August 11, 2020, 12:07:10 AM
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Topic: Contradiction in pressure laws  (Read 330 times)

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Offline Speedystar777

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Contradiction in pressure laws
« on: June 05, 2020, 11:03:43 PM »
I was trying to prove the combined gas law to myself, but ended up with an equation that contradicts Boyle’s Law. What logical fallacies did I make?
« Last Edit: June 06, 2020, 04:13:46 AM by Borek »

Offline Meter

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Re: Contradiction in pressure laws
« Reply #1 on: June 06, 2020, 08:33:45 AM »
Your algebra is obviously correct. Your problem is in your interpretation of the laws. Remember what each law assumes as an initial condition and how that differs between the laws.

Offline Babcock_Hall

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Re: Contradiction in pressure laws
« Reply #2 on: June 06, 2020, 09:29:27 AM »
I think learning by doing one's own derivations is a fine way to proceed, and making mistakes is an important part of the learning process.

Offline MNIO

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Re: Contradiction in pressure laws
« Reply #3 on: June 07, 2020, 02:01:27 PM »
try it like this... we're starting with V1 at constant T and n... and converting it to V'
.. P1V1 = P2V'

then if you start with V' at T1 and P1 and convert it to V2 at constant P and n
.. V' / T1 = V2 / T2

subbing
.. P1V1 = P2 * (T1 * V2 / T2)

you get to rearrange
« Last Edit: June 07, 2020, 05:38:25 PM by MNIO »

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