Consider these intermediate chemical equations. cap p sub 4 times s plus 3 cap o sub 2 g rightarrow cap p sub 4 cap o sub 6 s triangle cap h sub 1 is equal to negative 1 comma 640 kJ cap p sub 4 cap o sub 10 s rightarrow cap p sub 4 times s plus 5 cap o sub 2 g triangle cap h sub 2 is equal to 2 comma 940 point 1 kJ What is the enthalpy of the overall chemical reaction cap p sub 4 cap o sub 6 s plus 2 cap o sub 2 g rightarrow cap p sub 4 cap o sub 10 s ?