= 120m . We can - - - - Unit Heat and thermodynamics The term heat capacity or specific heat capacity does not mean that object contains a certain amount of heat. Heat is energy transfer from the object at higher temperature to the object at lower temperature. The correct usage is ‘internal energy capacity’.
But for historical reason the term ‘heat capacity’ or ‘specific heat capacity’ are retained. Note When two objects of same mass are heated at equal rates, the object with smaller specific heat capacity will have a faster temperature increase. When two objects of same mass are left to cool down , the temperature of the object with smaller specific heat capacity will drop faster. When we study properties of gases, it is more practical to use molar specific heat capacity.
Molar specific heat capacity is defined as heat energy required to increase the temperature of one mole of substance by 1K or °C. It can be written as follows C = µ ∆ ∆ Q Here C is known as molar specific heat capacity of a substance and μ is number of moles in the substance. The SI unit for molar specific heat capacity is J mol – K – . It is also a positive quantity.
∆Q = m s∆T Therefore, s = ∆ ∆ Q Where s is known as specific heat capacity of a substance and its value depends only on the nature of the substance not amount of substance ΔQ = Amount of heat energy ΔT = Change in temperature m = Mass of the substance The SI unit for specific heat capacity is J kg – K – . Heat capacity and specific heat capacity are always positive quantities. Table . Specific heat capacity of some common substances at atm ( °C) Material Specific heat capacity (Jkg −l K − ) Air Lead Copper Iron (steel) Glass Aluminium Human body Water From the table .
it is clear that water