It has been found that the burns caused by steam are much more severe than those caused by boiling water though both of them are at the same temperature of 100 °C. This is due to the fact that steam contains more heat, in the form of latent heat, than boiling water.
The changing of a solid directly into vapours on heating and of vapours into solid on cooling, is known as
Test your Knowlegde
Fill in the blanks
1)the movement of particles is the __________________ in solids, more in liquids and the maximum in gases.
2) The spreading out and mixing of a substance with another substance due to the motion of its particles is called ________________
3) Diffusion is the __________________ of matter which is based on the motion of its particles.
4) Diffsion is fastest in ______ and slowest in _____
5) The rate of diffusion increases on increasing the __________________ of the diffusing substance.
6) The rate of diffusion of a gas depends on its __________________.
7) The ________ and oxygen gas present in air diffuse into water, and dissolve in it.
8) The aquatic plants use the dissolved carbon dioxide for preparing __________________ by photosynthesis and aquatic animals use the dissolved oxygen of water for breathing.
9) The process in which a solid substance converts into a liquid on heating,is called ___________
10) The temperature at which a solid substance melts and changes into a liq uid at atmospheric pressure,is called __________________.
11)Higher the melting point of a solid substance, greater will be the __________________ of attraction between its particles.
12) At the melting point, the particles of a solid have sufficient kinetic __________________ to overcome the strong forces of attraction holding them in fixed positions and break to form small groups of particles and the solid melts to form aliquid.
13) The process in which a liquid substance changes into a gas rapidly on heating, is called _________
14) The process of changing a __________________ (or vapour) to a liquid by cooling is called condensation.
15) The process of changing a __________________ into a solid by cooling is called freezing.
16) Latent heat does not raise (or increase) the __________________.
17) The __________________ of a solid is the quantity of heat in joules required to convert 1 kilogram of the solid (at its melting point) to liquid, without any change in temperature.
18) The latent heat of fusion of ice is _____ joules per kilogram
19) The __________________ of a liquid is the quantity of heat in joules required to convert 1 kilogram of the liquid (at its boiling point) to vapour or gas, without any change in temperature.
20) The latent heat of vaporization of water is __________ joules per kilogram
21) The changing of a solid directly into vapours on heating and of vapours into solid on cooling, is known as __________________.
22) The three common substances which undergo sublimation are: ______,______ and _______
23) When these solids are heated, their particles move so quickly that they separate completely to form __________________ (or gas).
24) And when these vapor (or __________________) is cooled, these particles slow down so quickly that they become fixed and form a solid.