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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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Metal hydrolysis and equilbrium constants from stability constants

Problem: I want to create minimum solubility plots for a series of metal hydrolysis species against pH (below). But I cannot reconcile literature stability constants and equilibrium constants. Context:...
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Which xylenes, if any, are immiscible with DMSO?

"Xylene" is reported to be immiscible with dimethyl sulfoxide (DMSO), according to a few solvent miscibility tables found online (chart 1, chart 2, chart 3). I have tried to locate some ...
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Using Le Chatelier's Principle to Change Mechanical Energy to Chemical Energy

I was interested in an application of Le Chatelier's principle, where an increase in pressure could result in a decrease in the moles of gas. In particular, a situation where when the pressure ...
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How can copper(II) sulfate crystallize outside a glass vial?

I'm making copper sulfate crystals in glasses. Within a few weeks, the copper sulfate seems to crystallize both inside and outside the glass: (A few weeks after making a new solution) (Yet another ...
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Why does pKw first decrease but eventually increase when temperature rises?

I understand the initial decrease in pKw. $\ce{Heat + H2O (l) <=> H+ (aq) + OH- (aq)}$ Temperature increases, reaction shifts to the right, so $\ce{H+} \text{ and } \ce{OH}$ ...
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Equations Used in Isothermal Titration Calorimetry

I have been attempting to understand and derive the formulas used for ITC which can be found here starting on page 310. I am particularly interested in the single set of identical sites. To first ...
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Should I round an experimentally determined reaction order to an integer?

For a lab experiment I did, I calculated the reaction order for one of the reactants using data from two trials, both rates, and the concentration of that reactant during each. $$ \frac{\text{Rate}_1}{...
Caesium-133's user avatar
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What does the equilibrium constant mean for reactions with very small concentrations?

When you calculate the equilibrium constant for a reaction with a higher concentration of reactants, the answer is fairly intuitive. For example, for the reaction: $$\ce{A + B <=> C}$$ when we ...
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Regarding Ellingham diagrams

In my textbook, the following information is given about Ellingham diagram: The interpretation of $\ce{\Delta_rG^\circ}$ is based on ${K}$ ($\ce{\Delta G^\circ = -RTlnK}$). Thus it is presumed that ...
Pal's user avatar
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Decomposition of Hydrogen Peroxide Catalysed by Potassium Iodide in Basic Solution

As part of my high school project, I had to measure the initial rate of decomposition of hydrogen peroxide catalysed by potassium iodide at different pHs. At higher pHs (alkaline conditions), I found ...
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Why does equilibrium for the addition of the Claisen enolate to an ester not favor the product?

I am currently reading chapter 26 of Clayden's Organic Chemistry, and a diagram for the elementary steps of the Claisen condensation with ethyl acetate in ethoxide is provided. It is obvious why the ...
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Is entropy maximum in equilibrium?

Usually, in the context of non-equilibrium thermodynamics, it is said that entropy achieves a maximum in equilibrium, so the Taylor series expansion of entropy around the equilibrium state as a ...
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How are σ+ values in Hammett Plots calculated?

First of all, I know a similar question has already been asked & answered about σ values in general, however, I am not 100 % sure this answer is correct for the following situation. So for the σ ...
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Computing the turbulent flame length

There is a problem I found online for practice that I cannot solve: Problem Methane, $\ce{CH4}$, emerges from a $1\ \mathrm{cm}$ diameter nozzle at a rate of $120\ \mathrm{cm^3/s}$ and a mole ...
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Validity of the equation K_eq = ratio of rate constants of forward and reverse reactions

If we have a multi-step reaction (which involves more than one step to reach the products; a complex reaction, one may say), then is the following equation valid? $$K_\mathrm{eq} = \frac{K_\mathrm{...
Senthil Arihant's user avatar
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Model CO2-C6F14 Vapor Liquid Equilibrium with an Equation of State

I'm trying to model the VLE for a binary mixture of CO2 and C6F14 using a cubic equation of state (e.g. Peng-Robinson) for both the liquid and the vapor phase (phi-phi approach). From available data ...
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Iminium formation rate between formaldehyde and secondary amine

Given the significantly more favored hydrate of formaldehyde in the presence of water under neutral conditions, can we say that this is the slow step in iminium formation? Would removing water/working ...
moreQthanA's user avatar
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1 answer
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How can a Michaelis–Menten formalism be used when enzyme concentration isn't constant?

I understand that $V_\mathrm{max} = k_3[\ce{E}]_0$ in ordinary Michaelis–Menten (MM) kinetics. According to the lecture notes provided by my university (I don't believe they are available online), ...
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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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Does real-world gas phase chemistry use "concentration reaction quotients" (K_c)?

As a theoretical chemist, my entire exposure to reaction quotients and equilibrium constants ($Q$ and $K$) is through thermodynamics ($\Delta G^\ominus = - RT \ln K_{eq}$ and so on). So as I started ...
Shern Ren Tee's user avatar
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Equilibrium constant of the formation of ferric thiocyanate

I was reading the paper Relaxation Kinetics of Ferric Thiocyanate (Goodall et. al, 1972) and I came across a passage which read $\space$ Reaction (1) is the simplest representation of the equilibrium ...
Cold_Spaghetti's user avatar
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308 views

Derivation of the Van 't Hoff equation

I was reading the paper Relaxation Kinetics of Ferric Thiocyanate (Goodall et. al, 1972) and I came across the passage Reaction (1) is the simplest representation of the equilibrium between ferric ...
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106 views

Equilibrium concentrations of CO and Cl2 by dissociation of phosgene

I am working through a problem set from MIT's open courseware course Principles of Chemical Science. The question is: Phosgene $\ce{(COCl2)}$ is a chemical warfare agent that decomposes by the ...
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Is dehydration of cobalt(II) chloride hexahydrate dynamic equilibrium?

I know that the dehydration of cobalt(II) chloride hexahydrate is a reversible reaction, is it a dynamic equilibrium? $$ \begin{align} \ce{CoCl2·6H2O &<=> CoCl2·2H2O + 4 H2O}\tag{R1}\\ \ce{...
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170 views

Why aren't electrons included in the equilibrium constant expression?

This might be elementary, but why aren't electrons included in the equilibrium constant for a half-reaction? For example, for $$\ce{O2 (g) + 4H+ (aq) + 4e- -> 2H2O(l)}$$ we have $$Q = \frac{(a_\ce{...
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How can the activity of ions be more than 1 if the activity of water is 1?

Now, I am quoting Chemlibretexts when they give the activity coefficient of $\ce{LiCl}$ to be $\pu{1.026}$ at the molality of $\pu{2.5 mol kg-1}$ For simplicity, assuming this is aqueous, I'll just ...
ReveaZapcre's user avatar
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195 views

What does isohydric solution mean?

While studying ionic equilibrium, I came across the term "Isohydric Solutions" which is defined as: Solutions of electrolyte are said to be isohydric if the concentration of the common ion ...
John's user avatar
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Why does high blood gas partition coefficient of a inhalational anaesthetic drug mean slower induction of anesthesia?

High blood gas partition coefficient of a drug corresponds to higher solubility of the drug in blood leading to high concentration of the drug in blood with respect to gas (air in alveoli). If the ...
Kavya Chandrasekaran's user avatar
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317 views

Is the active mass of every solid and liquid taken to be unity?

I learnt from my textbook and the question/answer - Why is active mass of a pure solid or liquid always taken as unity? that active mass of a solid or liquid is taken to be unity as: $$[A]=\frac n V=\...
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Common ion effect

Let $\ce{HA}$ ($x$ molar) be a strong electrolyte and $\ce{HB}$ ($c$ molar) — weak electrolyte. As $\ce{HA}$ is strong electrolyte, it dissociates completely: $$ \begin{array}{lcc} \ce{&HA &-&...
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Reverse rate coefficient for thermolecular and thermal dissociation reactions

I am an astrophysicist working in exoplanetary atmosphere chemistry right now, in particular modelling the chemical kinetics taking place within the atmosphere. Based on this IOP article, we have that ...
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Elegant solutions to non-conjugate buffer systems: ammonium carbonate, pyridinium dihydrogen phosphate, lysine and glutamic acid etc

Okay, this has really been frustrating me as a tutor because there is such few materials online on what to do in this case (besides use a brute-force method with systems of equations). Almost every ...
Yanping Nora Soong's user avatar
3 votes
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97 views

Which of the following is more stable?

In this image, does the arrows indicate correct rate of reactions? The upper arrow is longer and lower is shorter. According to me Chair is more stable than Twist Boat. Does axial and equatorial ...
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Formating chemical equations for proteins binding in multiple configurations

I am working on problems involving protein-protein binding, particularly ones in which two proteins may bind in two or more configurations, and where some of the resultant structures may also bind ...
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What solution is not in equilibrium?

An example of a solution not in equilibrium (A) Chemical ph indicator (B) Acid/base buffer (C) Anhydrous solution (D) hypotonic solution (E) Supersaturated solution I eliminated A and ...
Elena Kolumba's user avatar
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0 answers
541 views

Enthalpy change of chromate-dichromate reaction

I am a uni study doing chemistry. I have taken a little bit in highschool before, but not in a while. In a (nonassessed) practical, we have to predict how heating a chromate/dichromate solution: $$\...
leob's user avatar
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Why are the stoichiometric coefficients used as exponents in the chemical equilibrium constant?

From what I can ascertain, the formulation of the chemical equilibrium constant is somewhat arbitrary. I don't understand the motivation for putting the stoichiometric coefficients in the exponents. ...
user1934868's user avatar
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Electrolysis of dilute and concentrated sodium chloride and the Nernst equation

Interested to know if there is a critical concentration at which $\ce{Cl-}$ will oxidise over $\ce{H2O}$ and if this can be determined using the Nernst equation. That is, obviously if $[\ce{Cl-}]>...
Pravin Singh's user avatar
3 votes
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328 views

The behaviour of Ag3PO4 in solution

To a $\pu{1L}$ flask, we add $\pu{4.1900 g}$ ($\pu{0.01001 mol}$) of $\ce{Ag3PO4}$, then fill it up with water. Knowing the following constants, we are asked to find the concentration of all species ...
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0 answers
141 views

What happens at equilibrium for two solutions that produce gasses?

Suppose one has two chemical reaction equations: $\ce{A_{(aq)} + B_{(aq)} <=>[H2O] C_{(g)} + D_{(g)}}$ and $\ce{A_{(s)} + B_{(s)} <=> C_{(g)} + D_{(g)}}$ Suppose one puts 0.1 mol of A ...
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Dissociation percentages of N2O4 at different pressures using Gibbs' free energy

\begin{align} \ce{N2O4(g)&<=>2NO2(g)} & \Delta_\mathrm{r}G^\circ &= \pu{4.7 kJ mol^-1} \end{align} Knowing that the standard values for pressure and temperature are $\pu{1 bar}$...
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How much of the anion species is left over after the first precipitation?

Some barium chloride is added to a solution that contains both $\ce{K2SO4}$ ($\pu{0.050 M}$) and $\ce{Na3PO4}$ ($\pu{0.020 M}$). (a) Which begins to precipitate first: the barium sulfate or the ...
readyready15728's user avatar
3 votes
1 answer
165 views

Why does the equation for chemical potential apply to liquids and aqueous solutes?

The equation for chemical potential of a gas can be derived as such: At constant temperature, $$\mathrm dG = V\,\mathrm dP \label{eqn:1}\tag{1}$$ Substituting with the ideal gas law $PV = nRT$, $$\...
Heat's user avatar
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3 votes
1 answer
908 views

Equilibrium Constants For Phenol Tautomers

I encountered the following equilibrium constant values for the keto-enol interconversions of phenol in Organic Chemistry (Solomons, Fryhle, Snyder, 3rd Edition): I wonder what could explain the ...
Kartik's user avatar
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3 votes
1 answer
921 views

Do ligands in ionisation isomerism interchange?

The text says: This form of isomerism arises when the counter ion in a complex salt is itself a potential ligand and can displace ligand which can then become the counter ion. For other ...
Ayush Sharma's user avatar
3 votes
1 answer
5k views

Le Châtelier’s Principle and Addition of Water

With regards to gas volume, Le Châtelier’s principle predicts that an increase in the volume of the container causes the system to favor the side of the reaction that produces more moles of gas. ...
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2 votes
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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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0 answers
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Phase diagram of ammonium hydrosulfide, a volatile salt

Salts (ionic compounds) usually have low volatility due to the strong ionic bond. However, there are exceptions. Smelling salts decompose and release ammonia gas. What is "volatile"? If a ...
Kevin Kostlan's user avatar
2 votes
0 answers
39 views

Is the amine nitrogen of methylglycinediacetic acid (MGDA) protonated?

MGDA is a tertiary amine with 3 acetic acid groups. I would like to know whether the amine Nitrogen of MGDA is protonated or not for a given pH value. I could not find any literature data which ...
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Interpreting Ternary Phase Diagram Stoichiometry

I am trying to locate the lowest-melting mixture in a system of three nitrate salts: sodium, potassium, and calcium nitrate. I have the relevant ternary phase diagram, but I am unsure exactly about ...
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