Linked Questions

8 votes
2 answers

What is the difference between ΔG and ΔG "with an o on top"? [duplicate]

What is the difference between $\Delta G$ and $\Delta G^\circ$? I couldn't figure it out. Ex: $\Delta G^\circ = -RT\ln K$ $\Delta G = \Delta G^\circ + RT \ln Q$ What is the difference, is it that $\...
Asker123's user avatar
  • 3,050
0 votes
0 answers

Is there an agreement for a specific temperature referred to in the context of standard Gibbs energy? [duplicate]

I found an exercise in Physical Chemistry by Atkins et al, 8th edition, page 235 that I found confusing. The question is as follows. "7.2(b) Molecular bromine is 24 per cent dissociated at 1600 K ...
Galen N. P.'s user avatar
27 votes
1 answer

Addition of hydrogen bromide to 1,3-butadiene: thermodynamic and kinetic control

The reaction of one equivalent of hydrogen bromide with 1,3-butadiene gives different products at under different conditions:1 The addition of hydrogen chloride also gives rise to similar products.2 ...
orthocresol's user avatar
  • 70.2k
16 votes
2 answers

Is the Gibbs standard free energy always constant?

I am a biochemistry student and we are learning about thermodynamics. Is the Gibbs standard free energy for a reaction always constant? The equation below suggests that it changes with temperature: $$...
ctkw's user avatar
  • 447
14 votes
3 answers

What is the difference between ΔG and ΔrG?

Consider the reaction $$\ce{A -> B}$$ The reaction Gibbs free energy, $\Delta_\mathrm{r} G$ is given by the following equation $$\Delta_\mathrm{r} G = \Delta_\mathrm{r} G^\circ + RT \ln Q$$ Now ...
CLAP or SLAP II's user avatar
12 votes
1 answer

Derivation of van 't Hoff equation for temperature dependence of equilibrium constant

While I was reading about the usefulness of the quantity $\Delta H$, I found that it can be used to calculate the how the equilibrium constant varies with temperature. How can this be done? Does it ...
Kartik Watwani's user avatar
4 votes
3 answers

If change in free energy (G) is positive, how do those reactions still occur?

I was doing a couple of problems for homework: Calculate $K_\mathrm{sp}$ of $\ce{AgI}$ at $55.0\ \mathrm{^\circ C}$ Calculate $K_\mathrm{b}$ of $\ce{NH3}$ at $36.0\ \mathrm{^\circ C}$ I have to use ...
Michael Zheng's user avatar
6 votes
3 answers

Calculating ΔG at the extremes of reaction extent

This question follows on from a great post on comparing $\Delta_\mathrm{r} G^{\circ}$ to $\Delta_\mathrm{r} G$ answered here The G vs ξ graph that is used in the answer is an excellent tool to ...
Withnail's user avatar
  • 1,323
4 votes
1 answer

Do I use the Nernst equation when the concentrations of electrolyte in both half cells are equal?

I'm doing a chemistry report, and for my experiment I investigated the amount of voltage produced by different half cells in a voltaic cell. However, I tested them under nonstandard conditions as ...
Yoyo's user avatar
  • 41
4 votes
2 answers

Change in standard Gibbs energy is always zero?

So I have this statement from our professor : We have $\Delta G^\circ = -RT\ln K$ and under standard conditions the activities of all substances in the reaction is $1$ ($a=1$), therefore $\Delta G^\...
Glacier's user avatar
  • 41
2 votes
2 answers

Gibbs free energy in standard state vs. equilibrium

I have a problem with the definition of the standard Gibbs energy and its connection to the equilibrium constants. I think, that I've basically understood what the different equation mean but there ...
user76122's user avatar
0 votes
1 answer

Temperature in the Gibbs Free Energy equation

My professor gave us 2 different ways to calculate this problem. I did it using the Clausis-Clapeyron equation. However, I don't quite get the second method because I thought that if the change in ...
Cora N's user avatar
  • 111
2 votes
1 answer

Gibbs Free Energy Notation

What's the difference between $G$, $\Delta G$, $\Delta G^\circ$, and $\Delta_\mathrm r G^\circ$? I've seen the first two used interchangably, and seen $G$ specifically referred to as change in Gibbs ...
Vedvart1's user avatar
  • 133
4 votes
2 answers

How come ∆G ≤ 0 is used for spontaneity in electrochemistry, not ∆G ≤ W(other)?

The spontaneity condition for a system at constant temperature and pressure in which the only type of work accomplished is of the $pV$ type can be expressed as: $$\Delta G\le0\tag1$$ In case of ...
Mark Diejs's user avatar
-2 votes
1 answer

What does "heat is evolved at standard-state conditions" mean?

When $\pu{0.539 g}$ of $\ce{Na(s)}$ reacts with excess $\ce{F2(g)}$ to form $\ce{NaF(s)}$, $\pu{13.3 kJ}$ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation ($\...
Mr. Chameleon's user avatar

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