Which Of The Following Is An Intensive Property

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

Understanding the difference between intensive and extensive properties is crucial in various fields, from chemistry and physics to materials science and engineering. This article will delve deep into the definition, examples, and applications of intensive properties, helping you clearly differentiate them from extensive properties. We'll explore how this distinction impacts various scientific calculations and analyses. By the end, you'll be confident in identifying intensive properties and applying this knowledge effectively.

Intensive Properties: Definition and Characteristics

An intensive property is a physical property of a system that does not depend on the system's size or the amount of matter present. This means its value remains constant regardless of whether you're considering a small sample or a large quantity of the substance. In simpler terms, it's a property that is intrinsic to the material itself.

Here's a breakdown of the key characteristics of intensive properties:

• Independent of mass or amount: This is the defining characteristic. Whether you have a gram or a kilogram of gold, its density remains the same.
• Constant throughout the system: An intensive property has a uniform value throughout a homogeneous system.
• Useful for identifying substances: Many intensive properties, like density and boiling point, are unique to specific substances and can be used for identification purposes.
• Often used in calculations: Intensive properties are essential inputs in various thermodynamic and material science calculations.

Extensive Properties: A Contrast

To fully grasp the concept of intensive properties, let's briefly contrast them with extensive properties. Extensive properties do depend on the amount of matter present. Their values change proportionally with the size of the system.

Examples of extensive properties include:

• Mass: The amount of matter in a substance.
• Volume: The space occupied by a substance.
• Length: A linear measurement of a substance.
• Energy: The capacity to do work or produce heat.
• Heat capacity: The amount of heat required to raise the temperature of a substance by a certain amount.

The key difference lies in the fact that if you divide an extensive property in half, its value is also halved. This is not the case with intensive properties.

Examples of Intensive Properties: A Comprehensive List

Let's explore a wide range of intensive properties, categorized for clarity:

Physical Intensive Properties

• Density: Mass per unit volume (ρ = m/V). A fundamental intensive property that distinguishes different substances. For example, the density of water is approximately 1 g/cm³.
• Temperature: A measure of the average kinetic energy of particles in a system. Temperature remains constant throughout a system in thermal equilibrium.
• Pressure: Force per unit area. Pressure is often expressed in units like Pascals (Pa) or atmospheres (atm). In a closed container, pressure is uniform throughout.
• Boiling point: The temperature at which a liquid changes to a gas at a given pressure. The boiling point of water at standard atmospheric pressure is 100°C.
• Melting point: The temperature at which a solid changes to a liquid at a given pressure. Each substance has a unique melting point.
• Viscosity: A measure of a fluid's resistance to flow. Highly viscous fluids like honey flow more slowly than less viscous fluids like water.
• Refractive index: A measure of how much light bends when it passes from one medium to another. The refractive index is used in various optical instruments.
• Hardness: Resistance to scratching or indentation. Hardness is often measured using scales like the Mohs hardness scale.
• Color: The visual perception of light reflected by a substance. Color can be used to distinguish substances but can also depend on lighting conditions.
• Odor: The scent associated with a substance. Odor is subjective, depending on individual perception.
• Taste: The sensation experienced when a substance is in contact with taste buds. Similar to odor, it's subjective and depends on individual perception.
• Specific heat capacity: The amount of heat required to raise the temperature of one unit mass of a substance by one degree Celsius.

Chemical Intensive Properties

• pH: A measure of the acidity or basicity of a solution. The pH scale ranges from 0 to 14, with 7 representing neutral.
• Molarity: Concentration expressed as moles of solute per liter of solution.
• Molality: Concentration expressed as moles of solute per kilogram of solvent.
• Specific gravity: The ratio of the density of a substance to the density of a reference substance (usually water).
• Solubility: The maximum amount of solute that can be dissolved in a given amount of solvent at a specific temperature and pressure.

Applications of Intensive Properties

The utility of intensive properties extends across numerous scientific disciplines and applications:

• Material Identification: Intensive properties like density, melting point, and boiling point are crucial for identifying unknown substances in chemistry and materials science.
• Process Control: In chemical engineering and manufacturing, monitoring intensive properties like temperature and pressure is essential for controlling and optimizing chemical reactions and processes.
• Phase Diagrams: Intensive properties such as temperature and pressure are used to construct phase diagrams, which illustrate the conditions under which different phases of a substance (solid, liquid, gas) exist.
• Thermodynamics: Intensive properties are essential for thermodynamic calculations and understanding the behavior of systems under different conditions.
• Fluid Mechanics: Intensive properties like viscosity and density are crucial in understanding the flow and behavior of fluids.
• Material Selection: Engineers use intensive properties to select materials with desired characteristics for different applications. For instance, choosing a material with high tensile strength for structural components.

Differentiating Intensive from Extensive Properties: Practical Examples

Let's illustrate the difference with some practical examples:

Scenario 1: Water

• Extensive: 1 liter of water has a mass of approximately 1 kilogram. 2 liters of water has a mass of approximately 2 kilograms. The mass is an extensive property.
• Intensive: Both 1 liter and 2 liters of water have a density of approximately 1 g/cm³. Density is an intensive property.

Scenario 2: Gold

• Extensive: A 10-gram gold bar occupies a specific volume. A 20-gram gold bar occupies twice that volume. Volume is an extensive property.
• Intensive: Both the 10-gram and 20-gram gold bars have the same density, melting point, and color. These are intensive properties.

Intensive Properties and Phase Transitions

During phase transitions (e.g., melting, boiling), intensive properties often change abruptly. For example, during the melting of ice, the temperature remains constant at 0°C (at standard pressure) even though heat is being added. The temperature is an intensive property that doesn't change during the phase transition itself.

Calculating Intensive Properties from Extensive Properties

While intensive properties are independent of the amount of matter, they can often be calculated using extensive properties. For example:

• Density (intensive) = Mass (extensive) / Volume (extensive)

This demonstrates that the relationship between extensive and intensive properties is not a direct contradiction; intensive properties are derived from the ratio of two extensive properties.

Conclusion: The Importance of Understanding Intensive Properties

Understanding the distinction between intensive and extensive properties is fundamental to comprehending the physical and chemical behavior of matter. Intensive properties are invaluable for identifying substances, designing processes, and making calculations across numerous scientific and engineering disciplines. The ability to distinguish between these property types forms the cornerstone of advanced scientific analysis and practical application. Remember that intensive properties are intrinsic to the material itself, making them key indicators of its identity and behavior regardless of the sample size. Mastering this concept opens the door to a deeper understanding of the material world.