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State Property

Posted: Sun Jan 27, 2019 12:45 pm
by 105114680
Can someone please explain what it means for a state property to be independent of the path taken to obtain that state? I understand state properties are only concerned with the current state of a substance, but what does the "path taken" refer to? Would that have to do with heating, cooling, etc.?

Re: State Property

Posted: Sun Jan 27, 2019 1:09 pm
by David S
Imagine if you are to climb up a mountain. Let's say I ask you for the distance you traveled to get to the top, which is 400 meters above the starting point altitude wise. If you follow a trail the distance to the top might be 10 miles. But if you take a bunch of shortcuts, you might get there after 8 miles. If you go to the Moon first then back down to get to the top of the mountain, your distance travelled will be much longer.

The distance travelled is an example of a path dependent property because the path you take determines the distance you travel. On the other hand, no matter what path you take in the situation above, you still will end up only 400m above the starting point. This is why we call altitude a state property, as it's value depends only on your current state (400 meters above starting point), and not what you did to achieve that state (going to the Moon and back to end up 400 meters above the starting point)

Now think about heating a cup of water to 100°C. If I ask you how much heat you put into that cup of glass to get to 100°C, your answer may differ depending on how you heated the cup. If you heated it straight to 100°C, you would have used less heat than if you would heat it to 90°C, let it cool to 70°C, and heat it back up to 100°C. In the end the temperature state is 100°C

Re: State Property

Posted: Sun Jan 27, 2019 1:12 pm
by Jaira_Murphy_2D
A State Property being independent of its path just means that how the system attained that state doesn't matter. For example how fast or slow the change happened doesn't matter, only its actual initial and final state matter. The value only depends on its current state not how it got there.

Re: State Property

Posted: Sun Jan 27, 2019 2:20 pm
by KatrinaPho_2I
I understand state properties as values that are added and subtracted to find simple relationships of position. For example, the positions of two people can be compared. Person #1 is at the 5 meter mark while Person #2 is at the 8 meter mark. It doesn't matter how quickly someone traveled, what path they took, or how they got there, all that matters is that the difference in their final positions is Person #2 is 3 meters further than Person #1.