Water Anomalyous

Observe a glass of iced water, what did you see?

Does the ice float or sink?

Ice always floats in water, isn't it?

Since ice floats in water, it means ice has lower density than water.

Lower density can be caused by:

1. Increase the volume

2. Decrease the mass

How about ice? What happen to ice to make it lower in density? Did you decrease the mass of water to be made into ice?

Of course not, generally all things will remain in mass, but change in volume (because of thermal expansion, it could expand or contract actually)

When we make ice from water, there's no changing in mass, the one which changing is state (phase, from liquid to solid).

Normally, during cooling, all matters will contract, so the volume will decrease.

However, that's not happening to water when they are changing into ice, water will expand (when we put in freezer, to make ice), that will lead to the increase of volume.

If you notice, everytime you make ice cube in a container, you will see that ice will fill the container more than you put before (when remain as water), so it is clear that ice has higher volume than water.

Since ice has higher volume than water, it means when ice melt to water, the ice will decrease in volume, to become water, normally.

But then will water remain normal? Or will it expand under hot condition and contract under cold condition?

Of course.

This will occur at 4 C and above.

That's why we say there is a strange property of water when become ice or ice when become water (anomalyous of water).

This phenomenon only occurs at 0 - 4 C.

Observe the graph below to see how volume of water interact to temperature.

You can see that at 4 C the water will reach its minimum volume, so it means the density will be the highest and then the density will increase comparable to the temperature and so on.