Thermodynamics is the study of energy, the conversion of energy to various forms and the ability of energy to do work. The term ‘Thermodynamics’ originate from two root words ‘thermo’which means heat and ‘dynamic’which means power. The laws of thermodynamics are absolute and the observable universe obeys the Laws of Thermodynamics. The First Law of Thermodynamics is commonly known as the Law of Conservation of Matter, states that matter or energy cannot be created nor destroyed. It means the quantity of matter or energy remains the same. Mattercan change its state from solid state to liquid, liquid to gas, gas to plasma or back again. Stillthe total amount of matter or energy in the universe remains constant.If we take an example of a machine, the total energy output from the machine is equal to the heat supplied. In real world applications of the first law we can see some energy always escapes into the outside world, thus leading to inefficiency. This escape can be explained using The Second Law of Thermodynamics.
The Second Law of Thermodynamics is otherwise known as the Law of Increased Entropy. ‘Entropy’ is defined as quantity of unusable energy within a closed or isolated system. According to this law, thequality of matter or energy depreciatesslowly over time. Usable energy is used for some form of output, growth and repair. In all these process of conversion of usable energy into unusable energy, usable energy is irretrievably lost in the form of unusable energy. Energy differs in its quality or ability to do useful work. Energy must move or flow from a level of high-quality energy to a level of lower-quality energy in the process of a useful work.
The Second Law of Thermodynamics implies that high-quality energy can never be used over again. Matter can be recycled but high-quality energy can never be recycled.
Fuels and foods can be used only once to carry out useful work. Once a piece of coal or a barrel of oil is burned, its high-quality potential energy is lost forever. This also implies that the high-quality energy available from fossil fuels, uranium, or any concentrated energy source is less than assumed by the first energy law. In an internal combustion automobile engine, about 4/5thof the chemical energy is degraded to low quality heat which is released to the environment. In the remaining 1/5th of high – quality energy, 50 % is degraded to low-quality heat energy through friction. In short only 10% of the high-quality chemical energy available in the gasoline is converted to mechanical energy used to drive the car.The chemical potential energy concentrated in coal or a tank of gasoline and the concentrated heat energy at a high temperature are forms of high-quality energy. They have the capability to carry out useful work in moving or changing matter. Less concentrated heat energy at a low temperature has little remaining ability to perform useful work and is an example of low- quality energy.
In brief, The First Law of Thermodynamics deals with the quantity of energy available from an energy conversion process, whereas the second energy law deals with the quality of energy available.
References
Matter and Energy Laws: A Primer. Retrieved on December 30, 2010 from
Second Law of Thermodynamics. Retrieved on December 30, 2010 from
Three Laws of Thermodynamics.Retrieved on December 30, 2010 from