Integral Calculations


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Integral Calculations

Postby Jeremy_Guiman2E » Sun Feb 02, 2020 10:11 pm

I think we use the integral when we're trying to sum an infinite number of steps (in volume changes?), but can someone explain when to use it and how/why we need to?

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Re: Integral Calculations

Postby peteryim » Sun Feb 02, 2020 10:13 pm

You're right, integrals are used to quickly find the sum of an infinite number of sums. I don't think Lavelle has given us any problems that require us to use it yet...

Ashley Fang 2G
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Re: Integral Calculations

Postby Ashley Fang 2G » Mon Feb 03, 2020 10:26 am

You use the integral in a pressure vs volume graph to find the work of expansion
Since W=-PdeltaV, calculating the integral would give the area under the line (W)

For irreversible expansions, just calculating the rectangular area would be enough
But for reversible expansions, you have to use the integral to find the total area under the line

See Dr. Lavelle's attachments! ... ansion.pdf ... ansion.pdf

Brian Tangsombatvisit 1C
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Re: Integral Calculations

Postby Brian Tangsombatvisit 1C » Mon Feb 03, 2020 10:28 am

For reversible expansion, if we know the number of moles, temperature, and final/initial volume of the sample, we can just use the simplified version of the integral, which is w = -nRTln(V2/V1) instead of integrating. If we were to integrate, I believe we would need a function for pressure with volume as its input variable.

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