Water is denser as a liquid than as a solid. In which phase is water denser?

Water is denser as a liquid than as a solid. In which phase is water denser?

• A. Liquid
• B. Gas
• C. Solid
• D. Plasma

Answer: (A)

Density tells us how tightly packed the molecules are in a phase. For water, the solid form (ice) forms a hydrogen-bonded lattice that creates open spaces, so it isn’t packed as tightly as liquid water. When ice melts, those bonds break and the molecules can come closer together, making liquid water about as dense as 1.00 g/cm^3 at around 4°C. As a result, the liquid is denser than the solid. Gas has molecules far apart and is far less dense, and plasma isn’t a typical phase for water under ordinary conditions. So the phase where water is densest is the liquid.

Density tells us how tightly packed the molecules are in a phase. For water, the solid form (ice) forms a hydrogen-bonded lattice that creates open spaces, so it isn’t packed as tightly as liquid water. When ice melts, those bonds break and the molecules can come closer together, making liquid water about as dense as 1.00 g/cm^3 at around 4°C. As a result, the liquid is denser than the solid. Gas has molecules far apart and is far less dense, and plasma isn’t a typical phase for water under ordinary conditions. So the phase where water is densest is the liquid.