Why can state properties be added?

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Jack Papciak 2F
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Joined: Fri Sep 29, 2017 7:06 am

Why can state properties be added?

Postby Jack Papciak 2F » Wed Jan 10, 2018 6:35 pm

I understand the definition of state properties but I am a little confused as to why they can be added and subtracted. Any help would be greatly appreciated!

JamesAntonios 1E
Posts: 70
Joined: Fri Sep 29, 2017 7:04 am

Re: Why can state properties be added?

Postby JamesAntonios 1E » Wed Jan 10, 2018 6:46 pm

They cannot be changed by intrinsically. That allows for them to be added. For example, work cannot be added together because of how "it is prepared." Either force or distance can be changed. But energy "preparation" is the same, and likewise for all state properties, allowing them to be added.

Harjas Sabharwal 1G
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Joined: Sat Jul 22, 2017 3:01 am

Re: Why can state properties be added?

Postby Harjas Sabharwal 1G » Wed Jan 10, 2018 7:22 pm

State properties are pathway independent. Meaning regardless of how the final product is achieved it will always have that particular value (in this case enthalpy).
For example, if you wanted to make a NO2. The enthalpy of NO2 will always be the same, regardless of how it was formed.
Hence, we can add state properties because the sum will end up equaling the product. If it doesn't, then the product is not made.

Kayla Danesh 1F
Posts: 38
Joined: Thu Jul 13, 2017 3:00 am

Re: Why can state properties be added?

Postby Kayla Danesh 1F » Fri Jan 12, 2018 4:37 pm

When it comes to state properties, the path taken to get from point A to point B does not matter. The link: https://chem.libretexts.org/Core/Physic ... _Functions gave an example that really helped me understand this concept better. Here is one of the parts of the article that helped me a lot:

"State functions do not depend on the path taken. Suppose you have $1000 in your savings account. You withdraw $500 from your savings account. It does not matter whether you withdraw the $500 in one shot or whether you do so at a rate of $50. At the end when you receive your monthly statement, you will notice a net withdrawal of $500 and will see your resulting balance as $500. Thus, the bank balance is a state function because it does not depend on the path or way taken to withdraw or deposit money. In the end whether you do so in one lump or in multiple transactions, your bank balance will stay the same."

Irma Ramos 2I
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Joined: Fri Sep 29, 2017 7:07 am

Re: Why can state properties be added?

Postby Irma Ramos 2I » Sat Jan 13, 2018 6:14 pm

As mentioned above, because state properties don't rely on the path taken to get to their state they can be added and subtracted. They are independent in other words so adding and subtracting them is allowed.

Kevin Tabibian 1A
Posts: 42
Joined: Fri Sep 29, 2017 7:06 am

Re: Why can state properties be added?

Postby Kevin Tabibian 1A » Sat Jan 13, 2018 6:22 pm

Think about the example Professor gave in class with altitude. Altitude can be measured using a difference of distances, ie subtraction. You can also get altitudes, a state function, by adding two smaller altitudes. Try not to overthink it

zanekoch1A
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Joined: Thu Jul 13, 2017 3:00 am

Re: Why can state properties be added?

Postby zanekoch1A » Sat Jan 13, 2018 10:39 pm

Maybe the most basic example of the difference between a state property and one that is not is the difference between displacement and distance. Displacement is a state property because if you look at the beginning and ending point that tells you everything you need to know displacement however for distance if you look at the beginning and ending points you cannot calculate distance traveled (because and object could have moved past its ending point and then back making distance not equal to displacement). For this reason, if you're given an objects starting point and the distance it traveled, you cannot determine how far it ended up from the start because the distance could be in any direction. Oppositely, if you're given the amount an object is displaced from its original position you can tell how far it is. So adding up non-state properties like distance do not necessarily tell you accurate information about something but adding state properties do. This is why state properties like enthalpy can be added confidently and without error.

Michelle Lu 1F
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Been upvoted: 1 time

Re: Why can state properties be added?

Postby Michelle Lu 1F » Sun Jan 14, 2018 1:33 am

These state properties are independent of the path taken to transform into their state, allowing these set values to be both added and subtracted.

Caroline LaPlaca
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Joined: Sat Jul 22, 2017 3:01 am

Re: Why can state properties be added?

Postby Caroline LaPlaca » Sun Jan 14, 2018 8:17 am

Due to the fact that they are not based on the state of the substance, they are not an intrinsic property. Therefore, they can be added and substracted.

Kayla Tchorz-Dis 1F
Posts: 30
Joined: Thu Jul 13, 2017 3:00 am

Re: Why can state properties be added?

Postby Kayla Tchorz-Dis 1F » Sun Jan 14, 2018 12:06 pm

As stated before, state properties do not depend on the path taken, and therefore because they’re independent of this, we can add them together.

Mitch Walters
Posts: 45
Joined: Fri Sep 29, 2017 7:07 am

Re: Why can state properties be added?

Postby Mitch Walters » Sun Jan 14, 2018 2:06 pm

State properties can be added because only specific points matter when looking at the states. The paths that are taken don't matter, so we can add the relevant points and forget the rest.

204932558
Posts: 23
Joined: Fri Sep 29, 2017 7:05 am

Re: Why can state properties be added?

Postby 204932558 » Sun Jan 14, 2018 2:31 pm

Being a state property means its value is always the same under certain conditions, no matter how the value is obtained.


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