Which observation is NOT seen when lithium reacts with water?

Which observation is NOT seen when lithium reacts with water?

• A. Fizzing
• B. Lithium disappears
• C. Floats
• D. Melts

Answer: (D)

When lithium reacts with water, it undergoes a rapid, exothermic redox reaction that forms lithium hydroxide and hydrogen gas. The fizzing you see comes from the hydrogen gas bubbles. The lithium piece floats because its density is less than that of water, so it sits on the surface. It may seem to disappear as it is converted into Li+ ions in solution. Melting would require the solid lithium to stay as a metal and change to a liquid phase. In this reaction, the metal is consumed to form ions and compounds far more quickly than it could reach its melting point, so you don’t observe a separate liquid metal.

When lithium reacts with water, it undergoes a rapid, exothermic redox reaction that forms lithium hydroxide and hydrogen gas. The fizzing you see comes from the hydrogen gas bubbles. The lithium piece floats because its density is less than that of water, so it sits on the surface. It may seem to disappear as it is converted into Li+ ions in solution.

Melting would require the solid lithium to stay as a metal and change to a liquid phase. In this reaction, the metal is consumed to form ions and compounds far more quickly than it could reach its melting point, so you don’t observe a separate liquid metal.