The total surface area of the earth consisting of forest, cultivated land, grassland, and desert is 1.49 x 108 km2 . Every year, the mass of carbon fixed by photosynthesis by vegetation covering this land surface according to the reaction 6CO2 (g) + 6H2 O (l)------> C6H12O6(s) + 6O2 (g) is about 450. metric Tons km-2 . Calculate the annual enthalpy change resulting from photosynthetic carbon fixation over the land surface given above. Assume P=1 bar and T=298K.