gas laws..

[astarmathsandphysics]

one more please
A balloon filled with helium rises to a certain height at which it gets fully inflated to a volume of 100000 litres. If at this altittude the pressure is 0.02 atm and temp is 268K, what weight of helium is required to fully inflate the balloon

when i used PV=nRT i don't get the right answer

Ans-36.36g

n=pV/RT=(0.02*10^5*100)/(8.31*268)=89.8 mols
i mole of helium weighs 4g so 89.8 mols weighs 4*89.8=359.2g

[Ghost Of Highbury]

answer - 36
astar's answer = 359.2 ]

??

misprint?

[astarmathsandphysics]

I checked it too. I still get the same. what did you get?

[Ghost Of Highbury]

lol..i cannot solve an A/AS level physics question.  Only maths questions (most of them)

the answer says - 36g

[astarmathsandphysics]

thin k there may be a factor of 10 too much somewhere.

[Ghost Of Highbury]

okay.

[nid404]

please try....i got the same answer...what's the matter with this question?? r we using the wrong method?

[nid404]

I need help with one more question...

Actually i don't know the formulae for finding out partial pressure...wet and dry gas and stuff....cuz i joined classes late

1) Oxygen is collected over water at 20 degrees Celsius . The pressure inside is shown by the gas is 740mm of Hg. What is the pressure of O2 alone if V.P of H2O is 18mm at 20 degrees celsius

do u simply do 740mm-18mm?? Please help

[astarmathsandphysics]

Exactly

[@d!_†oX!©]

pV= K but d=m/V soV=M/d so p/d=K

ummmm.....i dont really know i need this or not in my exams bt just for my curiosity....cud u plsss expand how u got dese....i understood d first 3.....bt how d last one??
Thanks in advance....By the way is this A levels???

[nid404]

Exactly

THanks a  lot astar U rock!!

[astarmathsandphysics]

pV= K

d=m/V so dV=m so V=m/d so pm/d =K so p/d=K/m =C another constant.
Not the mass m of the gass is fixed so now pressure/density=constant

[nid404]

ok few more please

For 10 min each, at 27 degrees celsius,from 2 identical holes,nitrogen and an unknown gas are leaked into a common vessel of 3 litre capacity. The resulting pressure is 4.18 bar and mixture contains 0.4 mole of nitrogen. WHat is the  molar mass of the unknown gas?

[@d!_†oX!©]

pV= K

d=m/V so dV=m so V=m/d so pm/d =K so p/d=K/m =C another constant.
Not the mass m of the gass is fixed so now pressure/density=constant

ohhkkk......Thanks astar......By the way is this a levels or igcse??this wont come in my exam rite?

[nid404]

ohhkkk......Thanks astar......By the way is this a levels or igcse??this wont come in my exam rite?

nope it won't....it's an iit question....don't worry