2016 Jan

Laws of Thermodynamics

January 1, 2016

Laws of Thermodynamics

Thermodynamics is a branch of physics that focuses on heat, work, energy and their interactions within a body, also within its immediate environment. It also concerns the conversion of thermal energy into other forms of energy, and is mostly applied in the field of physical chemistry. The science of thermodynamics is often an important part of geological, chemical, biochemical, engineering, and medical concepts. To fully understand the fundamentals of its importance, let’s delve into the history, types, and laws of thermodynamics.

It is generally accepted that the study of thermodynamics, as a scientific field, started in 1650 when Otto von Guericke built the first vacuum pump. Thereafter, Robert Hooke and Robert Boyle built an air pump and noticed a relationship between pressure, temperature and volume. Together, they formulated the popular equation known as Boyle’s Law. This describes gases with constant temperatures, stating that their pressure and volume values are inversely proportionate to each other. This eventually led to the building of the first engine, by Thomas Savery – which consequently started the science of modern thermodynamics; having a huge impact on the industrial revolution.

Since thermodynamics is such an extensive scientific field, there are several important concepts which are taught in physics tuition classes, school and in university. Specific heat, entropy, and heat transfer are some of the concepts that will be briefly discussed, along with the four laws of thermodynamics.

Specific heat is defined as the amount of heat needed to increase the temperature of a certain substance by one unit of mass (often gram) by 1 oC. For example, the specific heat of water is 4.186 Joule per gram per oC. Specific heat values are necessary to determine how much heat should be added to a system to obtain a correct the correct results or products.

Entropy is a measure of disorder that concerns the loss of heat in a closed system. A high entropy value can be interpreted as the amount of heat that is no longer available in the closed system, whereas a low entropy value means there is either a high value of heat or a lesser extent of thermal energy loss.

Heat transfer is simply the amount of heat transferred from one substance (or system) to another, or to its environment. Conduction, convection, radiation, and advection are all types of heat transfer.

There are four laws of thermodynamics (in simple terms), which explain the basic rules that thermodynamic systems follow:

1. The Zeroth Law: If two systems, or bodies, are in thermodynamic equilibrium with a third, then the first two will be in equilibrium as well.

2. The First Law: Heat is a form of energy – hence the conservation of energy laws apply. For example, energy cannot be created or destroyed. During our Physics tuition classes, it is taught that the increase in internal energy is the sum of the heat absorbed by the system and the work done on the system.

3. The Second Law: Heat cannot be transferred from a system of lower temperature to a system of higher temperature without the addition of energy.

4. The Third Law: The entropy value of a perfect crystalline structure at absolute zero (-273.15 oC) is equal to zero.

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