What are the differences between ice and water?

Answer 1

The following are a few differences between water and air (there are many more): Water is a liquid and air is a gas Water is a compound consisting of 2 parts hydrogen atoms and 1 part oxygen atoms, and air is about 79% nitrogen gas and 20% oxygen, plus small amounts of many other gases. The volume of water changes very little with changes in temperature and pressure, and the volume of air changes in direct proportion to temperature and pressure changes Water is odorless and air has an aroma depending upon the substances in it.

Answer 2

Ice is the solid form of water, usually achieved by lowering water below zero (its freezing point). Ice is still water (H20) but just colder.

What's the difference?

In a glass of liquid water, we have an unimaginable number of H2O molecules, slipping and sliding past one another. They make some (relatively) weak intermolecular bonds (hydrogen bonds!) and break them just as fast. They don't have enough energy to fly off into the air (steam) but they have too much energy to stay in one place (ice).

In a glass of ice we have the same number of H2O molecules but they have less thermal energy. They can't keep breaking those intermolecular bonds and so they're locked in a solid structure that does not flow as water does.

Interestingly, the structure of ice is very predictable - water will organize itself into a crystal structure that is the same organization of bonded H2O molecules repeated throughout the block of ice. This is because this organization is very convenient for the molecules, they're under no strain and so structure is low in energy, meaning no change is energetically encouraged. It also happens that this structure takes up a bit more space than liquid water does.

This is why ice takes up more space than water, why ice is less dense and thus why ice floats. It's also why you can crush surface ice into liquid water when you ice skate along it, allowing you to glide across the ice.