The purpose is to determine the available energy. Some of the energy in any system is useless - can't be converted into useful work.
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The Bee Gees or Brothers Gibbs were all born in Douglas, the largest town on the Isle of Man and the main port of entry. Barry Alan Crompton Gibb was born on September 1, 1946, and the twins Robin Hugh Gibb and Maurice Ernest Gibb on December 22, 1949. On December 28, 1957, the brothers and two friends performed live before the public for the first time at a local Gaumont cinema. The last of the Gibb children, Andrew Roy Gibb, was born March 5, 1958, in Manchester. He would later record and perform as Andy Gibb.
Since the question seems to be about reactions - and the whole idea of a reaction is that something is changing... The CHANGE in Gibbs free energy will always be positive for a spontaneous reaction. As far as whether the Gibbs free energy of a system (without the term "change" attached) ... Since Gibbs free energy is a state function, it is always defined relative to a standard state. Asking if the Gibbs free energy is positive is akin to asking how "high" something is - the answer depends on where you define zero to be. If you define 0 height to be the level of the ground you are standing on, you will get a different answer than if you define zero height to be "sea level". A cactus in Death Valley may have a positive height relative to the ground, but would actually have a negative height relative to sea level. Likewise, the Gibbs free energy of a system will be positive or negative (or zero) depending on what you define as the standard state.
The Gibbs free energy will always be negative for a spontaneous reaction at constant temperature and pressure. This suggests that the reaction is thermodynamically favorable and can proceed without the input of external energy.
Since the question seems to be about reactions - and the whole idea of a reaction is that something is changing... The CHANGE in Gibbs free energy will always be positive for a spontaneous reaction. As far as whether the Gibbs free energy of a system (without the term "change" attached) ... Since Gibbs free energy is a state function, it is always defined relative to a standard state. Asking if the Gibbs free energy is positive is akin to asking how "high" something is - the answer depends on where you define zero to be. If you define 0 height to be the level of the ground you are standing on, you will get a different answer than if you define zero height to be "sea level". A cactus in Death Valley may have a positive height relative to the ground, but would actually have a negative height relative to sea level. Likewise, the Gibbs free energy of a system will be positive or negative (or zero) depending on what you define as the standard state.
when H is negative and S is positive
Gibbs energy accounts for both enthalpy (heat) and entropy (disorder) in a system. A reaction will be spontaneous if the Gibbs energy change is negative, which occurs when enthalpy is negative (exothermic) and/or entropy is positive (increased disorder). The relationship between Gibbs energy, enthalpy, and entropy is described by the equation ΔG = ΔH - TΔS, where T is temperature in Kelvin.
When H is positive and S is negative
Photosynthesis is a positive delta G as it produces more free energy than it uses. The overall result of the Gibbs equations shows that delta G is positive
The name of the single thermodynamic quantity is Gibbs free energy (G). The symbol for Gibbs free energy is ΔG (delta G). The sign of ΔG determines whether a reaction is spontaneous (negative ΔG) or non-spontaneous (positive ΔG).
Guys watch out the question, if your question end with positive then the answer will be An endothermic reaction that decreases in entropy. If the question end with negative then its An exothermic reaction that increases in entropy--APEX hope this help
An endergonic reaction is a reaction in which the change in Gibbs free energy is positive, indicating that the reaction requires an input of energy to proceed. This means that the products of the reaction have more free energy than the reactants.
Whether or not a chemical process is spontaneous is determined by a variable named the Gibbs' free energy, or just Gibbs' energy, given by the formula G = H - TS, where G is the Gibbs' energy, H is enthalpy, T is temperature and S is entropy. A negative G implies that the chemical process is spontaneous and will occur by itself, and a positive G implies that energy is required to make the reaction occur.
A negative Gibbs free-energy value indicates that a reaction is spontaneous, meaning it can proceed without requiring external energy input. It suggests that the products of the reaction are more stable than the reactants at the given conditions.