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AphroditeIncubus
Probably a bot.
Joined: 16 Nov 2005
Posts: 1
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 Posted: Wed Nov 16, 2005 10:36 pm Post subject: In serious need of help |
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I need some serious help.. I have a gas law problem set and I can't figure out how to do some problems (my brain is fried) Could anyone help out? Any type of information will be most appreciated.
1) O2 has density of 1.43 g/L at STP. What will be the mass of 600.0 mL of O2 at 22.4 C and 742.5 mm Hg?
2)Chlorine diffuses 2.24 times faster than gas Q. What is the MW of gas Q?
3)Compute the volume in mL of 5.30 g CO2 at STP.
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chemistrygosu
Junior Member
Joined: 17 Feb 2006
Posts: 5
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| Posted: Fri Feb 17, 2006 4:41 am Post subject: Re: In serious need of help |
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| AphroditeIncubus wrote: |
I need some serious help.. I have a gas law problem set and I can't figure out how to do some problems (my brain is fried) Could anyone help out? Any type of information will be most appreciated.
1) O2 has density of 1.43 g/L at STP. What will be the mass of 600.0 mL of O2 at 22.4 C and 742.5 mm Hg?
2)Chlorine diffuses 2.24 times faster than gas Q. What is the MW of gas Q?
3)Compute the volume in mL of 5.30 g CO2 at STP. |
1. Use the equation
Density = MP/RT
M is molar mass P is pressure in atmospheres and R is gas constant and T is temperature in kelvins.
Convert the stuff.
600ml/1000ml= .6 liters
22.4 +273= 295.4 degrees kelvin.
742.5 mm Hg/760 Atmospheres = .9769 atm
just plug into the equation after rearranging for M
(Density*RT)/P = M
(1.43 g/L*.0821*295.4)/.9769
= 35.45 g/mol O2.
And I'm a little stumped on the last step. You either multiply that answer by 18 or you divide it by 18 because that is the mass of water. Or you don't do anything to it. I'm not exactly sure.
Number two I can't remember the equation to use for that one
3).
First convert the grams to moles
5.30 g CO2/46g CO2
Then convert the moles to liters
.115 mol CO2* 22.4 L/mol
Convert that to mL
2.58L CO2*1000ml/L = 2580ml CO2
Hope that helps.
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