[sci0x]

Question
Hey have a question here:
You have equation for combustion of hydrogen chloride:
4HCl + O2 = 2Cl2 + 2H2O

Reaction is carried out in a collapsible vessel at 298K at pressure 1.01 x 10 to the power of 5 Pa. You have 8 moles HCl and 4 moles O2. What is the total volume of the gas at the beginning and end of reaction. And R = 8.314 J/K/mol.

Possible answer
Can you add 4 moles and 8 moles and say you have 12 moles to begin with.
And put that into pV = nRT formula to get V? But even if thats correct (which i doubt) how can you get the volume after unless it is the same before and after or something?

[Borek]

You are right as for the volume at the beginning. Then it is limiting reagent question, just don't forget about unreacted gas.

[Donaldson Tan]

how many moles of reactants are consumed in the reaction?

how many moles of products are formed in the reaction?

what is the net change in the number of moles of the system?