We write the combustion rxn for hexanes, #C_6H_14#...
#C_6H_14(l) + 19/2O_2(g) rarr 6CO_2(g) + 7H_2O(g) + Delta#
And is this balanced?
We gots #(1000*g)/(86.18*g*mol^-1)=11.6*mol# with respect to hexanes...
And we need #19/2*"equiv"# of dioxygen....
i.e. #19/2*molxx11.6xx32.00*g*mol^-1-=3527.5*g#.
Now we gots #14.7*kg# air, which is #23.2%# by MASS dioxygen, i.e. #3.41*kg#. So we haven't got quite enuff dioxygen for complete combustion....we could invoke incomplete combustion, i.e.
#C_6H_14 + 9O_2 rarr 5CO_2(g) + CO(g) +7H_2O(g)#
But I am not going to bother because the question is poorly proposed.
So finally, if you start with #15.7*kg# of reactant, you are going to finish with #15.7*kg# of product in whatever form... Conservation of mass, an absolute property of EVERY chemical reaction, confirms this.
