William Thomson coined the term thermodynamics in 1749. It is derived from the Greek word term which means heat and “dynamis” which means power. The term made sense as steam engines converted heat into mechanical power and this section of science tried to decipher the conversion of energy, of heat into power.
Thermodynamics has many sections under it and is considered a broad subject because it deals with topics that exist all around us and thus classification becomes necessary.
- Classical Thermodynamics – In this section, the behavior of matter is analyzed with a macroscopic approach. Units such as temperature and pressure are taken into consideration which helps the individuals calculate other properties and to predict the characteristics of the matter that is undergoing the process.
- Statistical Thermodynamics – In this section every molecule is under the spotlight i.e. The properties of each and every molecule and ways in which they interact are taken into consideration to characterize the behavior of a group of molecules.
- Pure Component Thermodynamics – As the name itself states this section tries to describe the behavior of a system that has an unadulterated or pure constituent.
- Solution Thermodynamics – This section attempts to describe the behavior of a system that contains more than one chemical in the mixture.
We will focus on the Classical part of the thermodynamics in our curriculum.
Laws of Thermodynamics
The first and second laws of thermodynamics are essential to know when learning Classical Thermodynamics.
The first law of thermodynamics which is also known as the conservation of energy principle states that energy can neither be created nor destroyed, it can only change form. This law tells us that leaving out nuclear reactions energy cannot be created or destroyed.
The second law of thermodynamics states that Energy in the form of heat only flows from regions of higher temperature to that of lower temperature. Many individuals take this statement lightly and for granted, but it has an extensive impact and consequence.
This is a critical concept for a student trying to study thermodynamics. It forms the basis of the second and third laws of thermodynamics. Simply put, entropy is the measure of the chaos and haphazardness of a system’s molecules.
Imagine there’s a container filled with gas molecules. If the particles stay in a corner and don’t move much it would be a low entropy state as the molecules are highly organized. If the particles move around, as a result filling up the whole container, then the entropy surges.
Different Measures of Energy
Internal Energy: U=intTdS−PdV+sumimuidNi
Helmholtz free energy: F=U−TS
Gibbs Free Energy: G=U+PV−TS
Specific Heat Capacity
Let’s get down to the basics now. As we all know different objects take a different amount of time to heat up, we take power as a constant quantity as it gives the result that some material requires more, and some require less energy to increase their temperature by one kelvin or one-degree centigrade. If we see its real-life application, we’ll notice that a wooden spatula heats up slower than a metal spatula. Thus we arrive at the conclusion that wood is a bad conductor of heat whereas metal is a better conductor of heat. The energy required to raise the temperature of 1kg of a substance by 1K is called its specific heat capacity. The formula for specific heat capacity is
Q = Energy,
m = mass,
c = specific heat capacity and
Delta T = change in temperature