150
Fundamentally, because the Gibbs free energy of elemental hydrogen and oxygen is substantially greater than the Gibbs free energy of the water formed by their chemical reaction, and the activation energy for the reaction is not excessively high.
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
It tells if the reaction will process spontaneously or not
S > 0 contributes to spontaneity.
Fundamentally, because the Gibbs free energy of elemental hydrogen and oxygen is substantially greater than the Gibbs free energy of the water formed by their chemical reaction, and the activation energy for the reaction is not excessively high.
It predicts whether or not a reaction will be spontaneous.
it depends on the entropy and enathalpy of the reaction
Spontaneous reaction
it depends on the entropy and enathalpy of the reaction
If G < 0, the reaction is spontaneous.
Positive (greater than 0).
Gibbs free energy represents the maximum reversible work that can be extracted from a system at constant temperature and pressure. It combines the system's enthalpy and entropy to predict whether a reaction is spontaneous. The change in Gibbs free energy (∆G) determines whether a reaction will proceed spontaneously or not.
B
When the Gibbs free energy for a reaction is greater than zero, the reaction is "disfavored" - won't proceed in that direction - in fact it may try go in the reverse direction if possible. When the Gibbs free energy for a reaction is less than zero, the reaction is "favored" - it should proceed as written spontaneously. When the Gibbs free energy for a reaction is exactly zero - it is in equilibrium, with the forward and back ward reactions occurring at the same rate.
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
If the Gibbs free energy is close to zero, the reaction is close to equilibrium.