Magnesium is lighter than other structural metals, so it is increasingly important in the design of more efficient vehicles. Mg²⁺ ions are present in seawater, and the metal is often prepared by “harvesting” these ions and converting them to Mg metal. The average magnesium content of the oceans is about 1270 g Mg²⁺ per ton of seawater, and the density of seawater is about 1.03 g/mL. What is the molarity of Mg21 ions in seawater? The design for a concept car calls for 103 kg of magnesium per vehicle. How many gallons of seawater would be required to supply enough magnesium to build one of these cars?