Questions tagged [equilibrium]

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

193 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
6
votes
0answers
48 views

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 ...
6
votes
1answer
199 views

Apparent contradiction in the type of deviation of an ethanol-water mixture

For a mixture of $\ce{EtOH}$ and $\ce{H2O}$: $\Delta H_{\text{mix}} < 0$ (exothermic) and $\Delta V_{\text{mix}} < 0$ (volume contraction). This means that the unlike interactions are stronger ...
5
votes
0answers
148 views

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 $\ce{H+} \text{ and } \ce{OH}$ ...
5
votes
2answers
207 views

Clausius–Clapeyron relation for states of water and vapor

I've seen many questions about this topic on this site, but I still have some issues trying to understand this aspect. Here's what I believe I understood looking at the phase diagram for a pure ...
5
votes
1answer
102 views

On the activity of liquids and solvents in equilibium constants

This is a confusion I've had for quite sometimes, first when learning about equilibria (due to contradicting teachers), then when trying to teach it (due to contradicting sources, in books and on the ...
4
votes
0answers
25 views

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 ...
4
votes
1answer
79 views

Cases when Raoult's law is unsolvable

Setup Consider a closed binary mixture of known total molar composition $n_i$, held at volume $V$ and temperature $T$. The equilibrium phase composition is determined by $\mu_i^{vap} = \mu_i^{liq}$. ...
4
votes
0answers
79 views

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 ...
4
votes
0answers
491 views

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{...
4
votes
0answers
121 views

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 ...
4
votes
0answers
53 views

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 ...
4
votes
1answer
2k views

How to show that when the equilibrium constant is larger than one, some real-life equilibria are still reactant favoured?

My instructor assigned us with this question: When real examples of chemical equilibrium are used, the conclusions about reactant- or product-favoured versus the value of $K$ must be modified (e.g....
3
votes
0answers
56 views

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 &-&...
3
votes
0answers
57 views

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 ...
3
votes
0answers
39 views

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 ...
3
votes
0answers
63 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 ...
3
votes
0answers
58 views

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 ...
3
votes
0answers
362 views

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 ...
3
votes
0answers
262 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: $$\...
3
votes
0answers
226 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 ...
3
votes
0answers
96 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 ...
3
votes
0answers
1k views

Should I round an experimentally determined reaction order to an integer?

For a lab experiment I did, I'm calculating 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}...
3
votes
0answers
656 views

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 $\pu{1 bar}$...
3
votes
0answers
1k views

The distinction between dynamic & static equilibrium

How could we be sure that one certain reaction in equilibrium is dynamic? Since there would be no visible change in vessel, which property of the reaction would provide a proof besides color? Which ...
3
votes
0answers
118 views

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 ...
3
votes
1answer
502 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 ...
3
votes
1answer
3k 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. ...
2
votes
0answers
35 views

Equivalents Triethylamine in Swern-oxidation

Hey folks, so I've been wondering why the use of 5 equivalents of Et3N in this case of a Swern-oxidation is necessary. I have done this reaction succesfully quite a few times now, but all the ...
2
votes
0answers
86 views

Amount of benzoic acid required to alter pH of a NaOH-solution

I am trying to do a practice problem but I can't figure it out: How many grams of benzoic acid needs to be added to 0.10 l of a NaOH-solution with a concentration of 1.0 mM to reduce the pH of said ...
2
votes
0answers
56 views

Given Kd find equilibrium concentrations of the reactants

$$\ce{Biotin + Avidin → Complex}$$ Biotin is a vitamin derivative that binds extremely tightly to avidin (a protein found in egg white) with a $K_\mathrm{d}$ of $\pu{1e-15 M}$. If you make a ...
2
votes
2answers
256 views

Find the pH of an amphiprotic salt dissolved in water at room temperature

Let's say I have a polyprotic acid $\ce{H2A}$ with the following properties: $$ \begin{align} \ce{H2A &<=> HA- + H+} & K_1 &= 1\cdot 10^{-1}\\ \ce{HA- &<=> A^2-+ H+} & ...
2
votes
0answers
61 views

Stoichiometry based on addition of simultaneous equilibria

I read on another equilibrium question that if two equilibria occur at the same time, then it is not accurate with actual stoichiometry to add the two equations and multiply the equilibrium constants $...
2
votes
0answers
48 views

Defining the partial pressure equilibrium concentration

First off, I am not a chemist. I'm an engineer with an interest in thermodynamics for engine simulation for the basis of emissions. So if I have asked something stupid, this will be why. So I am ...
2
votes
0answers
44 views

Existence of single ion activities

I have used Davies equation to find what I believed was single ion activities and multiplied them on concentrations to define the thermodynamic dissociation constants for any kind of buffer to find ...
2
votes
0answers
161 views

How to without calculations understand the liquid-liquid extraction efficiency?

I'm asking myself this question for a very long time and I haven't found a simple an good explanation yet for the fact that it's better (if you want to clean them) to wash your hands two times with ...
2
votes
0answers
260 views

Electrodes involving sparingly soluble salts (Electrodes of the second kind)

Consider the sparingly soluble salt, $\ce{AgI}$ ($K_\text{sp} = 8.52\times10^{-17}$) and a silver electrode (Standard Reduction Potential = $\pu{0.799V}$). $\pu{0.02L}$ of $\pu{0.001M}~\ce{KI}$ ...
2
votes
0answers
44 views

Langmuir parameters for fixed bed continous column

I have prepared a model of fixed bed adsorption column in MATLAB. I have to insert Langmuir parameter value there, so how can I calculate them in case of continuous fixed bed column. I have calculated ...
2
votes
0answers
55 views

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 ...
2
votes
0answers
169 views

When are pure liquids included in the equilibrium constant?

For an esterification reaction of pure liquids only, the equilibrium constant will take into account all species, however for an aqueous based esterification reaction, water is not included in the ...
2
votes
0answers
493 views

How to measure chemical potential

I wonder if there is a way to measure the chemical potential of a substance in a two-component mixture and also to account for its dependence on the number of moles. Explaining it further, suppose ...
2
votes
0answers
39 views

How much additional product forms when small amounts of reactants are added to a reaction at equilibrium?

I am not able to understand how to determine the exact amount of additional product formed when additional reactant is added to an equilibrium reaction. For example consider the reaction: $$\ce{CO2 +...
2
votes
0answers
191 views

Effect of Temperature on Chemical Reaction Equilibrium

here is the question (part I): For part (i), I need some assistance, I cannot figure out how to do the question. I know eventually what to do, it's just working out the equilibrium constants I'm ...
2
votes
0answers
130 views

pH calculation in case of amphiprotic ion

$100\ \pu{ml}$ of $0.1\ \pu{M}\ \ce{H3PO4}$ is titrated with $0.5\ \pu{M}\ \ce{NaOH}$ solution till 2nd equivalence point. Then resultant solution was mixed with $10\ \pu{ml}$ of $0.5\ \pu{M}\ \ce{HCl}...
2
votes
0answers
1k views

Why do fluoride ions “win” over thiocyanate ions in a solution with iron ions?

When you mix aqueous iron(III) nitrate and potassium thiocyanate together you get a red solution. Then if you add sodium fluoride, the red colour disappears. This is basically because the $\ce{Fe(...
2
votes
0answers
890 views

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. ...
2
votes
0answers
79 views

le chateliers principle

One of le chateliers principle is effect of concentration change : When the concentration of any of the reactants or products in a reaction at equilibrium is changed , the composition of ...
2
votes
0answers
2k views

Why does changing the dilution of an aqueous equilibrium shift the equilibrium?

Say we have the equilibrium $$\ce{A_{(aq)} + 2B_{(aq)} <=> C_{(aq)} + D_{(aq)}}$$ meaning the formula for the equilibrium constant is $$\ce{K_{c} = \frac{[C][D]}{[A][B]^2}}$$ My understanding is ...
2
votes
0answers
448 views

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-}]>...
2
votes
0answers
75 views

Equilibrium Problem Involving Solids: Faulty?

I am convinced that this is a faulty problem: $\ce{2 Cu + S -> Cu2S}$ For the reaction above, $\Delta H$, $\Delta S$, and $\Delta G$ are all negative. Which of the substances would ...
2
votes
0answers
304 views

Apparent solubility of Ag2C2O4 in a buffer solution

We take the following quantities and mix them together: $\pu{20 mL}$ solution of $\ce{AgNO3}$ $\pu{0.001 mol//dm3}$ $\pu{20 mL}$ solution of $\ce{H2C2O4}$ $\pu{0.200 mol//dm3}$ $\pu{40 mL}...