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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.
when H is negative and S is positive
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.
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.
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
Exothermic, because the reaction enthalpy must be negative. With polymerization, the entropy decreases. The Gibbs energy has to be negative. Thus negative reaction enthalpy. Gibbs energy = reaction enthalpy - temperature*entropy
Spontaneous reaction
Positive (greater than 0).
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.
True, a large positive value of entropy tends to favor products of a chemical reaction. However, entropy can be offset by enthalpy; a large positive value of enthalpy tends to favor the reactants of a chemical reaction. The true measure to determine which side of a chemical reaction is favored is the change in Gibbs' free energy, which accounts for both entropy and enthalpy, as calculated by: Change in Gibbs = Change in Enthalpy - Temp in Kelvin * Change in Entropy A negative value of Gibbs free energy will always favour the products of a chemical reaction.
Yes, as long as the entropy of the universe increases.
Gibbs free energy -- symbol G. If the change in Gibbs free energy for a reaction is negative, the reaction is spontaneous. If it is zero, you are at equilibrium. If it is positive, the reaction is NOT spontaneous.G ≡ H -TS (or in another useful form dG = dH -TdS)whereH is enthalpyT is absolute temperatureS is entropy
An endergonic reaction is a chemical reaction in which the standard change in free energy is positive.