What substances are more dense than water?
Solid water, ice, is less dense than its liquid state. This is essential for aquatic life. Since ice is less dense than liquid water, it floats to the top of of the water. This insulates the water beneath the ice, allowing the water beneath the ice to remain liquid. For other substances, the solid state is more dense than the liquid state.
How do waters relatives densities as a solid and a liquid differ from that of most other substances?
For most substances, the solid phase is more dense than the liquid and gas phases. The liquid phase is less dense than the solid phase but more dense than the gas phase, and the gas phase is less dense than either the solid or liquid phases. Water is an exception. Its solid phase (ice) is less dense than the liquid phase.
Most commonly available substances that are less dense than water is oil, alcohol and plastic. In fact, a number of organic solvents such as acetone, methanol and methylene chloride are also less dense than water. In addition, a number of different kinds of polymer are "lighter" than water, too. Hmm... potassium and sodium? :D
How do water's relative densities in solid and liquid forms differ from those of most other substances?
Most substances become more dense when they solidify, because the same amount of particles are taking up a smaller amount of space, but ice is actually less dense than water, and so it floats on water. --- Water's solid form is less dense than its liquid form, while the opposite is true of most other substances. --- Substances that change phase from liquid to solid when cooled have lower molecular pressure, and are typically denser…