Why is delta s negative

Entropy change. Gibbs free energy. At what temperature will the reaction above become spontaneous? The fact that both terms are negative means that the Gibbs free energy equation is balanced and temperature dependent:. Because this reaction has a positive Delta G it will be non-spontaneous as written. CO 2 g CH 3 OH l COCl 2 g Re: Negative delta s value Post by Harrison Wang 1H » Fri Feb 02, am Negative delta s does not by itself correspond to a spontaneous process, but rather the product of T and delta S should be less than delta H, which has to be negative.

Negative delta S actually means that either temperature has decreased, pressure has increased, or volume has decreased. Re: Negative delta s value Post by Leah Savage 2F » Fri Feb 02, am If you think of the idea of a spontaneous process, it would make sense that it would often correspond to a positive entropy. The universe always wants to be more disordered and be going to less energy, so this would make a positive delta S and a negative delta H.

Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. One person asked if this implied negative entropy, but I don't see how this could be possible.

For physical processes the entropy of the universe still goes up but within the confines of the system being studied entropy decreases. One example is a freezer with a cup of liquid water in it. The freezer will utilize the electrical energy coming in to pump heat from the water until it becomes a solid ice. At which point the entropy of the system the contents of the freezer decreases, however the electrical energy needed to be produced to power the freezer such as coal burning a solid to a gas and heat was wasted by the freezer in the process both of which create larger amounts of entropy than was reduced in the system by the freezer.

For chemical processes entropy can be a great driver of many reactions but it is not absolute. A system's favorability to release energy enthalpy competes with entropy. For example, an electron of hydrogen may have higher entropy if it drifts from the core proton but the electrostatic forces and quantum mechanics energetically keep it bound to the atom.

For isobaric processes, you much determine the change in Gibbs free energy for the reaction to know which way it is driven. For isochoric processes, you must determine the Helmholtz free energy to know which way a reaction is driven.

One example is the oxidation of iron in air. When the oxygen is in the gas state it has higher entropy but the energy of bonding with iron is so great that at normal pressures oxygen goes from the gas phase and the iron rusts "enthalpy wins" as delta G is negative.

Now we must consider statistical thermodynamics, this process is pressure dependent. At normal atmospheric pressure, the forward rate of oxygen entering the gas phase is the same as the reverse process.