# Questions tagged [equilibrium]

The state in which both reactants and products are present at concentrations which have no further tendency to change with time.

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### Gibbs Free Energy, Temperature and Equilibrium

I was recently taught one of the Gibbs Free Energy formulas, where the change in Gibbs Free Energy is related to the change in enthalpy and entropy ∆G = ∆H - T∆S, and that the system is at equilibrium ...
1 vote
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### Why doesnt Grignard reagent precipitate in ether?

I read that Grignard reagents are stabilised in ether by the coordinate bond formation, but according to the Schlenk equilibrium, RMgX is in equilibrium with MgX2 and R2Mg. Here MgX2 is ionic and thus ...
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### Prove that concentrations of all species increase ultimately in a chemical equilibrium when pressure is increased

The statement: For a chemical equilibrium in a sealed container, the concentration of "all" species always increases when the pressure of the mixture is increased by decreasing the volume of ...
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### Mass conservation in chemical equilibria

Please help me understand this, it's really confusing me! So suppose we have an equilibrium $\ce{A <=> B}$, and that we have initial masses $m_{\text{A}}$ and $m_{\text{B}}$ of the substances. ...
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### How do you use entropy and enthalpy to explain how chemical reactions come to equilibrium?

Let's say I have a reversible chemical reaction between A and B that will come to equilibrium in a closed system. How do I use the concepts of enthalpy, entropy and naturally then, Gibbs free energy, ...
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### Algebraic method for modelling sodium acetate in solution

For a solution of sodium acetate ($NaA$), I want to find the concentrations of $H^+$, $OH^-$, $HA$ and $A^-$ via the algebraic method, being the total concentration of $NaA$ $C_A=0.25~\text{M}$, the ...
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### How can adding a strong base to a weak base be the same as a strong base in solution problem?

In professor's lecture on acid-base titration, professor says (at this point of the video, link should start about the time she says it) "adding a strong base to a weak base should be treated as ...
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### Iodine/iodide electrochemistry help

I have an electrochemistry experiment with iodine in solution. I am initially wanting to quantify the iodide in solution and extrapolate the concentration of I2(aq) and I3-(aq) in solution from this ...
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### Derivation of Gibbs phase rule

I learnt about the Gibbs phase rule a while back but did not really think too much about how it was derived. I am now currently looking back at the derivation provided in the textbook and I realised ...
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### Bicarbonate concentration in the RO permeate

I am facing a challenge since long ago, but have not been able to find a suitable solution for it. Please share your thoughts if you have the knowledge or experience in this area. I am running an RO ...
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### Does copper(II) hydroxide dissolve in ammonia solution?

According to University of Oregon — Chemistry Interactive Demonstrations and Educational Resources — Copper-Ammonia Complex, the equilibrium constant for the formation of copper(II) hydroxide is ...
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### Drug dosage determination using dynamical systems

I am a Mathematical Biology student, and recently I have read about various approaches, such as Ordinary Differential Equations (ODEs), used to determine the exact drug dosage and treatment sessions ...
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### What is the reason behind atoms/molecules in reversible reactions reverting back to its reactant state even if they have found stability? [closed]

If atoms and molecules aim for stability and equilibrium, then why do they feel the need to revert back into their original state once they have already found stability? Example: $\ce{I2 + H2 \to 2HI}$...
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### Calculation of Reaction Extent as a Function of Pressure and Temperature: Issue with Activity-Based Approach

I'm working on modeling reactions involving combinations of hydrogen (H), nitrogen (N), and strontium (Sr) elements. I've obtained the temperature-dependent Gibbs free energy of formation, enthalpy, ...
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### Understanding the relationship between Delta G and Kp, Kx and Kc

**Upon reading the chapter about equilibrium from my physical chemistry book, I was convinced that ΔG=−RTln(Kp)(1) and that Kp=Kx(P∑v)(2) where Kp is the equilibrium constant with respect to pressure ...
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### How does cell potential change with temperature for positive enthalpy and negative entropy?

A recent United States National Chemistry Olympiad question asked: A certain voltaic cell has a standard cell potential that increases with increasing temperature. Which best explains this ...
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Lead nitrate reacts with sodium carbonate to form lead carbonate, if sodium carbonate is in excess will the white precipitate of lead carbonate dissolves ? Like in lead nitrate reaction with excess of ...
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### Calculation of Kc

Gaseous hydrogen and gaseous iodine react together to form hydrogen iodide. H2 + I2 ⇌ 2HI The graph shows how the amount of hydrogen iodide varies with time in a 1.00 dm3 container. The initial ...
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1 vote
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### How can equilibrium constant be derived by irreversible reaction?

I am solving the example from the book [Essentials of Chemical Reaction Engineering, Chapter 3, P3-12B] and finding out a contradictive point. "The rate law for the A->B reaction was obtained ...
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### Reversible and irreversible reactions [closed]

I searched that an reversible reaction can be made irreversible by removing its product. I am wondering if catalysts can help produce the same effect. And I'd also like to know, if actually an ...
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### How is it even possible that vapour pressure of liquid and vapour of solid are equal at freezing point? [duplicate]

My text book states The freezing point is defined as "the temperature at which the vapor pressure of the substance in its liquid phase is equal to its vapor pressure in the solid phase" Also ...
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### Hydrolysis of $A_3B$ type weak acid-weak base salt

I know the formulae for weak acid-weak base salt of AB type. A peculiar question made me ask this. Do the formula for derived for AB type also hold for A3B type sal. For example: This is the question, ...
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### Find the pH of a solution obtained by mixing 100 ml 0.1m Na3PO4 and 100 ml 0.1 M NaH2PO4. Given that H3PO4: [Κα₁ = 10^-4, Κα₂ = 10^-7, Каз = 10^-11] [closed]

So, my query is that since NaH2PO4 is a weak acid, and Na3PO4 is a basic salt, wouldn't they react? Another theory was that since NaH2PO4 is a weak acid and Na3PO4 is a salt of strong acid and NaH2PO4,...
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### Can phosphorous penta hydroxide [P(OH)5] exist? [closed]

I was looking at the oxyacids of Phosphorous and it is given that (in Wikipedia article of "Phosphorous acid"), some of these acids (Eg: $H_3PO_2$ and $H_3PO_3$) exist in a dynamic ...
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### Isoelectric Point

How do we derive the formula of isoelectric point? pI=(pKa1 + pKa2)/2 I read that isoelectric point is defined as the pH at which degree of protonation in amino group is same as degree of ...
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### Bancroft's point

In the last problem (Problem 10.43) within the problem section of Chapter 10 in "Introduction to Chemical Engineering Thermodynamics" (J.M. Smith, H.C. Van Ness, M.M. Abbott, McGraw-Hill, ...
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### Why is the ionic product of water also the equilibrium constant of dissociation of water?

This answer presents a derivation of the value of ionic product of water at $25^{\circ}\text{C}$. The relation $K_\text{eq} = \operatorname{e}^{-\frac{\Delta_\text{r}G^{\circ}}{RT}}$ is used for the ...
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### Inconsistency in between Nernst Equation and Gibbs Free Energy Equation [closed]

Part 1 - Derivation of the Gibbs Free Energy Equation: [copied from this] Using the fundamental equations for the state function (and its natural variables): \begin{align} \mathrm{d}G &= -S\...
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### How salt helps to melt ice even when there is no dynamic equilibrium between water and ice?

I am a high school student and I am confused about freezing point depression. We say that when in winter's it gets even colder than normal freezing point Temperature then we use solute to melt ice ...
I read a question on a textbook that asked: For the reaction $$\ce{CaCO3(s) \rightleftharpoons CaO(s) + CO2(g)} \tag{1}$$ determine whether or not a mixture of $\ce{CaCO3(s)}$ and $\ce{CO2(g)}$ at a ...