Here liquids are subjected to a special state called super cooling and it is the state where liquid doesn’t solidify even if it is below the freezing point. Liquids needs something become solid at a certain temperature because there is a process which involves the lineup of molecules. All states of matter solid, liquid, or gas at constant pressure depends on its energy or heat. In a gas, molecules are warmer, and are higher in energy. They move a lot, fly everywhere and collide with each other often. But in a liquid, molecules don’t have as much energy as compared to gas and move around slow enough to form a bonds between them, keeping them close together. At lower temperatures, where molecules have the least amount of energy, they forma solid. They’re still vibrating a bit, but at this point the bonds between them keep the molecules rigidly in place.

In order to freeze water, it should have low energy meaning it should be cold and it should form intermolecular bonds holding it as a solid. To make this bond water has to form a nucleus around which the cool water will for ice eventually. This point is called nucleation site it is the place where structure of ice crystal begins to form. This then allows other water molecules around it to form bonds eventually expanding to make one solid piece of ice. This nucleation sites needs to be created and this creation of nucleation is generally helped by impurities in water. This impurities might be a mineral present in water. Nucleation site can also be created by disturbing the super cooled liquid like shaking. As the very cold water moves around cool molecules will and start the process of turning into ice. So to create super cool water, you have to keep impurities and movement as far as possible.

How to supercool water

To make super cool water you need a freezer and a bottle of standard drugstore-brand purified water. Mineral water is useless as it contains things that will act as a nucleation sites. Keep your bottle of water in the freezer. Keep it in the freezer for about two and a half hours and make sure that you don’t open the freezer because we want gradual cooling and opening the freezer might disturb and gradual cooling process. If everything went well, you will have a supercooled below-freezing liquid water. If you slam this bottle of supercooled water against the table, you will create a nucleation site, and you can actually see the ice crystal form almost instantly. Which is SUPER COOL!

During the day time, when the heat radiation from the sun comes towards the earth, they are reflected back into space by the earth’s atmosphere. As a result, only some amount of heat radiation is able to reach the earth. During the night, the earth radiates heat which is reflected back to the surface by the atmosphere. It is therefore, if there were no atmosphere, all of the heat radiation from the sun would reach Earth and the Earth would be inhospitably hot in the day time. On the other hand, all of the heat radiated by the earth in the night time would escape into the space thus leaving the earth inhospitably cold.

Anomalous expansion of water

Unlike other liquids, water shows unusual expansion which is called anomalous expansion of water. When temperature of water decreases from 100 C, volume of the water also decreases and hence the density increases. The volume of water becomes minimum at 4 C. If the temperature is further reduced to zero, the volume of water again expands. In further cooling from 0 C, ice contracts normally. Thus the water has maximum density at 4 C.

Small space is left between two rails on a railway track

The rail may be heated due to (i) the high temperature on summer and (ii) the heat caused by the friction between the wheels and the track. Due to these heating, the rails get expanded and enough space is to be left for the expansion of the rails, otherwise the railway track may be curved during expansion and may be displaced from the original track. Hence, the spaces are left between the rails of a railway track.

Mercury is used as a thermometric substance

Mercury has uniform expansion and it does not wet the glass tube. Therefore, mercury is mostly used as the thermometric substance.

Blankets can be used to protect the Ice from Melting

A blanket traps a large amount of air between its fibers. When we cover our body with the blanket, the trapped air prevents the heat transmission from our body to the cold surrounding. As a result, we feel warm. Similarly, when we cover the ice with the blanket, the trapped air of the blanket prevents the heat from outside surrounding to flow into the cold ice. As a result the ice gain no heat and hence remains frozen.

Animal curl into a ball during Winter

We know that the amount of heat radiated by a body is directly proportional to the surface area. If the surface area is reduced, heat radiated is also reduced. For a given volume, the surface area is minimum when it is a sphere. Hence, to reduce the heat radiation from their bodies by reducing the surface area, the animals curl into a ball in the winter.