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A closed system in a physical system is a system in which the materials contained in the system are not affected by other external agents.
Thermodynamic systems can be closed or open.
In thermodynamics, a closed system can exchange energy (such as heat or work), but the matter can not be transferred across the boundary.
On the other hand, an open system can exchange matter and energy. For example, in a hydroelectric power station, there is an exchange of energy and matter.
Closed systems are sometimes confused with isolated systems. In both cases, energy transfer is possible. However, an isolated system cannot exchange heat, work, or matter with the environment, while a closed system can.
In the case of an adiabatic process in a closed system, even if heat and mass are not transferred, it can do work.
A thermodynamically closed system can be imagined as an airtight container. It is a system whose walls are heat conductive and can be deformable; that is, its volume can vary. If the volume changes without mass exchange, it means that its content has a specific volume constant.
A closed system passes through an infinite number of intermediate states. The temperature and pressure gradients in the system are negligibly small. This is called a quasi-equilibrium process.
The relationship between heat and temperature when the heat is added to a system is the specific heat. Specific heat is the amount of energy that must be added, in the form of heat, to one unit of mass of the substance in order to cause an increase of one unit in temperature.
Frequently considered cases of closed systems are closed isothermal systems at constant pressure.
Examples of Closed Systems
To better understand the concept of this type of system, we list some examples:
Earth is considered a closed system. Heat is added to the Earth as it receives solar energy, while the total mass remains constant, with (almost) no exchange from space.
A pressure cooker that does not allow gas to escape experiences a change in energy but not the mass. The food we cook receives heat energy, but its mass does not vary.
A Stirling engine exchanges energy with the outside without changing its mass. This type of motor receives external thermal energy and supplies mechanical energy. In this case, the work done by the system is positive.
A solar thermal system captures energy from the Sun and provides thermal energy to another system. However, the total mass remains constant.
The piston-cylinder arrangement in an internal combustion engine is only a closed system during the compression stroke and the power stroke. In the case studies, the piston-cylinder system is approximated by an ideal gas or an atomic gas.
Laws of Thermodynamics in Closed Systems
According to the first law of thermodynamics for these systems, the change in internal energy is equal to the added work and heat. During an interaction between a system and its surroundings, the amount of energy gained by the system must be precisely equal to the amount of energy lost by the surroundings.
According to the second law of thermodynamics, the closed system's entropy increases with the heat absorbed and the work dissipated.
In this type of system, the conservation of masses of classical physics can also be applied, in which the mass remains constant.
In relativistic physics, however, the decrease in the system's energy content automatically reduces the system's mass.
Author: Oriol Planas - Industrial Technical Engineer, specialty in mechanics
Published: February 26, 2021
Last review: February 26, 2021
Teach AP® chemistry with confidence and ease
A system refers to any parts of the universe being studied.
If you are conducting an experiment in a beaker, then the system you are studying is in the beaker.
The system is subject to surrounding factors such as air temperature and pressure.
Thermodynamics involve the study of heat energy exchange between a system and its surroundings.
There are three types of thermodynamics systems. Based on the possible heat and matter transfer, they are classified as open, closed or isolated systems.
Types of Thermodynamic Systems
Open Systems
You may have heard of open systems and closed systems. An open system is one that freely allows both energy and matter to be transferred in an out of a system.
For example, boiling water without a lid.
Heat escaping into the air.
Steam (which is matter) escaping into the air.
Closed Systems
A closed system, on the other hand, does not allow the exchange of matter but allows energy to be transferred.
It allows heat to be transferred from the stove to the water
Heat is also transferred to the surroundings
Steam is not allowed to escape
Example of a closed system – a pressure cooker.
Nb: If a system is 100% closed, it is in danger of exploding. That's why a pressure cooker should be designed with safety mechanisms to prevent the system from over-pressurzing by allowing steam to escape when needed.Isolated Systems
This system is completely sealed. Neither matter nor heat can transfer to or from the surroundings.
By Areej Z. October 26, 2021
In order to study thermodynamics, the universe is divided into two parts, the system, and the surrounding. The part of the universe under observation is called the system and all things in the universe except the system are called surroundings. It is a region where measurements are made relative to the system.
For example, if we are performing an experiment in the lab, a beaker, flask, or burette in which a reaction is occurring is called a system, while all other things in the lab are the surrounding.
The system may be a reaction vessel, an engine, an electrochemical cell, and a biological cell, etc. The real or imaginary surface that separates the system and surroundings is called boundary. The type of system depends on the characteristics of the boundary that divides it from the surrounding.
Types of the systems
1. Open system
The system which can exchange both matter and energy with surroundings is called an open system. They are a portion and in intimate contact with the larger system. Open systems are sometimes termed flow systems, because of the ability to exchange mass of a substance.
Examples of an open system
- Human body.
- An automobile engine.
- A beaker of water, where water can evaporate and the beaker does not insulate inside at all.
All real systems are open systems.
2. Closed system
The system which can exchange only energy with surroundings is called a closed system. Matter cannot be exchanged in a closed system. Closed systems are not usually portions of larger systems and are not even in complete contact with them. Closed systems are sometimes also called non-flow processes, because of the inability to exchange mass of a substance, over a procedure.
Examples of a closed system
- The earth is a closed system. It receives lots of energy from the sun but the exchange of matter with the outside is not possible.
- Covered beaker of water. It is a closed system because only heat energy can leave or enter, the amount of matter (water) will always remain the same unless disturbed.
- Putting an ice bag on an injury with some bag or plastic to contain water from entering, if there is a wound.
Closed systems are not real. They are imaginary systems.
3. Isolated system
The system in which neither energy nor matter can be exchanged with surroundings is called an isolated system. An isolated system may be a portion of larger systems, but they do not communicate with outside in any way.
Examples of an isolated system
- The physical universe is an isolated system.
- Combustion of glucose in a bomb calorimeter is an isolated system unless some real parameters take place.
- A closed thermos bottle or a sealed vacuum flask is essentially an isolated system if the real exceptions are avoided.
Transfer of heat energy in the system
Heat can be transferred between open systems and between closed systems but for isolated systems, it is not an option to transfer heat or energy.
Related Topics
Concepts berg
What is a closed system?
The system that allows only the transfer of energy in or out of the system but does not allow the transfer of matter is known to be a closed system.
For example, a beaker of evaporating water with a closed lid on it allows the transfer of energy to the surroundings but does not allow (matter) water to leave.
What is one example of a closed system on earth?
An example of a closed system on the earth is a cup of tea with a lid on it. The only transfer of energy takes place with the surrounding, not the tea. Other examples are, simple water bottle or closed frying pan, etc.
What is an example of a closed system in chemistry?
An example of a closed system in chemistry is the pressure cooker covered with a lid, a beaker of evaporating water with a lid on it, and putting an ice pack on an injury.
What is an example of a closed system in business?
In a business closed system, there is no exchange or receiving of information with any outside system. It has no interaction with the outer environment and contains information within the system. Business closed systems are quite similar to chemically closed systems.
Is an egg a closed system?
A fertilized hen’s egg is an example of an open system. It is not a closed system. In this case, the shell and chick embryo is a system while the nest and hen are the surroundings. Oxygen and carbon dioxide are exchanged between the system and surroundings which is necessary to sustain embryo metabolism.
Is Earth an open or closed system?
Earth is a closed system because it allows only the exchange of energy but does not allow the exchange of matter. It receives the energy from the sun and radiates it back to space. This is a natural process.
What are real-life examples of closed-loop systems?
Some real-life examples of closed systems are.
- Human body
- Thermostat
- Air conditioner
- Steering of car
- Electric iron etc.
What are some examples of open systems?
An open system allows both the transfer of matter and energy between the system and its surroundings. Some examples of open systems are.
- An open beaker of evaporating water
- A cup of tea
- An open frying pan
- An open soda can etc.
Is the universe an open or a closed system?
The universe is neither an open system, closed system nor an isolated system. The observed universe in which we can observe all things is an open system because it can exchange both matter and energy with the boundary that we cant see. The entire universe seems to be an isolated system because there is no other boundary to transfer energy or matter.
What is the difference between a closed system and an open system in thermodynamics?
The system which allows the transfer of energy and matter with the surrounding is called an open system. For example, an open bowl of hot soup, etc.
The system which allows only the transfer of energy but does not allow the exchange of matter with the surrounding is called a closed system. For example, a covered bowl of hot soap, etc.
What is a steady-state in thermodynamics?
The process in which the properties of the system are independent of time is called a steady-state. In this condition, the variables of the system such as mass and energy remain unchanged as the procedure goes on.
What is a non-flow process?
It is a process in which no mass transfer takes place between the system and surroundings. Examples of the non-flow process are the isochoric (constant volume) process, isobaric (constant pressure) process, and isothermal (constant temperature) process.
What is the difference between a flow and a non-flow process?
The flow process occurs in an open system in which mass interaction is possible between the system and surroundings. For example, water is flowing in and out of the pipe, etc.
The non-flow process occurs in a closed system in which no interaction of mass is possible with the surrounding. For example, a cup of tea with a lid on it, etc.