jkn1121 Posted August 30, 2010 Share Posted August 30, 2010 A man used a hydrogen-filled balloon to fly from Paris 25km into the French side. What’s the mass density of hydrogen relative to air at the same temperature/pressure? What mass of payload can be lifted by 10kg of hydrogen, neglect the mass of the balloon? Link to comment Share on other sites More sharing options...
swansont Posted August 30, 2010 Share Posted August 30, 2010 What work have you done on the problem? Link to comment Share on other sites More sharing options...
Mr Skeptic Posted August 31, 2010 Share Posted August 31, 2010 Also you'll need extra data (find it online) to compare to air density. What will be the volume of your hydrogen at, say, standard temperature and pressure? Link to comment Share on other sites More sharing options...
jkn1121 Posted August 31, 2010 Author Share Posted August 31, 2010 Standard Stage: Vol= 24.8 dm^3 Pressure: 1 atm I'm not sure where to start or formula to use, not sure if the formula PV=nRT? Link to comment Share on other sites More sharing options...
swansont Posted August 31, 2010 Share Posted August 31, 2010 Standard Stage: Vol= 24.8 dm^3 Pressure: 1 atm I'm not sure where to start or formula to use, not sure if the formula PV=nRT? PV=nRT is a good place to start Link to comment Share on other sites More sharing options...
Mr Skeptic Posted August 31, 2010 Share Posted August 31, 2010 I'm not sure where to start or formula to use, not sure if the formula PV=nRT? Yes, that is a very useful formula. n you can calculate for a given mass of sample, R is a constant. So long as you're dealing with ideal gases (which should be the case here), then the effects of P and T will be the same for both gas samples, so that they will cancel out. Link to comment Share on other sites More sharing options...
jkn1121 Posted August 31, 2010 Author Share Posted August 31, 2010 If P and T cancels out, so R is given and V is 24.8 dm^3, I calculate for n PV= nRT V= nR n= V/R n= 24.8/.0826 = 302.21mol * 4g/mol = 1208g Link to comment Share on other sites More sharing options...
swansont Posted August 31, 2010 Share Posted August 31, 2010 4g/mol? Link to comment Share on other sites More sharing options...
jkn1121 Posted August 31, 2010 Author Share Posted August 31, 2010 oh crap i take He g/mol instead of H2, so the answer is 302.21g Link to comment Share on other sites More sharing options...
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