Ten kilograms of hydrogen gas are mixed with 355 kg of chlorine in a 0.50 mm^3 drum. The two gases react to produce hydrogen chloride. What is the final pressure in the drum if the final temperature is 60 degrees celcius?

Answer 1

H2 + Cl2 ==> 2HCl
moles H2 = g/molar mass = 10,000/2 = 5,000. That will produce 10,000 moles HCl.
moles Cl2 = 355,000/71 = 5,000 moles Cl2. That will produce 10,000 moles HCl.
Thus there is no limiting reagent; both reactants will be used to completion.
So you have moles, R, T (remember it must be in kelvin), and V. Solve for P. Note that the volume is in mm^3. I would convert that to cm^3 then to L.
0.5 mm^3 means the drum is 0.05 cm on an edge or 0.05^3 = ??cc = ??L.