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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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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Numerically solving chemical equilibrium equations
Here are chemical equilibrium equations:
$\begin{cases}
\mathbf{N}^\text{T}\mathbf{X}+\mathbf{C}=\mathbf{Y}\\
\mathbf{N}\ln\mathbf{Y}=\ln\mathbf{K}
\end{cases}$
Here $\mathbf{C}=\begin{pmatrix}c_1\\...
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How to calculate the pH of a mixture of an acid with a buffered solution?
Being a physicist by training, having worked in software development for the last 10 years. Having heard my last chemistry lecture 15 years a go I am a bit lost in regards to how one can calculate the ...
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Algebraic method for modelling sodium acetate in solution
For a solution of sodium acetate ($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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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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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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pKa of acetic acid in pure NH3?
Acetic acid completely dissociates in liquid ammonia and I would like to know the $\mathrm{p}K_\mathrm{a}$ value for the acid in that solvent. Can anybody point me to a reference?
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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(...
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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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If a pocket of nitrogen gas is pumped in at the bottom intake of a padded tank will the pocket of gas bubble up?
I have a nitrogen gas padded tank (tank 1) which is filled from the bottom of the tank. Tank has a set point of 30 psi which adjusted as tank level changes. Also at the inlet is an additional pipe ...
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Effect of Pressure on Equilibrium
This might be a little bit of a basic question, but I've been trying to get my head around pressure and Le Chatelier's principle and I can't quite understand it.
Currently, my understanding of Le ...
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Why does balancing the reduction of dichromate(VI) to chromium(III) require four water molecules among the products?
Problem
Balance the following chemical equation using oxidation numbers:
$$\ce{Cr2O7^2–(aq) + HNO2(aq) –> Cr^3+(aq) + NO3–(aq)}$$
Solution (in Swedish)
$$\ce{\overset{+VI}{Cr}_2O7^2–(aq) + H\...
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How is dG=0 employed to describe equilibrium in constant volume systems?
GIBBS ENERGY
Here's the derivation of how dG=0 describes equilibrium state:
$$\Delta S_{\text{system}} + \Delta S_{\text{surrounding}} > 0$$
$\implies\Delta S_{\text{system}} + \frac{-Q}{T_{\text{...
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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 ...
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Meaning of letter K in chemistry conventions [duplicate]
The letter "K" is usually used as chemistry (or statistics/ physics) conventions, take the equilibrium constant (Kc) and rate constant (k) as two prime examples.
Are there any reasons why &...
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Is the reaction product favoured in this equilibrium: H2(g)+I2(s)><2HI(g) when K=45? [closed]
Is the reaction product favoured in this equilibrium: H2(g)+I2(s)><2HI(g) when K=45?
or is the reaction reactant favoured? because I remember that if K>1 then the product is favoured. I am ...
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Is there a difference between equilibrium and steady state?
The term equilibrium is used in the context of reversible reactions that reach a point where concentrations no longer change. The term steady-state is used in enzyme kinetics when the concentration of ...
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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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Will the total equilibrium pressure increase in gas phase reaction PCl5(g) ⇌ PCl3(g) + Cl2(g) after chlorine is removed?
Will the total pressure be greater than the initial equilibrium pressure if all $\ce{Cl2}$ is removed and the following reaction is allowed to re-equilibrate?
$$\ce{PCl5(g) <=> PCl3(g) + Cl2(g)}$...
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Increase in equilibrium concentration of the reactant via decrease in container volume
Consider the hypothetical reaction $\ce{3A(g) -> B(g) + C(g)}$; how to increase the equilibrium concentration of $\ce{A}$, given that the reaction is endothermic?
increasing the volume of ...
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Single electrode potential measurement
My textbook says that in a galvanic cell, it's not possible to measure single electrode potential independently. Instead, a Standard Hydrogen Electrode is used as the system is under equilibrium. Can ...
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Resolve inconsistency regarding percentage of ionized water molecules in the auto-ionization of water
I am relearning some chemistry in order to understand pH for a particular application. My last encounter with the subject was in high school several decades ago. I have the following question:
I read (...
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Effect of Pressure on the Position of Equilibrium
The following general reaction proceeds with decrease in amount of substance, so increasing pressure should shift the position of equilibrium to the right.
$$\ce{2 A(g) <=> B(g)}$$
But let's say ...
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Considering Le Chatelier's principle, what happens when you add more solute to a saturated solution already in equilibrium?
If I'm not wrong saturated solutions are in dynamic equilibrium. Will the addition of solute disturb the equilibrium? What exactly occurs and how to apply Le Chatelier's principle?
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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:
$$\ce{CO2 +...
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How would I find the molarity/concentration of a gas using pV = nRT?
The problem I'm working on is:
At $\pu{1100 K}$ and a total pressure of $\pu{1 atm}$, $\ce{SO3}$ is $75.0\%$ dissociated.
$$\ce{2SO3(g) <=> 2SO2(g) + O2(g)}$$
Assume $\pu{1.00 mol}$ of $\ce{SO3}...
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Phase diagram of ammonium hydrosulfide, a volatile salt
Salts (ionic compounds) usually have low volatility due to the strong ionic bond.
However, there are exceptions. Smelling salts decompose and release ammonia gas.
What is "volatile"?
If a ...
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Should I round an experimentally determined reaction order to an integer?
For a lab experiment I did, I calculated the reaction order for one of the reactants using data from two trials, both rates, and the concentration of that reactant during each.
$$
\frac{\text{Rate}_1}{...
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What is 'spray foam' or 'expanding foam'?
At the wikipedia are:
Spray foam (expanding foam in the UK) is a chemical product created by two materials, isocyanate and polyol resin, which react when mixed with each other and expand up to 30-60 ...
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Does solubility product dictate predominant precipitate from the solution with several ionic compounds?
While removing temporary hardness through boiling, magnesium bicarbonate will give $\ce{Mg(OH)2}.$ $\ce{Mg(OH)2}$ predominates over $\ce{MgCO3}$ as the solubility product $K_\mathrm{sp}$ of $\ce{Mg(OH)...
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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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Is vapour pressure of a liquid solution constant at a given temperature, no matter the size of closed container and amount of liquid taken?
Does vapour pressure of a liquid solution depend on the size of the closed container, the amount of solution taken, given that, the temperature is kept constant? Or will it change if some extra gas is ...
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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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Equilirium mixture of nitrogen dioxide and its dimer
When an equilibrium mixture of gaseous, colorless $\ce{N2O4}$ and brown $\ce{NO2}$ is warmed at constant volume, which of the following is correct?
The density remains constant.
The degree ...
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Boiling point, pressure, and Gibbs free energy
The water boiling process can be represented by the equation:
$$ \ce{H2O(l) → H2O(g)} \tag{1} $$
Since free energy depends on pressure
$$ \left(\frac{\partial G}{\partial P}\right)_T = V \tag{2} $$
...
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Solubility of lead carbonate
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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Why does water dissociate to H3O+ and OH- rather than H+ and OH-?
Why does water dissociate to
$\ce{H3O+ + OH-}$
instead of $\ce{H+ + OH-}$?
This question came to surface when I was learning about acids and bases, and learned this definition:
$\mathrm{pH=}-\log_{10}[...
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Finding the molar ratio at equilibrium
Consider the reaction $\ce{SO_2_{(g)} + \frac{1}{2} O_2_{(g)}\longrightarrow SO_3_{(g)}}$. What effect is there on the molar ratio $\frac{n_{SO_3}}{n_{SO_2}}$ at equilibrium if the pressure is ...
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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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Acid dissociation constant from conductometric data
$\ce{0.007 M}$ aq. solution of anilinium hydrochloride had molar conductivity equal to $\pu{119.4 S cm2 mol-1}$, which became $\pu{103 S cm2 mol-1}$ when a few drops of aniline were added to the ...
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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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