Specific heat capacity

Hello students, we know that when heat is given to substance, its temperature gets increased. To increase the temperature of substance by particular extent, certain specific amount of heat is required. Here we are going to study the parameters on which the heat is depends to raise the temperature of substance.

Let’s understand concept of Specific heat capacity in details….!

To understand the concept of specific heat capacity consider the following cases

Case.1 Suppose that 2 ltr water is filled in beaker 1 and 4 ltr water is filled in beaker 2 at same initial temperature i.e. at room temperature shown below,

Now we want to increase the temperature of water in both beakers to 500 C from its initial temperature of 250 C . For this we have provided heat to both of them. Then the question arises here that the heat needed for both beakers is same or not? Definitely here we can conclude that heat need to raise the temperature of water in beaker 2 will be more than that of beaker 1. Hence we can say that,

Heat (Q) required to raise the temperature of substance is directly proportional to the mass of substance (m),

∴ Q α m………….(1)

Case.2 Suppose that 2 ltr water is filled in beaker in two different temperature conditions as shown below,

Now we want to increase the temperature of water in both beakers to 500 C from its initial temperatures of  100 C & 300 C repectively. Here also we have to provide heat to both of them. Then again the question arises here that the heat needed for both beakers is same or not? Definitely here we can conclude that heat need to raise the temperature of water in beaker 100 C will be more than that of beaker 300 C. Hence we can say that,

Heat (Q) required to raise the temperature of substance is directly proportional to the difference of temperature of substance and surrounding (∆θ),

∴Q α  ∆θ………….(2)

Then from both cases we can write that,

∴Q α  m.∆θ

∴Q=c m.∆θ………….(3)

Where ‘c’  is constant of proportionality known as specific heat capacity.

∴c=Q/(m.∆θ)

Hence “the specific heat capacity is defined as the amount of heat per unit mass absorbed/emitted by the substance per unit change its temperature.”

The simplest form of definition can be as, ‘the amount of heat required to raise the temperature of substance by 10 C or 10 K is called as specific heat capacity.’

• It depends on the nature of the substance and its temperature.
• The SI unit of specific heat capacity is J kg–1 K–1 .

Some important terms related to gases…..!

• Specific heat capacity of gas at constant pressure:

The amount of heat required raising the temperature of one mole of gas by 10 C or 10 K keeping its pressure constant is called as specific heat capacity at constant pressure and is denoted by CP.

• Specific heat capacity of gas at constant volume:

The amount of heat required raising the temperature of one mole of gas by 10 C or 10 K keeping its volume constant is called as specific heat capacity at constant pressure and is denoted by CV.

Updated: January 7, 2022 — 2:30 am