Ice floats on water due to its density. Ice is the solid state of water. This state has well-defined structure, shape and volumes. Normally the density of a solid is greater than that of a liquid, but the opposite is the case for water.
At normal pressure conditions (one atmosphere), ice begins to be produced when the temperature is below 0 ºC.
Water and its density
Water molecules are made up of two hydrogen atoms and one oxygen atoms, with the representative formula H2O.
At normal pressures, water is in a liquid state, between 0 and 100 ° C. When water is in this state, the molecules move with a certain degree of freedom because that temperature provides kinetic energy to the molecules.
When water is below 0 ° C, the molecules do not have enough energy to move from one side to the other. Being close to each other, they interact with each other and are arranged in different ways.
All the crystalline structures that ice can have are symmetrical. The main arrangement is hexagonal and with hydrogen bonds that give a much larger space to the structure compared to that of water.
So, if for a given volume more water enters than ice, it can be said that the solid state of water is less dense than its liquid state.
Due to this difference in densities, the phenomenon of ice floating on water occurs.
Importance of ice
People and animals around the world benefit from this property of water.
As ice sheets form on the surfaces of lakes and rivers, the species that inhabit the bottom have a temperature slightly above 0 ° C, so living conditions are more favorable for them.
The inhabitants of areas where temperatures tend to drop a lot take advantage of this property in the lakes to skate and practice some sports.
On the other hand, if the density of the ice were greater than that of the water, the large caps would be under the sea and would not reflect all the rays that reach them.
This would considerably increase the average temperature of the planet. In addition, there would be no distribution of the seas as it is currently known.
In general, ice is very important since it has a myriad of uses: from refreshing beverages and preserving food to some applications in the chemical and pharmaceutical industry, among others.
References
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- Carrasco, J., Michaelides, A., Forster, M., Raval, R., Haq, S., & Hodgson, A. (2009). A one-dimensional ice structure built from pentagons. Nature Materials, 8 (5), 427-431. doi: 10.1038 / nmat2403
- Franzen, HF, & Ng, CY (1994). Physical chemistry of solids: Basic principles of symmetry and stability of crystalline solids. River Edge, NJ; Singapore;: World Scientific.
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