Problem 33 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

A system is said to be \(\ldots \ldots \ldots \ldots \ldots .\) if it can neither exchange matter nor energy with the surroundings.

Step-by-Step Solution

Answer

An isolated system.

Step 1: Understand the System Types

Systems in thermodynamics can be classified based on their ability to exchange energy and matter with their surroundings. The three main types are open, closed, and isolated systems. We need to identify which of these cannot exchange either energy or matter.

Step 2: Define an Isolated System

An isolated system is one that does not exchange energy or matter with its surroundings. This means it's completely sealed off.

Step 3: Identify the Correct Term

Based on the definition from Step 2, the system described in the exercise is an isolated system because it cannot exchange either matter or energy with its surroundings.

Key Concepts

Thermodynamic Systems

Thermodynamic systems are defined as a quantity of matter or a region in space chosen for the purpose of study. These systems can vary by their capacity to exchange energy and matter with their surroundings. There are three primary types of thermodynamic systems:

• Open Systems: These can exchange both matter and energy with their environment. For example, boiling water in an open pot allows steam to escape, exchanging both heat and water with the air.
• Closed Systems: These systems allow the exchange of energy (like heat or work) but not matter. A pressure cooker is an example, where heat from the stove enters the pot, but the steam is mostly contained.
• Isolated Systems: These do not allow any exchange of energy or matter. A perfect thermos bottle, ideally, neither loses heat to its environment nor allows external energy in.

Understanding these systems helps in grasping how energy and matter interact within different settings and is fundamental in thermodynamics.

Energy Exchange

Energy exchange in thermodynamics refers to how energy in various forms moves in and out of a system. This can occur in numerous ways, including heat transfer and work.

• Heat Transfer: This is the movement of thermal energy due to temperature differences. Heat moves from a warmer area to cooler surroundings until temperature balance is reached.
• Work: In thermodynamic terms, work relates to processes causing a system to change its state (like expanding or compressing gases in a piston).

In an isolated system, no energy transfer occurs; energy remains constant within the system. This makes isolated systems a valuable model for understanding the conservation of energy principle.

Matter Exchange

Matter exchange concerns the movement of substances in and out of a system's boundaries. In open systems, matter flows freely across the borders, impacting the system's mass, volume, or composition.

• Open Systems: Matter can be added or removed, affecting the system's content. A simple example is the evaporation of sweat, which removes water molecules from the body.
• Closed Systems: These systems retain matter. The amount and type of material inside do not change, although energy can enter or leave.
• Isolated Systems: Neither matter nor energy crosses its borders. There's no change in system characteristics unless internal processes occur.

Understanding matter exchange is crucial in processes like chemical reactions, where stoichiometry relies on tracking substance quantities.