Final answer:
Magnesium is isolated from seawater through a process involving precipitation, dissolution, evaporation, and electrolysis. It is prized in aircraft alloys for its lightweight and passivation properties and serves as an effective reducing agent in the production of various metals.
Step-by-step explanation:
Isolation of Magnesium from Seawater
The isolation of magnesium metal from seawater involves several chemical reactions. Initially, seawater, which contains magnesium chloride, is treated with calcium hydroxide to precipitate magnesium hydroxide. The magnesium hydroxide is then treated with hydrochloric acid, leaving behind pure magnesium chloride after evaporation. Finally, the magnesium chloride is subjected to electrolysis, where it is split into liquid magnesium and chlorine gas:
MgCl₂ (aq) + Ca(OH)₂ (aq) → Mg(OH)₂ (s) + CaCl₂ (aq)
Mg(OH)₂ (s) + 2HCl(aq) → MgCl₂ (aq) + 2H₂O(l)
Electrolysis of MgCl₂ (l) → Mg(l) + Cl₂(g)
Importance of Magnesium in Aircraft Alloys
Magnesium is used in aircraft alloys due to its lightweight properties, which contribute to the overall reduction of aircraft weight and thereby increase fuel efficiency. The malleability and ductility of magnesium at higher temperatures make it easy to work with. Additionally, magnesium's ability to form a passivating layer of magnesium oxycarbonate upon exposure to air decreases its inherent reactivity, which is beneficial for the construction of aircraft.
Role as a Reducing Agent
Magnesium serves as a reducing agent in the extraction of metals like uranium, titanium, and others. Using magnesium reduces a metal from its oxide form to the metallic form, which is often a less expensive method when compared to electrolysis.
Challenges in Magnesium Extraction
The extraction of magnesium from seawater presents several challenges, including the need for large amounts of energy for electrolysis and the need to control the removal of impurities during the process. Environmental considerations also play a role, as the use of chemicals and the release of chlorine gas must be managed responsibly.