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The Question & Answer (Q&A) Knowledge Managenet

The Internet has many places to ask questions about anything imaginable and find past answers on almost everything.

Table of Contents

- How does energy become unusable?
- Which case change in entropy is negative?
- Will energy ever run out?
- Can entropy be reversed?
- What happens if entropy is reversed?
- What is entropy in time?
- Is it possible for the entropy change of a closed system to be zero?
- How is the second law expressed?
- Does increasing volume increase entropy?
- Does entropy increase with decrease in volume?
- Is entropy extensive or intensive?
- How do you calculate change in entropy?

Energy cannot be created or destroyed, but it can change from more-useful forms into less-useful forms. As it turns out, in every real-world energy transfer or transformation, some amount of energy is converted to a form that’s unusable (unavailable to do work).

sublimation of solid to gas.

The truth is, any of the fossil fuels that are usually in the discussion, like oil and natural gas, probably won’t be running out for generations, if ever. Some resources are able to be recycled, and others can be recovered. So as our reserves dwindle down, they’ll just start becoming more expensive to produce.

Entropy in closed systems cannot be reversed globally with overwhelming probability, but it can be reversed locally as long as it is possible to put the entropy somewhere else. “the second law of thermodynamics says that entropy always increases with time.”

There are more ways for random energy to enter the system, than there are for a very specific form of energy to enter the system to maintain the ordered (lower entropy) state. You can never win. Reversing entropy would mean going back in time, so a short answer, no. However if you mean decreasing then you could.

As one goes “forward” in time, the second law of thermodynamics says, the entropy of an isolated system can increase, but not decrease. Thus, entropy measurement is a way of distinguishing the past from the future.

Entropy can be transferred to or from a system in two forms: heat transfer and mass flow. Thus, the entropy transfer for an adiabatic closed system is zero.

The second law can be expressed in several ways, the simplest being that heat will naturally flow from a hotter to a colder body. At its heart is a property of thermodynamic systems called entropy – in the equations above it is represented by “S” – in loose terms, a measure of the amount of disorder within a system.

Changes in volume will lead to changes in entropy. The larger the volume the more ways there are to distribute the molecules in that volume; the more ways there are to distribute the molecules (energy), the higher the entropy. An increase in volume will increase the entropy.

Like freedom, the entropy of a system increases with the temperature and with volume. For a certain number of atoms or molecules, an increase in volume results in a decrease in concentration. Therefore, the entropy of a system increases as the concentrations of the components decrease.

Intensive Entropy? Entropy in classical thermodynamics [1] is an extensive quantity, which like energy, volume, or particle number, is additive when systems in equivalent thermody- namic states are aggregated.

Since each reservoir undergoes an internally reversible, isothermal process, the entropy change for each reservoir can be determined from ΔS = Q/T where T is the constant absolute temperature of the system and Q is the heat transfer for the internally reversible process.