Polar ice blocks and icebergs drift in the ocean, and even in drinks, ice never sinks to the bottom. It can be concluded that ice does not sink in water. Why? If you think about it, this question may seem a little strange, because the ice is hard and - intuitively - should be heavier than liquid. Although this statement holds true for most substances, water is an exception to the rule. Water and ice are distinguished by hydrogen bonds, which in the solid state make ice easier than when it is in a liquid state.
Scientific question: why does not ice sink in water
Imagine that we are in a lesson called “The World” in grade 3. “Why doesn’t the ice sink in the water?” The teacher asks the children. And the kids, not having deep knowledge in physics, begin to reason. “Maybe it's magic?” - declares one of the children.
Indeed, ice is extremely unusual. There are practically no other natural substances that, in the solid state, could float on the surface of a liquid. This is one of the properties that makes water such an unusual substance and, admittedly, it is it that changes the evolutionary planets.
There are some planets that contain a huge amount of such liquid hydrocarbons, such as ammonia - however, when freezing, this material sinks to the bottom. The reason why ice does not sink in water is that when it freezes, the water expands, and at the same time its density decreases. Interestingly, the expansion of ice can break stones - the process of glaciation of water is so unusual.
In scientific terms, during the freezing process, fast weathering cycles are established and certain chemicals released on the surface are able to dissolve minerals. In general, such processes and possibilities are associated with the freezing of water that the physical properties of other liquids do not imply.
Density of ice and water
Thus, the answer to the question of why ice does not sink in water, but floats on the surface, is that it has a lower density than liquid - but this is the first level answer. For a better understanding, you need to know why ice is low in density, why things come up in the first place, how density leads to swimming.
Recall the Greek genius Archimedes, who found that after immersing a certain object in water, the volume of water increases by a number equal to the volume of the immersed object. In other words, if you put a deep dish on the surface of the water, and then place a heavy object in it, the volume of water that will pour into the dish will be exactly equal to the volume of the object. It does not matter if the object is immersed in whole or in part.
Water properties
Water is an amazing substance that basically feeds life on earth, because every living organism needs it. One of the most important properties of water is that it has the highest density at 4 ° C. So, hot water or ice is less dense than cold water. Less dense substances float on top of denser substances.
For example, during the preparation of a salad, you may notice that the oil is on the surface of vinegar - this can be explained by the fact that it has a lower density. The same law is also valid for explaining why ice does not sink in water, and sinks in gasoline and kerosene. Simply, these two substances have a lower density than that of ice. So, if you launch an inflatable ball into the pool, it will float to the surface; if you throw a stone into the water, it will sink to the bottom.
What changes occur with water when freezing
The reason why ice does not sink in water is due to hydrogen bonds, which change when water freezes. As you know, water consists of one oxygen atom and two hydrogen atoms. They are attached by covalent bonds that are incredibly strong. However, the other type of bond that forms between different molecules, called the hydrogen bond, is weaker. These bonds are formed because positively charged hydrogen atoms are attracted by negatively charged oxygen atoms of neighboring water molecules.
When the water is warm, the molecules are very active, move a lot, quickly form and decompose bonds with other water molecules. They have the energy to move closer to each other and move fast. So why doesn't ice sink in water? Chemistry hides the answer.
Physical chemistry of ice
As the water temperature drops below 4 ° C, the kinetic energy of the liquid decreases, so the molecules no longer move. They have no energy to move and as light as at high temperature, to break and form bonds. Instead, they form more hydrogen bonds with other water molecules to form hexagonal lattice structures.
They form these structures in order to support negatively charged oxygen molecules from each other. In the middle of hexagons formed as a result of the activity of molecules, there is a lot of emptiness.
Ice sinks in water - reasons
Ice is actually 9% less dense than liquid water. Therefore, ice takes up more space than water. In practice, this makes sense because the ice is expanding. That's why it is not recommended to freeze a glass bottle of water - frozen water can create large cracks even in concrete. If you have a liter bottle of ice and a liter bottle of water, then a bottle of ice water will be easier. Molecules are further apart at this point than when the substance is in a liquid state. That is why ice does not sink in water.
When the ice melts, the stable crystalline structure breaks down and becomes denser. When water warms up to 4 ° C, it receives energy, and molecules move faster and further. For this reason, hot water takes up more space than cold water, and floats on top of cold water - it has a lower density. Remember, when you are on the lake, while swimming, the upper layer of water is always pleasant and warm, but when you lower your legs deeper, you feel the cold of the lower layer.
The value of the process of freezing water in the functioning of the planet
Despite the fact that the question is “Why doesn't ice sink in water?” for grade 3, it is very important to understand why this process is happening and what matters to the planet. So, the buoyancy of ice has important consequences for life on Earth. Lakes freeze in winter in cold places - this allows fish and other aquatic animals to survive under an ice sheet. If the bottom froze, it is highly likely that the whole lake could be frozen.
Under such conditions, not a single organism would survive.
If the density of ice were higher than the density of water, then in the oceans the ice would fall, and the ice caps, which would then be at the bottom, would not allow anyone to live there. At the bottom of the ocean would be full of ice - and what would it all turn into? Among other things, polar ice is important because it reflects light and protects planet Earth from overheating.