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Why is coffee in a thermos bottle considered an isolated system? Why is it not closed? From personal experience the coffee in my thermos bottles would eventually cool down within an hour or so--doesn't that mean energy is being exchanged with the surroundings?
The question calls it a "very high quality" thermos bottle, so I think that it wants you to assume that the coffee is perfectly insulated. Therefore, no heat would be transferred in or out, making it an isolated system. Hope this helps!
A bomb calorimeter would be considered an isolated system because the system is closed off to the external environment, being incased within the exterior, insulating walls. Therefore, there is no transfer of heat to the outside surroundings; thus, it is an isolated system.
In reality, we know that over time, heat will be lost in a thermos bottle, so it practically a closed system. In theory, however, an insulated thermos bottle is an isolated system because neither mass nor energy is exchanged with its surroundings.
Coffee in a thermos bottle would not exchange heat with it's surroundings because a thermos bottle is an isolated system. Therefore, it cannot exchange energy or matter with it's surroundings. However, the amount of time the temperature of the coffee remains hot can really depend on the type of thermos bottle you are using.
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