## Note on Anomalous Expansion of Water

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Generally, the volume of substances increases on heating and decreases in cooling. But when water is heated from 0 degree Celsius to 4 degree Celsius, its volume decreases and increases only after 4 degree Celsius. This unusual behavior of water from 0 degree Celsius to 4 degree Celsius is known as anomalous expansion of water.

As density is inversely proportional to volume, so, density of water increases from 0 degree Celsius to 4 degree Celsius.

At 4 degree Celsius, water has minimum volume and maximum density.

The graphical representation of volume and density of water with temperature is given below:

### Application of anomalous expansion of water:

In cold countries, when temperature falls below 0 degree Celsius, aquatic life can survive due to anomalous expansion of water.

When the temperature of surrounding reaches up to 4 degree Celsius, the upper surface of the pond will have maximum density and so it sinks to the bottom of the pond. When temperature falls to 3 degree Celsius, it expands and its volume increases but density decreases than that of 4 degree Celsius. So, water at 3 degree Celsius lies above the water at 4 degree Celsius. This process continues until water temperature reaches to 0 degree Celsius. The ice has less density than water. So, it floats on upper surface of the pond as ice is bad conductor of heat, it does not allow heat to escape out of the pond. Hence, aquatic life can survive when temperature falls below 0 degree Celsius,

As we know, water has minimum volume of 4 degree Celsius. So, due to anomalous expansion of water, whether it is heated or cooled, and its volume increases and so it overflows from the beaker.

In refrigerator when temperature falls below 4 degree Celsius to 0 degree Celsius, due to anomalous expansion of water, water in the bottle expands. Since there is no space for expansion of water filled in the bottle, it exerts larger force in the walls of bottle and it bursts.

Bottles of soft drink are kept in refrigerator for cooling water, temperature of refrigerator falls below from 4 degree Celsius to 0 degree Celsius, water in the bottle of soft drink expands due to anomalous expansion of water, and that empty space is filled with water which prevent the bottle from bursting.

In cold countries, water pipes expand. Since, there is no space for expansion, water exerts large force on the wall of pipe and it bursts.

• The volume of substances increases on heating and decreases in cooling. But when water is heated from 0 degree Celsius to 4 degree Celsius, its volume decreases and increases only after 4 degree Celsius. This unusual behavior of water from 0 degree Celsius to 4 degree Celsius is known as anomalous expansion of water.
• When the temperature of surrounding reaches up to 4 degree Celsius, the upper surface of the pond will have maximum density and so it sinks to the bottom of the pond.
• In cold countries, water pipes expand. Since, there is no space for expansion, water exerts large force on the wall of pipe and it bursts.
.

### Very Short Questions

The unusual behavior of water that expands on cooling from 4 0C to 0 0C is called anomalous expansion of water. It is called unique because it is not possible in other substance and is a particular nature of water.

Due to anomalous nature the volume of water is minimum at 4 o C temperature and increase above and below 4 o C temperature. Hence, if water is cooled down below 4 o C temperature the volume of water increases and water pour out from the beaker. The process takes place up to 0 o C temperature. After then water froze to ice.

A bottle completely filled with water gets burst when it is kept in a refrigerator because the temperature inside the refrigerator decreases the temperature of water below freezing temperature. When water freezes to ice, the volume of ice increases. The increase in volume gives very large force on the bottle that gets burst.

When a beaker completely filled with water of 4 o C is heated or cooled, water overflows because of anomalous expansion of water. The volume of water increase even when temperature falls and as usual the volume increases with increase in temperature.

4 o C is the temperature of water at the bottom of a pond when its surface water freezes. During very cold weather, as the temperature of a pond falls, the water at the free surface of the pond contracts, becomes denser and flows to the bottom. This process is continued until all water reaches at 4 o C. If further cooling occurs, the cooled water stay at the top and it doesn't flow to the bottom. So, even its surface water freezes, the temperature of water remains 4 o C at the bottom of the pond.

Due to the anomalous expansion of water, when it is heated up to 4 o C, Its volume decreases and density increases. In a pond the water at 4 o C is collected at the bottom while above it there are other layers of water at 3 o C, 2 o C, 1 o C and 0 o C respectively. As the density of ice is less than that of water it floats on the surface. This ice does not allow the heat of pond water to escape out as it is insulator of heat. Hence, fish can survive under a pond whose surface is even covered with ice.

Here,

Mass of water (m) = 100g = $$\frac{100}{1000}$$kg

= 0.1 kg

Initial temperature (t1) = 5°C

Final temperature (t2) = 90°C

∴ Rise in temperature (dt) = t2-t1

= 90-5

=85°C

sp. heat capacity of water (s) = 4200Jkg-1°C-1

∴ amount of heat supplied (Q) =?

We have,

Q = msdt

= 0.1×4200×85

= 38700J

Hence, the amount of heat supplied to water is 35700J

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• ### This unusual behavior of water from 0 degree Celsius to 4 degree Celsius is known as ______.

none of above
different behaviour
anamolous contraction of water
anamolous expansion of water
• ### At 4 degree Celsius, water has ______.

minimum density

maximum volume.

minimum density and maximum volume.

minimum volume and maximum density.

• ### In cold countries, water pipes expand due to _______.

freezing point

anamolous expansion of water

different behaviour

anamolous contraction of water

• ### What is the density of water at 40C?

200 kg per cubic meter
3000 kg per cubic meter
999.702 kg per cubic meter
1000 kg per cubic meter
• ### The unusual behaviour of water that expands on cooling from 40C to 00C is called ______.

misbehaviour of water

anomalous expansion of mercury

anomalous contraction of water

anomalous expansion of water

• ### When water at 00C is heated, its volume goes on decreasing upto _______.

8 degree celcius
10 degree celcius
4 degree celcius
5 degree celcius
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##### what happens when water is more than 4 degree centigrade?

what happen to fish if the water is more than 4 degree centigrade?