posted a question
acetylene (C2H2) torches are used in welding. How much heat in kJ evolves when 5.0g of C2H2 (d=1.0967kg/m^3) is mixed with a stoichiometric amount of oxygen gas? The combustion reaction is

C2H2(g) + 5/2 O2 (g) --> CO2 (g) + H2O(l) (heat of reaction is . -1299.5kJ