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View Full Version : Proof gas loses 1/273 of its volume - Charle's Law


ghostanime2001
Nov29-11, 07:44 PM
1. The problem statement, all variables and given/known data
Show that any gas loses 1/273 of its volume at 0 °C, when it is cooled by 1 Celsius degree.

V_{1}=?

V_{2}=?

T_{1}=0 °C=273 K

T_{2}=272 K

2. Relevant equations
I'm assuming I have to use Charle's Law AND starting with any starting arbitrary volume:

\dfrac{V_{1}}{T_{1}}=\dfrac{V_{2}}{T_{2}}

3. The attempt at a solution

So substituting in all the values above and solving for V2 I get:

\dfrac{V_{1}}{273}=\dfrac{V_{2}}{272}

272V_{1}=273V_{2}

\dfrac{272}{273}V_{1}=V_{2}

\dfrac{273-1}{273}V_{1}=V_{2}

\left(\dfrac{273}{273}-\dfrac{1}{273}\right)V_{1}=V_{2}

\left(1-\dfrac{1}{273}\right)V_{1}=V_{2}

V_{1}-\dfrac{1}{273}V_{1}=V_{2}

That's as far as I can get and I guess it makes sense? If I start with any V_{1} i subtract that with 1/273th of the initial volume and i get the second volume. Assuming I start with

V_{1}=1 L, the second volume V_{2} would be 0.996 L. The second set of experimental conditions are colder so I expect the volume to decrease following Charle's Law.

BUT! am I supposed to show explicitly that \dfrac{1}{273}=V_{2} ? How do I show \dfrac{1}{273}=V_{2} explicitly?

Borek
Nov30-11, 02:44 AM
You are almost done. Hint: loses 1/273 volume doesn't mean V2=1/273. Try to express the loss in terms of V1-V2, or V2/V1.

technician
Nov30-11, 08:32 AM
Volume is proportional to T in Kelvins.
The volume at 0C (273K) = Vo, the volume at -273C (0K) = 0
Change in volume ???? Change in temp ????

Barakn
Nov30-11, 06:40 PM
the volume at -273C (0K) = 0
Change in volume ???? Change in temp ????
The volume at 0K = 0 only holds for ideal gases (hint: nothing is ideal).

technician
Dec1-11, 12:47 AM
removed

Borek
Dec1-11, 01:59 AM
This discussion if off topic, and in no way helpful for the OP. Question doesn't need any information about gas behavior at 0 deg K to be solved.