Open, Closed, or Isolated Systems

[Susan Lei]

What are the differences between an open, closed, or isolated system? What kind of system is hot chocolate in a thermos bottle?

[Kim Vu 2G]

open system is when energy and matter of the system is exchanged with the surroundings. A closed system is when there is a fixed amount of matter in the system but still can exchange energy with its surrounding and an isolated system is when the system has no contact or exchange with its surrounding. Because the hot chocolate is being closed off from its surrounding by the thermo bottle and there is no exchange in neither energy nor matter, the system is isolated.

[Joyce Xiong 4C]

Hey Susan!

So in thermochemistry, heat is exchanged between the system and its surroundings. The system is what you would be studying (an organism, a beaker) and the surrounding is the external environment that this system interacts with (the environment the organism is at, a lab where the beaker is located).

An open system is one in which the system and surroundings freely interacts with one another. An example is a pot of boiling water that does not have a lid on it. In this case, both energy and matter is being transferred with that of the surrounding, say the kitchen. Energy in the from of heat is being transferred from the pot to the kitchen atmosphere, and matter, water in this case, is leaving the pot and into the kitchen in the form of steam. When both energy and matter can be exchanged between the system and surrounding, the system is called an open system. On the other hand, an isolated system is a system where both heat and energy is not exchangeable with its surroundings. The example you gave about a thermo-bottle would be an isolated system. In between, there is what is called a closed system, where energy can be transferred, but not matter. So if you put a lid on the pot, heat is still going from the hot to the atmosphere of the kitchen, but water within the pot, is securing under the lid, and not allowed to be transferred out.

Hope this helps!

[Helen Shi 1J]

Can someone explain exercise 8.1 part e? Why would mercury in a thermometer be a closed system rather than isolated?

[Sally Nason - 1K]

It would be a closed system because while the mercury cannot leave the thermometer, heat can be transferred to or from the thermometer, therefore not making it isolated.

[Jessica Nunez 1I]

To add on, an isolated system has no contact with surroundings. However, in the case of the thermometer, the heat of the mercury can be transferred to or from the thermometer.

[404995677]

Also thermometers work because the liquid (mercury) expand or compress depending on the heat transfer between the mercury and the surrounding, so it is a closed system