crazziekid82 Posted November 6, 2008 Share Posted November 6, 2008 ok im doing this question and i am totally lost. once again got the Q&A but no working out so i cant follow the steps to HOW they got the answer. So here it is Ammonia is produced in the Harber Process under conditions of high pressure and moderate temperture. If 13.05L of an equilibrium mix at 550'C (823K) and 200kPa presurre consists of 3.00 L of nitrogen and 9.00L of hydrogen and 1.50L of ammonia calculate teh density of (g) mixture.. im not sure where to start or what formulas to use. Link to comment Share on other sites More sharing options...
big314mp Posted November 6, 2008 Share Posted November 6, 2008 Well, density is mass per unit volume. You are given a volume, and you need to find the mass. To find the mass you will need to find the moles of each gas present, and then convert that into a mass. Link to comment Share on other sites More sharing options...
CaptainPanic Posted November 6, 2008 Share Posted November 6, 2008 Do you know the "Ideal gas law"? That's what I would use to calculate the density. Link to comment Share on other sites More sharing options...
pioneer Posted November 6, 2008 Share Posted November 6, 2008 What you do is PV=nRT for each of the components and solve for n. The T and P are the same for all, only V is different. We calculate n or the number of moles for each. Once we now the n for each, we can calculate the mass of each, which is molecular weight times the number of moles of each. Density is the total mass/volume. We add all the masses and divide by the total volume to get density at those conditions of T and P. Link to comment Share on other sites More sharing options...
hermanntrude Posted November 7, 2008 Share Posted November 7, 2008 it's easier than that. The ideal gas equation can be re-written to include density: PV = nRT PV = [math]\frac{m}{M}[/math]RT PV = [math]\frac{mRT}{M}[/math] P = [math]\frac{mRT}{VM}[/math] P= [math]\frac{mRT}{VM}[/math] PM = [math]\frac{mRT}{V}[/math] [math]\frac{PM}{RT}[/math] = [math]\frac{m}{V}[/math] = d the question is, though... which "M" should you use? 1 Link to comment Share on other sites More sharing options...
crazziekid82 Posted November 7, 2008 Author Share Posted November 7, 2008 can u add all the M values together then substitute into the EQN? Link to comment Share on other sites More sharing options...
hermanntrude Posted November 7, 2008 Share Posted November 7, 2008 i'm not sure if that would work. I would use P(a)V = [math]\frac{mRT}{M}[/math] three times to get the masses of the three gases and then use the version I already posted to get the density. This might not be the quickest route but it's the only one I can see. you'd have to first calculate the partial pressures of the gases using the volume ratio Link to comment Share on other sites More sharing options...
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