What Is The Anomalous Expansion Of Water?

Water shows unusual expansion. If we take a cube of ice at -5°C and heat it, it expands till ice starts melting. During melting its temperature remains 0°C but its volume decreases. If heat is continuously supplied to water at 0°C, it further contracts up to 4°C and then it starts expanding. Thus water has its minimum volume and maximum density at 4°C.

The anomalous expansion of water helps preserve aquatic life during very cold weather. When temperature falls, the top layer of water in a pond contracts, becomes denser and sinks to the bottom. A circulation is thus set up until the entire water in the pond reaches its maximum density at 4°C. If the temperature falls further, the top layer expands and remains on the top till it freezes. Thus even though the upper layer are frozen the water near the bottom is at 4°C and the fishes etc. can survive in it easily.

Most of liquids expand on heating and contract on cooling. But expansion of water is remarkably so irregullar that even an ordinary laboratory methed can detect the anomaly. When water at 0c is heated,it contracts instead of expanding and after 4c it starts to expand till lts boiling point like other liquids. It is also observed that hot water when cooled, contracts upto 4c and it density is increased whereas it expands from 4c to 0c. Water at 0c chages to ice. Due to expansion the density of ice at 0c becomes less than water, that is why floats on water. As water, after contraction upto 4c, begins to expand so the density of water before and after 4c decreases. Thus at 4c water has maximum density and ;least volume. This unusual property water is called irregular or anomalous expansion of water.

Expansion of water as it is cooled from 4°C to 0°C. This behavior is unusual because most substances contract when they are cooled. It means that water has a greater density at 4°C than at 0°C. Hence ice floats on water, and the water at the bottom of a pool in winter is warmer than at the surface. As a result lakes and ponds freeze slowly from the surface downwards, usually remaining liquid near the bottom, where aquatic life is more likely to survive.
Normally, liquids contract on cooling & become more dense. However, water contracts when cooled to a temperature of 4oC and thereafter expands as it is cooled further from 4oC to 0oC. Water attains its maximum density at 4oC. This phenomenon is useful for the preservation of marine life in very cold temperatures. Initially, the surface water in water bodies starts cooling. Upon reaching the temperature of 4oC, the surface water descends to the bottom as it denser. Upon further cooling between 4-0 degrees C, a temperature gradient is set up in depths of the water body whereby, the bottom-most layer is at 4 deg C & the temperature gradually drops as one goes upwards. At 0 deg C, ice is formed. Ice being lighter than water, floats to the upper surface. Further, water and ice are bad conductors of heat. All this help in the maintenance of temperature of the water at the bottom at 4 deg C. It is in this layer that marine life is able to sustain itself.
Generally, all liquids expand due to heating. But water behaves in a peculiar way when heated from 0oC to 4oC. On heating from 0oC up to 4oC its volume decreases, reaches a minimum at 4oC such that the density of water is maximum at 4oC on heating further, water behaves like any other liquid. Similarly, during cooling process, the volume of water decreases up to 4oC, reaches a minimum at 4oC, if further cooled up to 0o C, its volume increases instead of decreasing and hence, density of water at 0oC is lesser than that at 4oC. Water freezes to ice at 0oC. Being less dense than water, ice floats on water. Beyond 4oC, water behaves like any other liquid.
This unique feature of water between 0 and 40C, is a boon to aquatic animals. Let us see how-

In cold countries and Polar Regions during winter, the temperature goes below 00C. In lakes and ponds when water at the surface reaches 40C, it is densest and goes to the bottom. When the temperature further reduces, only surface layers of water freeze whereas at the bottom water remains at 40C. Aquatic animals live comfortably in water at 40C ,whereas, outside temperatures may go much less than that.

When water is heated,it contracts up to 4degree Celsius,so it's density increases and above 4degree Celsius,it expands,so it's density decreases.
When hot water is cooled,it contracts up to 4degree Celsius and below
4degree Celsius it expands.So,water has maximum density at 4degree Celsius and it's density decreases below and above density at 4degree.

Natural convection and the anomalous expansion of water play important roles in saving the lives of aquatic animals  like fishes when the atmospheric temperature goes below 0 c .as water at surface is cooled,it becomes denser and goes down.
As water at the surface is further cooled,it expands and the density decreases .thus it remains at the surface and gets further cooled.finally,it start freezing.heat is now lost to the atmosphere by the water freezing.heat is now lost to the atmosphere by the water only due to conduction through the ice.as ice is poor conductor of heat,the further freezing is very slow.the temperature of the water at bottom remains constant at 4 degree C for the large period.

Generally when substances are cooled, they contract in size but this is not the case with water. When water is being cooled and when the temperature is being lowered from 4°C to 0°C, water starts expanding. When frozen water can expand up to 9% in volume which means that it can rapture the container if t is totally filled with water on freezing. This behavior is unusual so it is called the anomalous behavior. This means that the density of water is lesser at 0°C as compared to other temperatures so ice floats on water and it always freezes top down. This phenomenon helps the sea creatures survive under the thick layer of ice on the surface of water during winters as it insulates the rest of the water.

Most of the liquids expand on heating and contract on cooling.But water shows a marked expectional behaviour between 0 degree celcious and 4 degree celcious.When water is heated from 0 degree celcious and 4 degree celcious it contracts its volume upto 4 degree celcious.Its volume becomes minimum at 4 degree celcious.Beyond 4 degree celcious its volume goes on increasing.There on heating from 0 degree celcious to 4 degree celciousthe denstiy of water increases and becomes maximum at 4 degree celcious.this exceptional behaviour of water between 0 degree celcious and 4 degree celcious is known as anomalous expansion of water...

It is different character among other .The basic property of liquid is that expands by increasing temperature and condense by decreasing the temperature .But water condense from zero degree to 4c .At 4c it shows expansion till boiling points by increasing  the temperature .If we decrease the temperature from the boiling point water shows contraction to four degree centigrade and now from four to zero degree centigrade shows expansion. This is called anomalous  expansion of water.

Generally all the liquids expand in volume when they are heated but water decreases in volume  when heated from 0c to 4c and then after 4c, it increases its volume on further heating. The volume of a fixed mass  of water is minimum  at 4c i.e. Its density is maximum at 4c with further rise in temperature its density decreases.  Daneshwar..

At + 4 deg C - fresh water has an anomalous expansion, the molecular structure expands - rather than contracts. The result is less dense water remaining on the surface, rather than sinking, and being replaced by warmer water from below. The net result is the ice forms on the surface at zero deg C, and grows downwards, rather than sinking, and growing upwards. It has been mooted that salt water freezes at -1.9 deg C, but actually the salt water never freezes - the fresh water particles freeze, and exclude the salts - which become brine as the salinity increases - requiring a greater negative temperature to freeze.

A Maytham FRMetS

The unusual behavior of water in expansion and contraction between 0c to 4c is called anomalous expansion of water

The peculiar behaviour of water from 0 to 4c is known as anomalous expansion of water.

The expansion of water when it is cooled from 4 degree Celsius to 0 degree Celsius is known as anomalous expansion of water... Effect in daily life- the anomalous expansion of water is responsible for the burst of water pipe lines,nerves of plants and rocks during the very cold nights when the atmospheric temperature falls to 0 degree Celsius

Expansion of water as it is cooled from 4°C to 0°C. This behaviour is unusual because most substances contract when they are cooled. It means that water has a greater density at 4°C than at 0°C. Hence ice floats on water, and the water at the bottom of a pool in winter is warmer than at the surface. As a result lakes and ponds freeze slowly from the surface downwards, usually remaining liquid near the bottom, where aquatic life is more likely to survive.

All solids expand when heated and contract when cooled but water is an exception a sit expands when cooled from any temperature until 4 degree celcius when it starts to expand if cooled bellow its temperature. The anomalous expansion is of great importance inn nature. Lakes,ponds and rivers freeze from the top surface rather than from the bottom and thus marine life can survive under the the water as it remains at a constant temperature of 4 degree celcius

I need the proper definition of anomalous expansion of water

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There are many uses of anomalous behavior of water
The anomalous expansion of water helps preserve aquatic life during very cold weather. When temperature falls, the top layer of water in a pond contracts, becomes denser and sinks to the bottom. A circulation is thus set up until the entire water in the pond reaches its maximum density at 4°C. If the temperature falls further, the top layer expands and remains on the top till it freezes. Thus even though the upper layer are frozen the water near the bottom is at 4°C and the fishes etc. Can survive in it easily.

We know that most substances contract when they are cooled but Water Expands when cooled from 4°C to 0°C. This unusual Expansion of water is Anomalous expansion of water. This shows water's  greater density at 4°C and lower density at 0°C. Hence ice floats on water, and the water at the bottom of a pool in winter is warmer than at the surface keeping aquatic life under water safe.
To help you more,
Here is a very detailed and to-the-point article on Anomalous Expansion Of Water for all the details and answers on your topic along with This short article.

It is the expansion of water below 4 degree celsius.

Abnormal expansion of water where it expands on cooling and contracts on heating.Greatly explained in a fish pond!

The anomalous expansion of water is the unusual expansion of water that is within the range of 0^c to 4^c.

Water is apparently a molecule and its chemical term is (H₂O). It is a highly complex character. Water has high viscosity that is why it can form in to any shape. There is no particular arrangement of water which can make water to behave differently.well by adding some chemicals you can change water in to many other forms like soft drinks.
Water has many advantages like it can saturated with any substance.
 
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It is the unusual expansion of water......

Anomalous expansion of water is the unusual expansion of water .water when goes below 0 degree expands .

Water increases its size when frozen this is the anomalous expansion of water.