Problem 9 - Advanced Problems in Physical Chemistry for Competitive Examinations

Question

Which of the following pair does show the extensive properties? (a) temperature and pressure (b) viscosity and surface tension (c) refractive index and specific heat (d) volume and heat capacity

Step-by-Step Solution

Answer

The pair that shows extensive properties is (d) volume and heat capacity.

Step 1: Understanding Extensive Properties

Identify what extensive properties mean. Extensive properties are properties that depend on the amount of matter present in a sample. They change when the size or the amount of the sample changes.

Step 2: Analyzing Each Pair

Go through each pair and determine whether each property is an extensive property that depends on the amount of matter: (a) temperature and pressure are not extensive; they are intensive. (b) viscosity and surface tension are also intensive. (c) refractive index is intensive, but specific heat is extensive. (d) volume and heat capacity are both extensive.

Step 3: Identifying the Correct Pair

From the analysis, identify the pair where both properties are extensive. In this case, it is option (d) volume and heat capacity.

Key Concepts

Physical Chemistry

Physical chemistry is a branch of chemistry concerned with the underlying principles that govern the properties and behavior of matter. It closely intertwines with the laws of physics, especially when it comes to understanding atomic and molecular structures and dynamics. This field has profound implications for studying and manipulating chemical reactions, understanding the energy transfer, and the development of new technologies.

For example, when analyzing the extensive properties of substances, a physical chemist considers the relationships between energy and matter on a molecular and atomic scale. This allows the chemist to predict how substances will behave when scaled up from laboratory amounts to commercial quantities. Understanding concepts such as extensive and intensive properties is just a small piece of the complex puzzle that physical chemists deal with every day.

Intensive vs Extensive Properties

Understanding the difference between intensive and extensive properties is crucial in physical chemistry. Intensive properties are characteristics of matter that do not change with the amount of substance present. These include properties like temperature, pressure, viscosity, and surface tension. No matter how much substance you have, these properties stay consistent, making them key for identifying substances.

On the other hand, extensive properties are dependent on the amount of matter present. These include volume, mass, and heat capacity. If you take a sugar cube and divide it into two pieces, each piece will have half the mass and volume of the original cube, showcasing the extensive nature of these properties.

These concepts are not just academic: they have practical implications. For instance, a chemical engineer must understand these properties when designing a large-scale industrial process to ensure the desired substance is produced efficiently and safely.

Chemistry Competitive Examinations

For students aspiring to excel in the field of chemistry, competitive examinations are a critical step. These exams often feature questions that test the understanding of intensive and extensive properties to evaluate a student's grasp of fundamental concepts in chemistry. It is important to not only memorize which properties are intensive or extensive but also to understand why.

In competitive exams, the ability to analyze a problem, interpret data, and apply theoretical principles to practical scenarios is key. For instance, a question may ask you to identify extensive properties in a given list, as seen in the exercise provided. Success in these exams opens doors to prestigious education institutions and can lay the groundwork for a career in chemical research, industry, or academia. Therefore, a deep comprehension of these basic principles can provide a competitive edge to students.