[chem4dummy]

ok this is an extra credit question, so it's really not an urgent matter.  Because it is an extra credit question I really don't think I have the slightest clue where to begin. 

The following reaction takes place in a sealed 40.0L container at a temperature of 393K. 
NH₃ + O₂ ---> NO + H2O

part A balance the equation-did that, that is the easy part
4NH₃ + 5O₂ ---> 4NO + 6H20

part B-When 34.0g NH₃ reacts with 96.0g O₂, what is the pressure of NO in the container?

part C-What is the total pressure of the gasses in the container?

I don't know where to begin or what gas law I am using.  I started by finding my moles of NH3 and O2.  and now am at a stand still.  Any help would be appreciated.  Even though it is just for extra credit I would like to understand this better.

[spock]

Good start.

Now figure out which reactant is the limiting reagent (the one that produces the least number of moles of NO).

The limiting reagent will determine the moles of NO produced (the smaller of the two from above).  Since you know the volume of the container (and any gase will have the volume of its container), the temperature of the gas, and the moles of NO, you can calculate the pressure of the NO using the ideal gas equation:
           P  = nRT/V

The limiting reagent will be used up, so that will not contribute to the final pressure in the container.

Calculate the moles of the reagent that is not the limiting reagent and calculate the pressure of that gas using the ideal equation as above.

From the coefficients it can be determined that for every 1 mole of NO, 1.5 moles of H2O gas will be formed (4:6 as 1:1.5).  Calculate the number of moles of H2O gas in the container and use the ideal gas equation as above.

Dalton's Law of partial pressures says that the total pressure in a mixture of gases is the sum of the partial pressure.  In this case, the sum of the pressures of the left over reactant, the NO, and the water vapor.
hey

[chem4dummy]

thanks for getting me started.  I think I've got the limiting found

2.00 moles NH3 x (4moles NO/4moles NH3)= 2.00 moles NO
                         3.00 moles O2 x (4moles NO/5 moles O2)= 2.4 moles NO

making NH3 limiting

putting this down for the night, will work on it some more tomorrow.  Thanks again
hey