Molar Heat Capacity

Molar heat capacity can be defined as the amount of heat needed to raise the temperature of 1 mole of a substance by one unit & is measured by dividing heat capacity by the total number of moles. It can also be stated as the amount of heat energy that will be required to raise the temperature of a  mass of a substance by 1 unit. The following two things Specific heat capacity & molar heat capacity are the properties derived from the heat capacity of a material.

It is an intensive property, that is, it does not change according to the amount of substance.

Mathematically, we can say that  it is the heat capacity of a substance parted by the number of moles and is expressed as:

Heat Capacity 

Heat capacity or thermal capacity is a physical property of matter, stated as the amount of heat needed to be supplied to an object to induce a unit change in its temperature. The SI unit of the following is joule per kelvin (J/K).

The result of this framework usually varies considerably depending upon the initial temperature of the object and the pressure applied to it.

Variation with Temperature 

It is considerably easy to measure heat capacities as a function of temperature. If we measure the heat capacity with the constant pressure of a pure substance over a wide temperature range The heat capacity comes out to be a smooth and continuous function of temperature except for a smaller number of discontinuities. These discontinuities occur at temperatures where the substance therein undergoes phase changes. It helps us to calculate the enthalpy or entropy change that occurs as we change the values of the temperature of the substance from some reference temperature to any other value. 

Thermodynamics

Before the evolution of thermodynamic laws, heat was considered the measure of an invisible fluid, caloric, that is present in any matter around us. The potential of a substance to hold the fluid was then referred to as the heat capacity of that substance.

Further developments on this changed the whole concept and ideas.

Thermodynamics states that heat is the measure of the total internal energy of a system. In respect of quantifying the heat energy related to matter and its temperature dependence, two properties were defined. These properties were called specific heat capacity and heat capacity of the system.

Thermodynamic Equilibrium 

Thermodynamic equilibrium is the condition of a thermodynamic system, the properties of which do not interchange with time and that can be substituted for another condition only at the expense of effects on other systems. 

It can also be stated as the state of a physical system in which it is in mechanical, chemical, and thermal equilibrium and in which there is, therefore, no tendency for spontaneous change or a sudden change. 

Specific Heat Capacity 

Specific heat is the quantity of heat needed to raise the temperature of 1 gram of a substance by one Celsius degree.

 The equal quantities of different substances needed different amounts of heat to raise them through the same temperature gap, and, from this observation

Specific heat capacity often changes with temperature and is different for each state of matter. The specific heat capacity of a substance may be significantly higher when it is left to expand as it is heated.

This name-specific heat may also mean the ratio between the specific heat capacities of a substance at a given temperature and of a reference substance at a reference temperature.

The Internal Energy of a System 

The internal energy of a thermodynamic system is the energy accommodated within it. It is the energy mandatory to create or prepare the system in any given internal state. It does not incorporate the kinetic energy of motion of the system as a whole, nor the potential energy.

The internal energy is calculated as a difference from a reference zero defined by a standard state.

Its value pivot only on the current state of the system and not on the particular choice from the many possible processes by which energy may pass to or from the system.

The Formula of Molar Heat Capacity 

The numerical can be calculated by simply breaking down their definitions, finding quantities, and substituting them in their respective places in the formulas.

molar heat capacity formula:

         Cm =   C / n 

Cm  =   molar heat capacity 

C     =    heat capacity 

n     =    moles

     n = w / m

It is a very easy way to calculate the molar heat capacity of a substance. 

Application of Heat Capacity 

the handles of utensils are assembled from materials with a high heat capacity to ensure the user’s safety.

The phenomenon of seawater remaining cooler than the surrounding air and sand on a hot summer day, even after being exposed to an equal amount of heat from the sun, can also be explained by the perspective of heat capacity: the high molar heat capacity of water is the reason for many natural events, that includes the Earth’s climate and the survival of aquatic life!

Some Terms related to Molar Capacity 

1.  Change of state 

Changes in state are related to the physical changes in matter. These changes are reversible changes that do not change matter’s chemical composition or chemical properties. For example, when fog converts into water vapour, it is still water and can change back to liquid water again.

2. Heat transfer 

Heat transfer is a process of the function, as opposed to functions of the state; therefore, the quantity of heat transferred in a thermodynamic process that helps to change the state of a system depends on how that process takes place, not only the net difference between the initial and final states of the process. 

3. Thermal stability 

Thermal stability helps us to understand the stability of a water body and its resistance to mixing. It is the amount of work required to transform the water to a uniform water density.

Conclusion 

It is necessary as it will indicate how much energy will be needed to heat or cool an object of a given mass by a given amount. It’s an important material property in so many fields including chemistry and physics.

Engineering disciplines mainly when designing systems where the management of heat is essential. The best application one can see of specific heat is its use in the selection of a suitable cooling medium. 

Cooking utensils are made of metal so they have low specific heat capacity so that it needs less quantity to raise the temperature