If you’ve ever asked yourself the question ‘why does ice float in liquid water?’, then we’ve written this article to answer it. Once you’ve finished reading you’ll be able to explain why ice floats.
We first have to look at water itself. It does not behave like other liquids. When you cool down most liquids, they’ll become heavier as they cool. Alcohol is one such example. Alcohol kept in a 30ºC container would weigh less than alcohol kept in a 10ºC container. The colder temperatures cause the density of the alcohol to increase, meaning more molecules of alcohol can fit in the same space.
However, water is most dense at 4ºC above zero. Below that temperature, things go into reverse and the density of the water decreases. Next time someone asks you ‘why is ice less dense than water?’, you can tell them this.
How Does Ice Float On Water?
If you’d like to know the details, we can dive a little further into the subject. A molecule of water has a single oxygen atom and two hydrogen atoms. Covalent bonds hold them together and prevent them from separating. But this only applies within a water molecule. The bonds between water molecules are not as strong. These bonds connect according to electrical charges. The positive hydrogen atoms in one molecule connect to the negative oxygen atom in another molecule.
When the water cools down, and goes below 4ºC, these bonds adapt so that the atoms of oxygen are kept separate. A pattern of crystal slowly starts to take shape at this point, and becomes solid once the water hits zero degrees Celsius. This is what we call ice, and if you’ve ever asked yourself or been asked ‘why does ice float on water?’, then the next section will answer that.
Why Does Ice Float?
Ice floats because its density is lower than the water surrounding it and beneath it. The precise figures show that ice is roughly nine percent lower in density than water. Ice also uses a greater amount of space than water does, which is why a container with ice inside will be lighter than a container with water inside. This is also why ice will rise to the top of any container with water in it.