1. Heat is the form of energy.
2. “Temperature and Heat” to describe the hot and cold.
3. The state of thermal equilibrium denotes a state of a body where it neither receives nor gives out heat
energy.
4. Heat is the energy that flows from a hotter to a colder body.
5. The SI unit of heat is Joule (J) and CGS unit is calorie (cal).
6. The amount of heat required to increase the temperature of 1gram of water by 10C is called calorie.
7. 1Cal = 4.186 joules
8. The SI unit of temperature is Kelvin (K). It can also be expressed as degree Celsius (0C).
9. 0 0C = 273K.
10. The temperature in Kelvin = 273+Temperature in degree Celsius.
11. Temperature measured in Kelvin scale is called absolute temperature.
12. The bodies possess kinetic energy when they are in motion.
13. We know the rise in temperature depends on the nature of the material.
14.The average kinetic energy of the molecules is directly proportional to the absolute temperature.
15.Temperature is a quantity that denotes which body is hotter and which is colder.
16. “Specific heat” of substance, S =
. J/Kg-K.
17. Specific heat gives us an idea of the degree of ‘reluctance’ of a substance to change its temperature.
18. CGS unit of specific heat is cal/g-oC and SI unit of it is J / kg – K.
19. 1 cal/g- oC = 1 kcal /kg-K= 4.2 x 103J/kg-K
20. The oceans behave like heat “store houses” for the earth.
21. Oceans can absorb large amounts of heat at the equator without much rise in temperature due to high
specific heat capacity of water.
22. Water has greater specific heat value.
23. Net heat lost= Net heat gain. This is known as principle of method of mixtures.
24. “The process of escaping of molecules from the surface of a liquid at any temperature is called
evaporation”
25. Evaporation is a surface phenomenon.
26. “The change of phase from liquid to gas that occurs at the surface of the liquid”.This process is
called evoparation.
27. The phase change from gas to liquid”.This process is called Condensation.
28. ‘Condensation’ is a warming process.
29. Evaporation is a cooling process.
30. The amount of water vapor present in air is called the humidity of air.
31. The water droplets condensed on such surface are known as dew.
32. The thick mist is called fog.
33. The boiling point of water is 1000C.
34. Consider a liquid of mass ‘m’ requires heat energy ‘Q’ calories to change from its state liquid phase
to gas phase. Then Latent heat of vaporization is Q/m.
35. CGS unit and SI unit of latent heat of vaporization is Cal/gm. and J/kg respectively.
36. The boiling point of water at constant atmospheric pressure (1atm) is 100°C or 373K .
37. Latent heat of vaporization of water is 540 Cal/gm.
38. When water or any liquid is heated, the solubility of gases it contains reduces.
39. This process of converting solid into a liquid is called “Melting”.
40. Ice becomes to water .This process takes place at a constant temperature 0°C or 273K.
41. Ice becomes to water at 00C. This temperature is called melting point.
42. The Heat energy required to convert 1gm of solid completely into liquid at a constant temperature is called
Latent heat of fusion.
43. Latent heat of fusion L = Q/m.
44. The value of Latent heat of fusion of ice is 80cal/gm.
45. “The process in which the substance in liquid phase changes to solid phase by losing some energy is
called freezing.”
46. If two different systems, A and B, (thermal contact) are in thermal equilibrium individually with another
system C. then the systems A and B are in thermal equilibrium with each other.
47. The specific heat capacity of a material is the amount of heat required to raise the temperature of
unit mass of the material by or unit.
48. Condensation is the reverse process of evaporation.
49. The Specific heat of a Lead is 0.031 Cal/g-oC. (or) 130 J/kg-K.
50. The Specific heat of a Water is 1 Cal/g-oC 4180 J/kg-K.
