History of the First and Second Laws

History Of the First and Second Laws of Thermodynamics

Modern life would not be the same without two important laws of thermodynamics. Without these two laws we would not have the gasoline engine or electricity in our homes. These two laws made the inventions that we take for granted possible. These two laws are the first and second laws of thermodynamics. The first law of thermodynamics is that energy can neither be created nor destroyed. It forms the basis of the idea that in order to produce a prescribed amount of work, a certain amount of energy must be put into a system. The second law of thermodynamics is about the active nature of systems. It states that systems will work to achieve a state of balance and equilibrium.

The laws of thermodynamics came about through observation. Early scientists simply made observations about the natural world around them and then tried to explain why something happened. Several concepts were important as preliminary observations that led to the laws of thermodynamics. One of the first observations that led to these laws was made by Fahrenheit in 1724 when he noticed that liquids boil at constant temperatures (Crowe, 1998) Benjamin Thompson presented research to the Royal Society in London in 1798 stating that heat is not a substance in itself, but rather that it is produced by the motion of particle (Crowe, 1998).

These laws were the earl building blocks for the laws of thermodynamics.

These discoveries were the beginnings of the first and second laws of thermodynamics, but it was the work of Sadi Carnot and his work with steam engines that gave us its modern form (Crowe, 1998). Carnot's work (1824) centered on the second law of thermodynamics. He showed that the work produced by a steam engine is proportional to the heat transferred from the boiler to the condenser. He proved that heat could only be gained by heat transfer from a warmer to a colder body. Emile Clapeyron (1834) expanded on Carnot's work and devised that "Clapeyron equation," which measured the heat of vaporization of a liquid based on temperature and volume change (Crowe, 1998).

The second law of thermodynamics is easy to observe also. If one places a cup of hot water on a table, soon the heat will disperse from the cup into the surrounding air until equilibrium is established between the temperature of the water and the air. When the water and air reach equilibrium, the transfer of heat stops. This happens when any warmer object is brought in contact with any colder object. This energy transfer can be made to do work as Joule demonstrated.

Joule was the founder of experimental thermodynamics (Nye, 1997). Joule established that different types of energy, mechanical, electrical, and heat can be changed from one form to another. He formulated Joule's law, which states that the heat produced in a wire by an electrical current is proportional to the product of the resistance of the wire and the square of the current. Joule proved his theory by comparing the water temperature at the top of a waterfall with temperatures at the bottom of a waterfall. As predicted, the temperatures at the bottom were greater than those at the top. The energy of falling water did indeed produce heat (Nye, 1997)