Difference between Open, Closed and Isolated System – Examples

We explain the difference between an open, closed and isolated system, the relationship of each one with the environment and its characteristics.

What is the difference between an open, closed and isolated system?

To understand the difference between an open system, a closed system, and an isolated system, we must first understand what we mean by “system.” As defined by the dictionary, a system is a set of ordered and interrelated things that contribute to an end.

That is to say, that a system is an organized whole, a notion that applies both to certain sets of body organs, or to the totality of a natural ecosystem, as well as to different phenomena and air temperatures in the atmosphere. Any segment of the universe that we decide to study in itself, ignoring the rest and focusing on its internal relationships, is a system.

This notion is extremely useful in physics, since through a systemic look we can identify the energetic and material phenomena that occur around us.

Thus, it is common to speak of physical systems, such as thermodynamic systems, in which there is an internal flow of matter and energy, which can be more or less linked to the environment. That is to say, a system can be more open or more closed, depending on how much information goes in and out of it. The information that circulates can be for example matter and / or energy.

Thus, we have three main types of physical systems: open, closed, and isolated.

• Open systems. They are those who freely exchange matter and energy with the outside. For example, our bodies themselves are systems in continuous exchange with the environment: oxygen and food enter them, and waste substances, such as CO, are expelled.₂ or ammonia in urine. In addition, we continually lose heat when the environment is colder, and we lose moisture (water vapor) with each breath we take.
• Closed systems. Sare those that freely exchange energy (but not matter) with their environment. This energy can come in the form of heat, light, or work. For example, a light bulb is a closed system in which not a single particle of matter enters or leaves, but electricity enters and light energy is extracted in return.
• Isolated systems. They are those that do not exchange matter or energy with the environment, either because they are very far from any other system or because they have barriers that reduce (or, ideally, impede) the traffic between the inside and the outside. For example, a thermos for hot water is designed to delay as much as possible (prevent it altogether is impossible) the cooling of the liquids inside, thus minimizing the loss of heat from the substance.

We must insist that strictly speaking, there is no totally isolated system in the universe. All systems exchange information to some extent with their environment, although in some cases in negligible amounts or simply in such a way that it can be ignored for the study of the system itself.