PΔV for solids and liquids

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Philip Lee 1L
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Joined: Fri Sep 28, 2018 12:21 am

PΔV for solids and liquids

Postby Philip Lee 1L » Fri Feb 01, 2019 11:25 pm

In lecture today, Dr. Lavelle explained that PΔV is negligible for reactions that involve solids and liquids at constant pressure. However, the book states the following:

"The expression w = -PexΔV applies to all systems. A gas is easiest to visualize, but the expression also applies to an expanding liquid or solid" (7th edition pg. 246)"

From the text, it seems like PΔV is important for solid and liquid reactions as well. Can someone help me clarify this concept?

Chloe Qiao 4C
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Re: PΔV for solids and liquids

Postby Chloe Qiao 4C » Sat Feb 02, 2019 10:15 am

I think what Dr. Lavelle meant is that the equation can also be applied to liquids and solids, but the change is too small that we typically do not consider them.

Aarti K Jain 1L
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Re: PΔV for solids and liquids

Postby Aarti K Jain 1L » Sat Feb 02, 2019 12:11 pm

Also, I assume that his focus on gases means that we won't need to focus on how the expression applies to liquids and solids for tests and such.

ran2000
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Re: PΔV for solids and liquids

Postby ran2000 » Sat Feb 02, 2019 10:46 pm

This equation does apply to every system. However, when we consider solids and liquids, change in volume is essentially 0 (Dr. Lavelle described this in lecture). Hence P(V final- V initial) is 0 and does not affect systems with solid and liquids.

KatelinTanjuaquio 1L
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Re: PΔV for solids and liquids

Postby KatelinTanjuaquio 1L » Sat Feb 02, 2019 10:51 pm

As others have stated, this equation applies to all phases but the change in liquids and solids are so small that the value is essentially 0.

Tuong Nguyen 2I
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Re: PΔV for solids and liquids

Postby Tuong Nguyen 2I » Sun Feb 03, 2019 2:51 am

You could also think of solids and liquids as not having much volume change at all, which in result allows us to make the estimation saying that delta V for a solid or liquid is essentially zero.


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