Answer Show  Hint: When water freezes, formation of ice takes place. It changes from liquid to solid state. Water crystallizes into hexagonal structure. It begins to take a more stable and definite shape. Complete step by step answer: The normal behavior observed in any substance is that they usually expand when heated as their density decreases and contracts on cooling as their density is maximum. But water is an exception. Water has a special property which is known as anomalous expansion of water. Because of this property, water when it freezes, its density becomes maximum value upto \[{{4}^{{}^\circ }}C\]. After that when the temperature of water changes from \[{{4}^{{}^\circ }}C\text{ to }{{\text{0}}^{{}^\circ }}\text{C}\] the density of water decreases and hence water starts to expand. When water freezes, its molecules form a hexagonal structure and therefore its size expands. Water molecules contain two hydrogen atoms and one oxygen atom. Water molecules are held together by intermolecular force of attraction. In liquid state water molecules can freely move around the container. They do not have any specific arrangement. There is a force of attraction between the hydrogen atom of one water molecule and oxygen atom of another water molecule. Although this force is not that strong compared to O-O attraction.When the water begins to freeze into ice, the water molecules are held by H-O bonds. This bond is not as tight as an O-O bond. As the H-O force of attraction is present in ice, its size expands.Therefore, the statement saying water contracts on freezing is a false statement. Additional information: There are other substances which can expand upon freezing. They are:- Bismuth- Gallium- Acetic acidNote: - The anomalous expansion property of water helps to preserve the lives of aquatic plants and animals in cold climate. - The way this property protects marine life is that during cooling of water, it becomes very dense at \[{{4}^{{}^\circ }}C\]. Due to maximum density the water at the top layer reaches the bottom and the lightest water at the bottom of the water body comes to the top. This lightest layer at the top is the first one to get frozen. After the top layer is completely frozen, it will not allow the cold of the winter to reach the bottom. This is because water and ice are insulators. Hence protecting the aquatic lives.
QUESTION #371 Asked by: Remi Short Answer: by about 9% to 10% Long Answer: Normally, things expand when heated and contract when cooled. Water is an exception to this rule. Even though water does expand when heated and contract when cooled at most temperatures, water expands when cooled and contracts when heated between 4 degrees Celsius and 0 degrees Celsius. A very good web site about the properties and oddities of water can be found on the Okanagan University, Dept. of Geology website at: http://www.geog.ouc.bc.ca/physgeog/contents/8a.html Answered by: Charles Hill, Network Engineer, Deltona, FL
Below 4°C, the hydrogen bonds between water molecules become stronger and cause the matter to expand. Because the bonds between water molecules are stronger, they are less likely to break and re-form as they do in the liquid state. As a liquid, water molecules are constantly moving (forming and breaking hydrogen bonds) resulting in less expansion. When frozen, water molecules take a more defined shape and arrange themselves in six-sided crystalline structures. The crystalline arrangement is less dense than that of the molecules in liquid form which makes the ice less dense than the liquid water. When water freezes, the volume expands by approximately 9%. Solid and Liquid structures of Water
Yes. Ice has a lesser density than water. How Much Does Water Expand When It Freezes?
Approximately by about 9% – 10%. Why? – The Cause behind the Effect
On heating, liquids expand since the molecules move with greater energy overcoming the intermolecular attraction. On the contrary, liquids usually contract on cooling. It is because the molecules move slower and are not able to overcome the force of attraction between them. When they freeze, they contract some more to form a rigid solid structure with minimal intermolecular spaces between them. But that is not the case with water. Instead of contracting, it expands. The Molecular StandpointThe water molecule, consisting of 2 atoms of hydrogen and one of oxygen forms a Mickey Mouse head-like structure such that the ears are the hydrogen atoms and the head is represented by the oxygen atom. The oxygen atom side of the molecule is slightly negative while the hydrogen atoms side has a slight positive charge. This makes the water molecules drawn towards each other forming hydrogen bonds. Upon freezing, the molecules set themselves in an arrangement that is very open in nature and contains more space than the water in the liquid state. Hence, water is said to expand on freezing and becomes less dense. On the other hand, it contracts on thawing, much unlike most other liquids. How Does Water Expand When It Freezes?
In fact, water also shows the normal behavior of contracting due to cooling up to 4° C. But on cooling to temperatures below that, it starts expanding in volume. This is because the molecules start to get into a stable hexagonal lattice structure, as mentioned above. It is a very open structure with a lot of intermolecular space. Hence the expansion. The same applies when finally it freezes to ice at 0° C. Is Water The Only Substance That Expands When It Freezes?
No, it is not. Other such substances include plutonium, germanium, bismuth, gallium, silicon, acetic acid, etc. Video
Here is a video explanation to make it simple for you. This phenomenon, also known as the anomalous expansion of water is the reason why water bottles crack on freezing of the water inside. Another effect of this is the floating of ice cubes in water. It is because ice is of lesser density than water due to the reason mentioned above.
Article was last reviewed on Thursday, October 29, 2020 |
When water freezes it contracts or expands
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