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Standard entropy measures the amount of heat energy in a closed system that is unavailable for work and increases over time. It is expressed as S° in joules per mole of Kelvin temperature. The laws of thermodynamics state that energy cannot be created or destroyed, and statistical mechanics is used to calculate energy transfer. The illusion that standard entropy is decreasing on Earth is due to Earth not being a closed system, and highly structured chemicals like diamond have a lower standard entropy state due to the natural energy and pressure expended in their production.
Standard entropy, in general, is a measure of the amount of heat energy in a closed system that is unavailable for work, and is usually thought of as the amount of disorder a system contains. The definition of standard entropy has slightly different meanings depending on the field of science to which it is applied. In chemistry, standard molar entropy is defined as the entropy of 1 mole, or gram molecule, of matter at a standard atmospheric pressure of 14.7 pounds/inch2 (101.3 kPa) and a given temperature.
Physical systems in nature are assumed to be undergoing a standard entropy change. This results in increasing levels of standard entropy as time progresses, with the end result being that the universe will someday encounter maximum entropy. Known as heat death, it is a state in which all energy is equally distributed in space and at the same temperature, making it unable to do any work.
The symbol used to represent standard entropy is S° and it is expressed in units of work or energy known as joules, per mole of Kelvin temperature, such that the standard molar entropy would be Sm°/J mole-1 K- 1. This is broken down into a unitless number in a standard entropy table. The most durable of substances has the lowest intrinsic entropy, where diamond at a standard temperature of 77° Fahrenheit (25° Celsius or 298 Kelvin) has the lowest known entropy of 2.377, with liquid water 69.9 and the helium of 126.
The laws of thermodynamics state that energy cannot be created or destroyed. The calculation of standard entropy, therefore, is a method for determining the movement of energy between matter and systems, where the net energy of the entire universe, considered as a closed system, always remains constant. Statistical mechanics is often used to calculate this energy transfer in chemistry and physics, as it can model the motion of molecules in various energy states.
Although entropy is said to be increasing overall in space, the illusion in human activity is that it is decreasing. When matter is transformed into something useful for work, the standard entropy or disorder of the chemical state of the raw material used is reduced. However, much more stranded energy is used in the production of the product than it is worth.
This illusion that standard entropy is shrinking on Earth as civilization brings order out of chaos is perpetuated by the fact that Earth is not a closed system. As highly structured chemicals such as refined fossil fuels are burned, more net heat energy is lost to space in the same way that the sun radiates most of its heat into space. This heat can never be recovered.
This is why materials like diamond have a lower standard entropy state at 2.377 than graphite at 5.74, although both are composed of the same element, carbon. Much more natural energy and pressure was expended in the production of diamond than graphite, giving it a higher level of intrinsic order. Thus, the higher the order of a system or material, the more standard entropy has contributed to the universe in its production.
