The heat of combustion of CH4 (g) at constant volume is measured in a bomb calorimeter at 298.2K and found to be - 885389J/mol. Find the value of enthalpy change.
How ∆n can be -2? If you write the equation of the reaction you will get CH4 +2O2 -------> CO2 + 2H2O If you see the equation then you will find total no. of moles in product is 2+1=3 and total no. of moles in reactants is 1+2=3. So ∆n = 3-3 = 0 So, how did you get ∆n = -2 ?