# What is the Difference Between Isolated System and Closed System

The main difference between isolated system and closed system is that isolated systems do not allow any exchange, maintaining a constant total energy and matter, while closed systems permit the exchange of energy but not matter across their boundaries.

In thermodynamics, a system refers to a specific portion of the universe that is under consideration. It can be an object, substance, or region chosen for analysis, and it is separated from the rest of the universe by boundaries. The interactions between a system and its surroundings, including the exchange of energy and matter, form the basis for studying the thermodynamic properties and behaviors of different systems.

### Key Areas Covered

1. What is an Isolated System
– Definition, Features, Uses
2. What is a Closed System
– Definition, Features, Uses
3. Similarities Between Isolated System and Closed System
– Outline of Common Features
4. Difference Between Isolated System and Closed System
– Comparison of Key Differences
5. FAQ: Isolated System and Closed System

### Key Terms

Isolated System, Closed System

## What is an Isolated System

An isolated system is a theoretical or practical system that does not exchange energy or matter with its surroundings. This means that an isolated system is characterized by the absence of any transfer of heat, work, or mass across its boundaries. The concept is crucial in understanding and applying the laws of thermodynamics, which govern the behavior of energy and matter in various physical systems.

The defining feature of an isolated system is its strict conservation of energy. No energy enters or leaves the system. This implies that the total energy content of the isolated system remains constant over time. Energy can exist in various forms within the system, such as kinetic energy, potential energy, and internal energy, but the sum of these remains unchanged. In addition to energy conservation, an isolated system does not exchange matter with its surroundings. The quantity of matter within the system remains constant. In fact, this characteristic distinguishes an isolated system from other types of systems where matter exchange is possible.

The boundaries of an isolated system are typically considered impermeable to both energy and matter. This means that heat, work, and mass cannot pass through the system’s boundaries. Entropy is a thermodynamic property related to the disorder or randomness of a system. In an isolated system, the total entropy remains constant or increases over time, in accordance with the second law of thermodynamics. This reflects the tendency of natural processes to move towards greater disorder.

While the concept of an isolated system is valuable for theoretical discussions, achieving perfect isolation in practice is challenging due to factors such as thermal conductivity, imperfections in physical barriers, and the influence of external fields.

## What  is a Closed System

In a closed system, the total mass of the system remains constant over time. This means that while energy can flow into or out of the system, the actual substance or matter within the system remains unchanged. The closed system concept is often used as a simplification in scientific and engineering analyses to focus on energy interactions without considering the complexities of matter exchange.

A closed system can be thought of as a well-defined boundary that separates it from its surroundings. This boundary allows for the exchange of energy, usually in the form of heat or work, but it restricts the transfer of mass. The closed system assumption is valid for many practical situations, such as a container with fixed walls that allows only heat to be exchanged with the surroundings.

Understanding closed systems is crucial in the study of thermodynamics, which provides a framework for analyzing and predicting the behavior of physical systems. The first law of thermodynamics, also known as the law of energy conservation, states that the total energy of an isolated system is constant. For a closed system, this law implies that the internal energy of the system can change due to the exchange of heat or work, but the total energy is conserved.

Mathematically, the first law of thermodynamics can be expressed as:

ΔU=Q−W

where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done by the system. In a closed system, the mass remains constant, so the focus is on energy changes.

### Examples of Closed Systems

Closed systems play a crucial role in various scientific and engineering applications. Understanding and analyzing closed systems are fundamental to the design and operation of many devices and processes. Here are a few examples:

• The operation of heat engines, such as car engines or steam engines, involves closed systems. The working fluid (usually a gas) undergoes a thermodynamic cycle within a closed system, converting heat energy into mechanical work.
• Refrigerators and air conditioners also operate within closed systems. These systems transfer heat from a low-temperature region (the inside of the refrigerator) to a high-temperature region (the surroundings) using a closed loop of refrigerant.
• In chemical engineering, closed systems are often used to model reactions where the total mass of the reactants and products remains constant. While energy may be exchanged, the overall composition of the system remains unchanged.

## Similarities Between Isolated System and Closed System

• Both isolated and closed systems adhere to the principle of conservation of energy.
• The conservation of energy in both isolated and closed systems can be expressed using similar mathematical equations.

## Difference Between Isolated System and Closed System

### Definition

An isolated system is a theoretical or practical system that does not exchange energy or matter with its surroundings,  while a closed system is a system that does not exchange matter with its surroundings but allows the transfer of energy across its boundaries.

### Energy

No energy or matter can enter or exit an isolated system as it is thermally and mechanically isolated. While matter cannot enter or exit in a closed system, energy transfer, especially in the form of heat and work, is possible.

### Nature

Perfectly isolated systems are idealized concepts used for theoretical discussions, while closed systems are more practical and easier to approximate in real-world situations.

### Examples

While truly isolated systems are theoretical constructs, examples are challenging to find in the real world. A sealed container with fixed boundaries that allows heat transfer but restricts the exchange of matter is an example of a closed system.

## FAQ: Isolated System and Closed System

### Is Earth a closed or isolated system?

Earth is considered a closed system because only energy is naturally transferred outside the atmosphere. While matter requires a violation of physical laws to leave Earth’s atmosphere, external matter, such as meteorites, is prevented from entering.

### What is the difference between an isolating boundary and a closed boundary?

An isolating boundary prevents both matter and energy transfer, while a closed boundary allows for energy transfer but not matter transfer.

### Is the sun an open or closed system?

The Sun is an open system. It continuously releases energy in the form of light and solar wind into space. While it does not exchange matter with its immediate surroundings, it allows the transfer of energy across its boundaries.

## Conclusion

An isolated system restricts both matter and energy transfer, maintaining a high degree of independence. On the other hand, a closed system permits energy exchange but not matter exchange. Thus, this is the main difference between isolated system and closed system.

##### Reference:

1. “Isolated System.” Wikipedia. Wikipedia Foundation.
2. “Closed System.” Wikipedia. Wikipedia Foundation.

##### Image Courtesy:

1. “Diagram Systems” By Grasso Luigi – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Work of Closed System” By Shoji Yamauchi – Own work (CC BY-SA 4.0) via Commons Wikimedia

### About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.