Author Topic: gas laws..  (Read 6335 times)

nid404

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gas laws..
« on: September 30, 2009, 07:04:16 am »
1) An iron cylinder contains He at a pressure of  250KPa at 300K. the cylinder can withstand a pressure of 1X10^6 Pa. The room in which the cylinder is placed catches fire. Predict whether the cylinder will blow up before it melts or not.....

2) The density of a gas at 27 degrees celcius and 760mm pressure was found to be 3g/l. Find out the temperature at which the density will become 2.4g/l, keeping pressure constant


Please answer


Thanks :)

« Last Edit: September 30, 2009, 08:56:55 am by nid404 »

nid404

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Re: gas laws..
« Reply #1 on: September 30, 2009, 07:10:04 am »
okay I actually got the second one but want to confirm if it is 375K

Please answer the first one....astar..or adi and slvri
« Last Edit: September 30, 2009, 08:42:26 am by nid404 »

Offline astarmathsandphysics

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Re: gas laws..
« Reply #2 on: September 30, 2009, 07:32:35 am »
In bed. Will answer when i get up.

nid404

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Re: gas laws..
« Reply #3 on: September 30, 2009, 08:09:54 am »
okay....take ur time :D

Offline astarmathsandphysics

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Re: gas laws..
« Reply #4 on: September 30, 2009, 08:48:25 am »
1) An iron cylinder contains He at a pressure of 300K. the cylinder can withstand a pressure of 1X10^6 Pa. The room in which the cylinder is placed catches fire. Predict whether the cylinder will blow up before it melts or not.....

2) The density of a gas at 27 degrees celcius and 760mm pressure was found to be 3g/l. Find out the temperature at which the density will become 2.4g/l, keeping pressure constant

1/ the volume is constant since it is the volume of the room.
\frac {P_1}{T_1}=\frac {P_2}{T_2} so T_2=P_2 \frac{T_1}{P_1}=10^6 *\frac{300}{250000}=1200K
Much more borderline than before, but still I say it wont melt.I think it will not melt since the temp of the fire is typically up to 1000K so the pressure will be less than 10^6

2)P1/d1=P2/d2
temp will be 2.4/3 *300=240K
« Last Edit: September 30, 2009, 02:55:56 pm by astarmathsandphysics »

nid404

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Re: gas laws..
« Reply #5 on: September 30, 2009, 08:56:14 am »
Sorry I made a blunder

I've modified the question

nid404

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Re: gas laws..
« Reply #6 on: September 30, 2009, 02:15:28 pm »
I've modified it...please answer ???

Offline slvri

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Re: gas laws..
« Reply #7 on: September 30, 2009, 02:39:29 pm »
1) An iron cylinder contains He at a pressure of  250KPa at 300K. the cylinder can withstand a pressure of 1X10^6 Pa. The room in which the cylinder is placed catches fire. Predict whether the cylinder will blow up before it melts or not.....

2) The density of a gas at 27 degrees celcius and 760mm pressure was found to be 3g/l. Find out the temperature at which the density will become 2.4g/l, keeping pressure constant


Please answer


Thanks :)


this is physics right..........u guys are already so far ahead? i dont know how to answer this q cuz i aint studied this.........sory :-[
i hate A level...........

Offline astarmathsandphysics

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Re: gas laws..
« Reply #8 on: September 30, 2009, 02:53:40 pm »
I modified my post too.

nid404

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Re: gas laws..
« Reply #9 on: September 30, 2009, 03:10:56 pm »
thanks sir


but shouldn't the second  be  1/T1d1=1/T2d2


considering vapour density :-\

nid404

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Re: gas laws..
« Reply #10 on: September 30, 2009, 03:13:54 pm »
this is physics right..........u guys are already so far ahead? i dont know how to answer this q cuz i aint studied this.........sory :-[

No problem slvri

Offline astarmathsandphysics

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Re: gas laws..
« Reply #11 on: September 30, 2009, 03:16:21 pm »
pV= K but d=m/V soV=M/d so p/d=K

nid404

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Re: gas laws..
« Reply #12 on: September 30, 2009, 03:49:37 pm »
pV= K but d=m/V soV=M/d so p/d=K

In this case the pressure is constant ???

so isn't it

t1d1=t2d2
300KX3=2.4Xt2
t2=375K

I'm confused :-\


Offline astarmathsandphysics

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Re: gas laws..
« Reply #13 on: September 30, 2009, 06:50:15 pm »
it says in the question the pressure is constant

nid404

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Re: gas laws..
« Reply #14 on: October 04, 2009, 12:07:58 pm »
another question

0.23g of a volatile solute displaced 112ml of air at  NTP. Calculate the vapour density and the molecular weight of the substabce