ecoli Posted October 20, 2005 Share Posted October 20, 2005 Please help with this problem, I really think my method is right, but the book has different ideas. "The density of liquid nitrogen is 0.808 g/ml at -196 C. What volume of nitrogen gas at STP must be liquified to make 10.0 L of liquid nitrogen?" so [math] \ce{N2(g) -> N2(l)} [/math] The first step is to find the number of moles of N2, so g = D*V so g = [imath] .808 $g/ml$ * 10.0L[/imath] = 8.08 g moles = [imath] 8.08 g * \frac{1{mole}}{28.02g} [/imath] = .2883 moles V = nRT/P = [math] \frac{.2883 moles* .08206L atm/Kmol * 298K}{1atm} [/math] = 7.05 L the books answer is 6.46 * 10^3 L What did I do wrong? Link to comment Share on other sites More sharing options...
jdurg Posted October 20, 2005 Share Posted October 20, 2005 Don't forget that one Liter contains 1000 mL. Link to comment Share on other sites More sharing options...
P-man Posted October 20, 2005 Share Posted October 20, 2005 Man, I didn't know you could get that far in Chemistry and not even know your metric system... No offence or anything. Link to comment Share on other sites More sharing options...
ecoli Posted October 20, 2005 Author Share Posted October 20, 2005 Man, I didn't know you could get that far in Chemistry and not even know your metric system... No offence or anything. ouch...gotta say, that stung. Ok, so I change 10 L to 10,000 ml. That changes my answer to 7.05 L to 7.05 * 10^3 L...that's still not right. What else am I missing? Link to comment Share on other sites More sharing options...
ecoli Posted October 20, 2005 Author Share Posted October 20, 2005 oops used wrong temp... never mind. Link to comment Share on other sites More sharing options...
P-man Posted October 22, 2005 Share Posted October 22, 2005 I dunno. Link to comment Share on other sites More sharing options...
ecoli Posted October 22, 2005 Author Share Posted October 22, 2005 I dunno. What do you mean? I used room temp. (25 C) when I should have used standard temp. (0 C) Link to comment Share on other sites More sharing options...
P-man Posted October 23, 2005 Share Posted October 23, 2005 I think we must've posted at the same time, because when I replied, your second message wasn't there. Therefore my message corresponds to message #4, not message #5. Link to comment Share on other sites More sharing options...
ecoli Posted October 23, 2005 Author Share Posted October 23, 2005 I think we must've posted at the same time, because when I replied, your second message wasn't there. Therefore my message corresponds to message #4, not message #5. That's interesting... if you look at the time stamps you'll see that my message (5) was posted a full 22 hours before yours (6). Im pretty sure that's not at the same time. Link to comment Share on other sites More sharing options...
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