Water freezes at 0°C because it is at this temperature that the cohesive forces between water molecules outweigh thermal agitation, allowing for the formation of the solid crystalline structure of ice.
Water is composed of H₂O molecules, with an oxygen atom bonded to two hydrogen atoms. This structure forms a polar molecule, with one side slightly negative (the oxygen) and one side positive (where the hydrogen atoms are located). At room temperature, the molecules move freely. As the temperature drops towards 0°C, their agitation decreases. As a result, the molecules slow down to the point of starting to assemble together due to their opposite charges. They eventually adopt a stable, geometric, and less mobile arrangement: thus, we gradually transition to the solid state, which is ice.
The way water freezes mainly depends on small connections called hydrogen bonds. These bonds, weak but numerous, link water molecules to each other like mini magnets. When hot, they break and reform continuously: water is liquid. But as the temperature drops towards 0°C, these bonds last longer, stabilizing the molecules together. At this point, the water molecules slow down, gradually organize, and ultimately freeze in place. The result: they arrange themselves into a precise structure, forming a solid known as ice. Without these hydrogen bonds, the transition of water from liquid to solid would clearly not occur in this very particular way.
When water freezes, its molecules slow down so much that they organize themselves in a very structured way, forming a regular network called a crystal. This crystal takes on a particular shape known as hexagonal structuring, similar to a honeycomb architecture or snowflakes. This structure arises from the famous hydrogen bonds, which firmly hold the molecules together by creating regular spaces. And it is precisely because of these very organized spaces that ice takes up more space than liquid water, which explains why it floats. This peculiarity means that ice is less dense than water: yes, you understood correctly, the solid version of water is therefore lighter than its liquid phase!
Normally, it is said that water freezes at 0°C, but in reality, it also depends a bit on atmospheric pressure. When the pressure changes, the temperature at which water becomes ice can also shift slightly. For example, if the pressure increases significantly, ice starts to melt more easily: water remains liquid even below 0°C. Conversely, under lower pressure (like at high altitude, where there is less air above your head), ice will form at a temperature that is close, but very subtly different. This phenomenon explains why at the summit of Everest, where the pressure is much lower, water freezes at a temperature very slightly above 0°C. It’s subtle, yes, but it exists!
Water definitely doesn't behave like everything else. Unlike most substances, it expands when it freezes. As a result, ice floats on liquid water, which is frankly unusual. Generally, when a substance cools, it becomes denser and contracts, but for water, this phenomenon reverses at around 4°C. This means that instead of sinking to the bottom, ice remains on the surface, which protects aquatic life below during winter. Another peculiarity: water has a remarkably high specific heat—essentially, it takes a long time to heat up or cool down, which helps regulate the climate on Earth. These amazing quirks primarily arise from the famous hydrogen bonds, those "little friendship links" that make water so special.
Unlike most substances, water expands in volume when it freezes: ice occupies about 9% more volume than liquid water, which explains why ice cubes float on the surface of your drink.
Under certain conditions of high purity and absence of impurities, water can remain liquid below 0°C, a phenomenon known as supercooling. A simple shock or a slight disturbance is enough for it to freeze instantly!
At high altitudes, due to the lower atmospheric pressure, water boils at a much lower temperature than 100°C, thereby altering its physical properties, and the temperature required for it to freeze can also vary slightly.
Naturally formed ice generally takes on a hexagonal structure, which explains the recurring appearance of beautiful symmetrical patterns in snowflakes visible to the naked eye.
Yes, atmospheric pressure slightly influences the freezing temperature. At very high altitudes, where pressure decreases, water freezes at a slightly different temperature, but the variation is minimal, almost imperceptible in daily life.
When salt is dissolved in water, it disrupts the regular arrangement of molecules needed to form ice. As a result, a lower temperature is required for crystallization to occur, which is known as freezing point depression.
No, each substance has its own freezing point, which depends on the specific interactions between its molecules. For example, pure alcohol freezes at around -114°C, while mercury freezes at about -39°C.
Yes, this is what is called 'supercooling'. Pure water, without impurities or motion, can temporarily remain liquid below its normal freezing point. However, at the slightest shock or disturbance, it will freeze instantly.
During solidification, water molecules organize themselves into a hexagonal crystalline structure due to hydrogen bonds, which causes them to occupy more space and increases the overall volume. This is why ice floats on liquid water.
0% of respondents passed this quiz completely!
Question 1/6
