Isolated vs. Closed System

[Rachel Chan 1B]

Just to clarify, isolated systems are isolated because there is some sort of material/buffer (like a foam cup) to absorb the heat, whereas closed systems don't have this material/buffer to absorb the heat, so the heat just gets taken up by the surroundings? Furthermore, does the cup not count as surroundings? Is the cup part of the system?

[Celine_Nguyen_3K]

From what I understand, a closed system allows energy to be exchanged with its surroundings while preventing matter from being exchanged, whereas an isolated system doesn't allow energy nor matter from entering or leaving the system. So, your reasoning about the presence of a buffer does logically make sense. In this case, since the definition of an isolated system means that matter and energy cannot enter nor leave, it would be reasonable to assume that the cup acts as part of the system rather than the surroundings.

[Alan Nguyen 2I]

The difference between the two is that isolated systems do not allow for a transfer of energy, while closed systems do. This usually entails some sort of insulant between the surroundings and the system in an isolated system, to prevent this transfer of energy.

[Hannah Chang 1F]

Just as other students have mentioned, isolated systems and closed systems both do not allow matter to flow in and out of the system. Isolated systems, however, have an extra characteristic in that they do not allow the exchange of energy between the system and environment. More specifically, energy in the form of "heat" cannot be exchanged between the system and environment for an isolated system. The only way an isolated system can lose/gain energy is if that energy is in the form of work (this has to do with the 1st law of thermodynamics, which is delta U = Q + W... some textbooks/online sources write the equation as delta U = Q - W though, so it just depends on how positive/negative work is defined by the textbook/online source). If Q, which is the heat transfer of a system, equals 0 in an isolated system, then that means that the change in internal energy of an isolated system can only be due to work being done on or by the system (delta U = W).

[Amy Jordan 2A]

Hi, yes, in an isolated system there is no energy exchange with the surroundings (ex. an insulated beaker), while in a closed system energy can exchange with the surroundings (ex. a sealed beaker.) In your example I think the insulation would be part of the system and not the surroundings, but I think that questions would usually make the distinction? Hope this helps!