

Now let's tackle a multiple-choice question:

Question: Which of the following is an extensive property of matter?

a) Density b) Temperature c) Volume d) Boiling point

Answer: The correct answer is (c) Volume. As explained above, volume directly depends on the amount of substance present. Density, temperature, and boiling point are all intensive properties, remaining constant regardless of the sample size.

Beyond the Basics: Specific Heat Capacity as an Extensive Property

While specific heat capacity might seem like an intensive property because it describes the heat needed to raise the temperature of one gram or one mole of substance, it's crucial to remember the context. The specific heat capacity itself remains constant. However, when discussing the total heat capacity of a sample of the substance, it becomes extensive. A larger sample will require more heat to undergo the same temperature change; therefore, the total heat capacity is an extensive property.

Applications in Real-World Scenarios

The distinction between extensive and intensive properties is not merely an academic exercise. It has far-reaching implications in various fields:

• Chemical Engineering: Designing chemical reactors requires understanding how extensive properties like volume and mass influence reaction rates and yields. Intensive properties like temperature and pressure are critical parameters controlling reaction conditions.
• Material Science: Characterizing materials involves measuring both extensive and intensive properties. The size and shape (extensive) of a material affect its performance, but its fundamental properties like density and hardness (intensive) determine its suitability for specific applications.
• Thermodynamics: Extensive properties like internal energy and entropy are crucial in thermodynamic calculations, while intensive properties like temperature and pressure help define the state of a system.
• Environmental Science: Monitoring pollutants in the environment often involves measuring both extensive (total mass of pollutant) and intensive (concentration of pollutant) properties.

Conclusion: Mastering the Extensive-Intensive Distinction

Understanding the difference between extensive and intensive properties is fundamental to comprehending the physical and chemical behavior of matter. By mastering this distinction, you develop a more profound understanding of scientific principles and enhance your problem-solving abilities across various scientific disciplines. Remember the key: extensive properties change with the amount of matter, while intensive properties do not. Practice identifying properties using the techniques described above, and you'll confidently navigate the world of physical and chemical properties. This knowledge provides a solid foundation for more advanced studies in chemistry, physics, and engineering.