CHEMISTRY COMMUNITY

How can you change the energy in a closed system? And does it differ with isolated systems?

Emily Lo 1J wrote:How can you change the energy in a closed system? And does it differ with isolated systems?

Quoting this because I want to see the replies that it gets :)

In a closed system, you can change the energy by adding heat and/or doing work on the system. I am less certain with the isolated system, but I am pretty sure there should be no net change in the total energy of the system.

On a closed system, you can add energy by adding it to the entire system, which is different from an open system where you can pick where to add work/energy, or an isolated system where you can't add energy, I think.

In a closed system, pressure can be applied.

In a closed system, energy can be exchanged with surroundings, unlike an isolated system in which nothing can be exchanged with the surroundings. The energy of a closed system can be changed by heating/cooling or compression/expansion (i.e. compressing a piston).

ΔU = q + w, so to change the energy of a closed system, you would heat it or do work on it.

KBELTRAMI_1E wrote:

Emily Lo 1J wrote:How can you change the energy in a closed system? And does it differ with isolated systems?

Quoting this because I want to see the replies that it gets :)

I would assume you would add heat to change energy since the system is isolated.

An example of changing energy of a closed system would be adding or removing heat, or compression/expansion. An isolated system cannot transfer energy with its environment.

Heat transfer can occur in a closed system or work can be done via compression/expansion. We cannot add any substance in the system, but heat transfer can occur between the system and surroundings. Think of a cold ice pack as a closed system.

in a closed system, you can change the energy by doing work/having work done on the system or by changing the temperature

deltaU = q + w so you can change it by adding heat or doing work

Eva Zhao 4I wrote:In a closed system, energy can be exchanged with surroundings, unlike an isolated system in which nothing can be exchanged with the surroundings. The energy of a closed system can be changed by heating/cooling or compression/expansion (i.e. compressing a piston).

very helpful!

A closed system means that the system is closed off from exchanging mass with its surroundings but it can exchange energy. An isolated system cannot exchange either. Energy can be introduced into a closed system either through heat or work (increasing pressure).

In a closed system, energy can be exchanged in and out of the system, but matter can't. So by adding or removing heat, you can change the energy in the system. In an isolated system, nothing can be exchanged and there isn't a way to change the energy within the system.