Heat capacity, Study notes of Pharmacy

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Electronic education

mustansiriyah university

college of pharmacy

clinical laboratory science dept.

Medical physics

• Name of lecturer:
• Abbas abed lateef
• June 2010 -
• Second course

• Heat capacity or thermal capacity is equal to ratio of heat added to (or removed from) a given mass of material to produce a unit change in temperature. Its unit is Joul per Kelvin (J/K). It is an extensive property; this means that when material increases in size or mass, its heat capacity will increase.
• When dividing heat capacity on mole (the amount of mass), we shall obtain molar heat capacity.

Heat capacity mathematically

• Heat capacity (C) = ΔQ/ΔT --------- (1)
• ; that means, heat capacity C is equal to the change of heat (supplied or removed ) that produce a change in temperature.

• C = 𝑄𝑄2 𝑇𝑇2−𝑇𝑇1^ −𝑄𝑄

• Q 1 = 360J + 500J = 860 J

• i.e. the initial heat or energy was 860j and the final heat is 500 J
• Then the energy of the system was decreased from 860 J to 500J when it is attached to ice.

Specific heat capacity

• Specific heat capacity or specific heat is the heat required to raise one kilogram of mass one kelvin (J/Kg.K).

• Kinetic energy is the motion of molecules inside the system or motion of atoms inside molecule.

Change in internal energy

• The change in internal energy is the magnitude of heat added to or loosed by system at constant pressure and volume.
• From equation (1) and from definition of heat capacity:
• C = ΔQ/ΔT ------(1), for a given mass, equation (1) becomes
• C = ΔQ/n*ΔT ----------------(2) n is the number of moles.

Specific heat capacity

• Specific heat capacity is the amount of heat per unit mass required to raise material one degree of temperature (celecius).