Problem 6 - A Complete Resource Book in Chemistry for JEE Main

Question

Plants and living beings are examples of (a) isolated system (b) adiabatic system (c) open system (d) closed system

Step-by-Step Solution

Answer

Plants and living beings are examples of an open system.

Step 1: Define the Systems

There are four types of thermodynamic systems: Open, Closed, Isolated, and Adiabatic. An Open System can exchange both matter and energy with its surroundings. A Closed System can only exchange energy, not matter. An Isolated System cannot exchange either energy or matter with its surroundings. An Adiabatic System is a type of closed system that specifically has no heat exchange.

Step 2: Analyze Plants and Living Beings

Plants and living beings are capable of exchanging both matter (like gases and nutrients) and energy (like heat and light) with their surroundings. This interaction is primarily through respiration and photosynthesis in plants, and respiration in animals.

Step 3: Match the Characteristics

Based on Step 2, since plants and living beings exchange both matter and energy with their environment, they are classified as Open Systems.

Step 4: Select the Correct Answer

With the understanding from the previous steps, determine which option correctly describes plants and living beings. Since they are open systems, the correct option is (c) open system.

Key Concepts

Open System

An open system in thermodynamics can freely exchange both matter and energy with its surrounding environment.
This is a key characteristic that distinguishes it from other types of systems.

• Examples include the human body, which exchanges gases like oxygen and carbon dioxide through respiration.
• Plants fit this classification because they exchange gases with the atmosphere and capture energy from sunlight.

In essence, open systems are dynamic and interact with their environment through processes that involve energy transfer and material exchange. This interaction allows for adaptive and life-sustaining processes such as photosynthesis in plants and metabolic activities in living organisms.

Closed System

A closed system is a type of thermodynamic system that can exchange energy but not matter with its surroundings.
While energy can be transferred in the form of heat or work, the matter within the system remains constant.

• Think of a sealed steam turbine where steam circulates, transferring energy to produce work without the steam itself escaping.
• Another example is a refrigeration system where refrigerant circulates but does not exit the circuit.

Closed systems are important in contexts where the matter needs containment while energy is still utilized or released. Usually, these systems are designed to minimize the exchange with the environment except under controlled conditions.

Isolated System

An isolated system is truly self-contained, with no exchange of either matter or energy with the environment.
This theoretical concept is used to simplify analyses in thermodynamics since absolutely isolated systems are rare in practical terms.

• A perfect thermos flask attempts to achieve isolated conditions by minimizing energy and matter exchange with its surroundings.
• This system serves as a reference point in studies where interactions need to be controlled or eliminated for testing purposes.

Understanding isolated systems helps in setting up theoretical boundaries and offers insights into energy conservation and matter retention.

Adiabatic System

An adiabatic system is a specialized type of closed system that does not allow heat transfer across its boundary.
This means that while the system can do work and internal energy changes can occur, no heat is gained or lost.

• An example is a rapid compression or expansion of gas in an insulated cylinder where temperature rises or falls with volume changes.
• This principle is often applied in processes like the adiabatic engine cycles in thermodynamics.

Adiabatic processes are vital in understanding how systems respond without external heat influences, thus simplifying calculations related to internal energy and work done.