Delta G and G naught
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Delta G and G naught
What is the difference between Delta G and Delta G naught? And how do you know which equation to use in problems?
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Re: Delta G and G naught
DeltaG naught is deltaG at standard conditions. You will not always be doing reactions at standard conditions so we have an equation to convert between the two. Problems that ask for dG naught will typically ask for dG of a reaction done under standard conditions
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Re: Delta G and G naught
Delta G naught is at standard conditions. You will know to use this in your equation if they give the standard condition values or say that the system is under standard conditions.
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Re: Delta G and G naught
As others have stated deltaGo is the deltaGunder standard conditions. However, I think what's most important to remember about the relationship between deltaGo and deltaG is that they can be used to find each other given Q as deltaG = deltaGo + RTln(Q).
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Re: Delta G and G naught
As the others said, ΔG naught is the change in gibbs free energy at standard conditions as opposed to ΔG. What helped me distinguish when to use the equation for these terms was that you usually have to find ΔG naught when given K and ΔG when just giving either Q, or the concentrations/pressures of the reactions and products.
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Re: Delta G and G naught
Also, it's good to note that STP (standard temperature and pressure) is 273 K (or 0°C) for temperature and 1 atm for pressure. :)
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Re: Delta G and G naught
Delta G is at standard conditions. standard conditions are 1 atm and 298 K (room temp, 25 degree Celsius)
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Re: Delta G and G naught
Delta G naught is the standard reaction Gibbs free energy. If the reaction is not occurring at standard conditions, then regular gibbs free energy is used, which takes into account variations in the temperature, pressure, and anything else.
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Re: Delta G and G naught
Also remember in addition to deltaG = deltaGo + RTln(Q), deltaG equals 0 at equilibrium, which gives you deltaGo = -RTln(K) at equilbrium!
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Re: Delta G and G naught
Delta G naught is the change in Gibbs free energy at standard conditions, whereas Delta G is the change at a specific condition. The key to determining which to use is to see if standard condition values are given or if the system is at equilibrium, then that means Delta G is zero.
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Re: Delta G and G naught
Delta G is the change in Gibbs free energy at any conditions, while delta G naught is the change in Gibbs free energy change at standard conditions (e.g. 298K and 1 atm).
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Re: Delta G and G naught
Delta G not is at standard conditions, and delta G is at any temperature. You can use delta g not to find the delta g at other temperatures
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Re: Delta G and G naught
The main difference between delta G and delta G naught is that delta G naught is delta G at standard conditions (1atm and 25 degrees Celsius / 298.15 K).
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Re: Delta G and G naught
Delat G naught is change in Gibbs free energy under standard conditions (1 atm, 298 K), while delta G is not in these conditions. Delta G naught can be used to find delta G, equations are included on the eq/constant sheet to calculate the two.
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Re: Delta G and G naught
delta G refers to Gibbs free energy. While delta G naught refers to standard Gibbs free energy, which is free energy at standard conditions (298 K and 1 atm).
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Re: Delta G and G naught
Using the information that many people have stated above, I think its also important to note that if delta G is negative it is spontaneous, and positive is not spontaneous. However, knowing the sign of delta G naught does not prove spontaneity. Because, according to the equation for delta G, there are other factors that might affect the reaction.
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Re: Delta G and G naught
Delta G naught is the change in Gibbs free energy at standard conditions (1 atm and 25 degrees Celsius/298.15 K) , whereas Delta G is the change at a specific condition.
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Re: Delta G and G naught
Delta G naught is at standard conditions, whereas Delta G isn't at standard conditions necessarily.
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Re: Delta G and G naught
Delta G simply just refers to the free energy of the system. The delta G naught often refers to a more specific standard conditions of free energy.
Re: Delta G and G naught
Anything "naught" is typically at standard conditions. Most things don't occur under standard conditions, so you would have to use deltaG instead. Think of deltaGnaught as like, the unobtainable ideal.
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Re: Delta G and G naught
Delta G is Gibbs free energy while Delta G naught is the standard Gibbs free energy. Its delta G that tells you if a system is at equilibrium (if it equals 0), not delta G naught.
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Re: Delta G and G naught
Delta G naught is simply Delta G under standard conditions (273 K / 0˚C, 1 atm).
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Re: Delta G and G naught
Delta G nought is fixed for a given reaction and temperature and so it does not change as the reaction proceeds. Delta G, on the other hand, depends on the composition of the reaction mixture and so it varies as the reaction proceeds.
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Re: Delta G and G naught
Do Delta G and Delta naught have the same units? Or does it depend on the situation?
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Re: Delta G and G naught
@Ellison I believe delta G and delta G naught can have the same units! Usually it's kJ/mol
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Re: Delta G and G naught
Naught is telling you that the system is at standard conditions of temperature and pressure.
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Re: Delta G and G naught
is at standard conditions (298K and 1atm). You can use the equation = +RTlnQ to determine its relationship.
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Re: Delta G and G naught
Delta G nott is under standard conditions while delta G (no nott) is under not standard conditions.
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Re: Delta G and G naught
Delta G naught is the value when applied under standard conditions. Delta G refers to the free energy of the system and is dependent on variables such as temperature and where the reaction proceeds.
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Re: Delta G and G naught
The little degree sign that reads "naught" represents standard conditions, so Delta G Naught is Delta G at standard conditions. (Same thing goes for Delta H Naught and Delta S Naught)
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Re: Delta G and G naught
Sedge Greenlee wrote:As others have stated deltaGo is the deltaGunder standard conditions. However, I think what's most important to remember about the relationship between deltaGo and deltaG is that they can be used to find each other given Q as deltaG = deltaGo + RTln(Q).
So if deltaG = 0, does that mean that deltaGo= RTln(Q) ? Or does that relationship not exist?
Re: Delta G and G naught
Delta G by itself is the free energy of a particular system; Delta G naught is the standard conditions of free energy for a system.
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Re: Delta G and G naught
Delta G naught is when the reaction is in standard conditions and the reaction is at equilibrium, whereas Delta G is at any moment during a reaction!
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Re: Delta G and G naught
Delta G naught is under standard conditions, while G can change as the reaction progresses.
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Re: Delta G and G naught
∆Gº is ∆G at standard conditions, while ∆G can be under any conditions and they vary with the conditions.
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Re: Delta G and G naught
Vanessa Perez wrote:Sedge Greenlee wrote:As others have stated deltaGo is the deltaGunder standard conditions. However, I think what's most important to remember about the relationship between deltaGo and deltaG is that they can be used to find each other given Q as deltaG = deltaGo + RTln(Q).
So if deltaG = 0, does that mean that deltaGo= RTln(Q) ? Or does that relationship not exist?
Well, since when deltaG = 0, the system is at equilibrium, so Q would = K. This means that the relationship isn't deltaGo = -RTlnQ but instead deltaGo = -RTlnK (an equation on our constants sheet)!
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Re: Delta G and G naught
Whenever you see a naught, that means that the problem is occurring at standard conditions.
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Re: Delta G and G naught
refers to the change in Gibbs Free Energy, whereas refers to the change in Gibbs Free Energy under standard conditions (P=1 atm, T=273K).
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Re: Delta G and G naught
One difference between the two is that deltaG naught isn't always equal to 0 at equilibrium (negative when K>1, positive when K<1, and 0 when K=1) while delta G is equal to 0 at equilibrium (no work done).
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Re: Delta G and G naught
Like many have stated, delta G naught is at standard conditions, while delta G is not
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