C v represents the molar heat capacity C when the volume is constant. In other words, C v is the heat energy transfer between a system and its surroundings without any change in the volume of that system. Where Cp represents the specific heat at constant pressure dH is the change in enthalpy dT is the change in temperature.ĭuring a small change in the temperature of a substance, C v is the amount of heat energy absorbed/released per unit mass of a substance where volume does not change. The system absorbs or releases heat without the change in pressure in that substance, then its specific heat at constant pressure, C p can be written as: When a liquid changes to its gaseous form (i.e., the change from water to water vapour), the enthalpy change is called heat vaporisation. Furthermore, enthalpy change occurs during the change of phase or state of a substance.įor example, when a solid changes to its liquid form (i.e., the change from ice to water), the enthalpy change is called the heat of fusion. The change in temperature will always cause a change in the enthalpy of the system.Įnthalpy (∆H) is the heat energy absorbed or released by the system. So, C p represents the molar heat capacity, C when pressure is constant. In other words, under constant pressure, it is the heat energy transfer between a system and its surroundings. In a system, C p is the amount of heat energy released or absorbed by a unit mass of the substance with the change in temperature at a constant pressure. The constant C is known as the molar heat capacity of the body of the given substance. Q is the heat supplied or needed to bring about a change in temperature (∆T) in 1 mole of any given substance, It also significantly depends on the nature, size and composition of a substance in a system. The total amount of energy in the form of heat needed to increase the temperature of 1 mole of any substance by 1 unit is called the molar heat capacity (C) of that substance. What are Heat Capacity C, C p, and C v ? Therefore, the temperature change in a body is directly proportional to the heat transferred to the given body. Heat capacity is the ratio of heat absorbed by a material to the temperature change. The calorie is defined by the specific heat of water, which is defined as one calorie per degree Celsius.

Specific heat is the heat capacity in calories per gram. In terms of the actual amount of material being considered, most frequently a mole, it is usually stated as calories per degree (the molecular weight in grams). The ratio of heat absorbed by a substance to the temperature change is known as heat capacity.

Absolute entropy from cp