Question

Nitric acid, a very important industrial chemical, is made by dissolving the gas nitrogen dioxide (NO2) in water. Calculate the moles of gas produced in 2 L volume container, 736 torr and 50 ºC if the gas behaves as ideal:

Answer 1

I haven't done this in years... but looks like you can do this using the formula PV = nRT if I remember correctly where P = pressure in atm, V = volume in L, n = number of moles, R = 0.0821 (atm*L*K)/mol "I'm not so sure about the unit on R", and T = temperature in Kelvin.

Answer 2

NO2 is not the anhydrous form of HNO3. N2O5 is. When NO2 is dissolved in water a mixture of HNO2 and HNO3 is produced. Commercially, O2 is added to oxidize the HNO2 to HNO3. Since the HNO3 produced is an aqueous solution, I don't understand calculating mols of a gas.
Concerning R, it the units are L*atm/mol*K.
2NO2 + H2O ==> HNO2 + HNO3