Phosphoric acid (H3PO4) is an important industrial chemical used in fertilizers, in detergents, and in the food industry. It is produced by two different methods. In the electric furnace method, elemental phosphorus (P4) is burned in air to form P4O10, which is then reacted with water to give H3PO4. In the wet process, the mineral phosphate rock fluorapatite [Ca5(PO4)3F] is reacted with sulfuric acid to give H3PO4 (and HF and CaSO4). Write equations for these processes and classify each step as precipitation, acid-base, or redox reaction.