What walk it average when over there is a negative delta $S$ $(-Delta S)$? One human asked if this implied an unfavorable entropy, yet I don"t see how this can be possible.

You are watching: What does delta s stand for

Does this indicate a an unfavorable change in entropy? If the former, exactly how can an unfavorable entropy exist?


Negative delta S ($Delta S ) is a diminish in entropy in regard to the system.

For physical processes the entropy that the world still walk up but within the confines of the system being studied entropy decreases.

One instance is a freezer v a cup of liquid water in it. The freezer will make use of the electric energy coming in to pump heat from the water until it becomes a heavy (ice). In ~ which suggest the entropy the the system (the materials of the freezer) decreases, however the electrical energy required to be developed to power the freezer such together coal (burning a solid come a gas) and heat was wasted by the freezer in the process both of which create larger amounts of entropy than was decreased in the device by the freezer.

For chemical processes entropy have the right to be a an excellent driver of many reactions however it is not absolute. A system"s favorability to release energy (enthalpy) competes v entropy. For example, an electron of hydrogen may have higher entropy if the drifts native the core proton however the electrostatic pressures (and quantum mechanics) energetically keep it bound to the atom. Because that isobaric processes, you much determine the readjust in Gibbs cost-free energy for the reaction to recognize which means it is driven. Because that isochoric processes, friend must identify the Helmholtz totally free energy to understand which method a reaction is driven.

See more: Taylor Lautner My Wife And Kids, What Happened To Taylor Lautner

One instance is the oxidation of iron in air. As soon as the oxygen is in the gas state it has greater entropy however the energy of bonding through iron is so good that at typical pressures oxygen goes native the gas phase and also the steel rusts ("enthalpy wins") as delta G is negative.

Now us must think about statistical thermodynamics, this process is press dependent. At normal atmospheric pressure, the forward rate of oxygen start the gas phase is the same as the turning back process. If the steel oxide were hosted in a saturated high vacuum the reverse process would occur and also the iron oxide would certainly reduce back to stole like numerous asteroids ("entropy wins"; note: thermodynamics is equilibrium after an limitless time). Accountancy for pressure modifies the Gibbs cost-free energy equation to: $$Delta G = Delta G^circ -RT ln(P) = Delta H^circ -TDelta S^circ -RT ln(P)$$

One thing to note is that for chemical reactions the entropy and also enthalpy values are for a typical temperature (such together $298 extK$). Because that a spontaneous mechanism with $Delta S^circ enthalpy need to be negative, this warmth in fact is absorbed by the mechanism or the environment and produces entropy follow to: $$ int mathrm dS equiv int fracC_vT,mathrm dT equiv int fracmathrm dQT $$

This in and of itself produces some entropy in the cosmos though may not net above zero as the bonding power is quiet the major driving force.