(a) The first step is the decomposition of solid calcium carbonate from seashells to form solid calcium oxide and gaseous carbon dioxide. (b) The second step is the formation of solid calcium hydroxide as the only product from the reaction of the solid calcium oxide with liquid water. (c) In the third step, calcium hydroxide (mixed with seawater) reacts with dissolved magnesium chloride to yield solid magnesium hydroxide and aqueous calcium chloride. (d) In the fourth step, solid magnesium hydroxide is added to an aqueous hydrochloric acid solution, producing dissolved magnesium chloride and liquid water. (e) Finally, the magnesium chloride is melted and this liquid is electrolyzed to yield liquid magnesium metal and diatomic chlorine gas