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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Water Gas Shift Reaction

Considering the water-gas shift reaction $$\ce{CO(g) + H2O(g) <=> CO2(g) + H2(g)},$$ I would like to understand how evolves $K^\circ$ the equilibrium constant of this reaction when I add water ...
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Is my calculated equilibrium constant reasonable for my reaction? [closed]

My reaction is Fe3+ + SCN- <=> FeSCN2+ My data at 20 degrees Celsius My calculated equilibrium constants using the following formula I tried finding literature online but I couldn't find any ...
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Gibbs free energy change in reversible and irreversible reaction

Why is ∆G in reversible reactions dependent on the concentrations of the reactant and the product while in the case of irreversible reactions independent of the concentrations? Please explain with the ...
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Is standard gibbs free energy change of a reaction independent of pressure? [duplicate]

In my textbook, to show that Kp(equilibrium constant) is independent of pressure they have used the equation (delta G = RTln Kp) and the author says that since delta G for a reaction is independent of ...
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How is silicic acid formed?

My book gives the following reaction: $$\ce{SiCl4 + H2O -> HCl + Si(OH)4}$$ Since equilibrium favours the formation of weaker acids. How is this reaction able to proceed if a strong acid like HCl ...
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what happens if you add the concentration of BOTH product and reactant at equilibrium

It is seems obvious that if you increase the REACTANT ONLY, the position of Equilibrium will move to the product side. Thus making more product if you measured it again in the second equilibrium. ...
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What causes an equilibrium? [closed]

Certain reactions are reversible and some are irreversible. I know that equlibrium will exist if the reaction is reversible. But what causes the reversible reaction? For example $\ce{NaOH}$ and $\ce{...
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Is it possible to calculate a maximum pressure attainable with a soda vinegar reaction? [closed]

Given Le Chatelier's principle, there must be a peak pressure of $\ce{CO2}$, at which, under room temperature, the reaction of soda with vinegar would stop? $$\ce{Na2CO3 + 2 CH3COOH -> CO2 + 2 ...
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How do I find the pressure that would be present in carbon dioxide for this problem?

Problem: For the reaction below, Keq = 0.0064 (at 825C). If you place 12.011 g Carbon and 5 atm pressure of water vapour in a 2.0 L reaction flask, calculate the pressure of carbon dioxide gas that ...
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Pure Solids and Liquids not considered in equilibrium constant expression

I am a high schooler and recently we learned Equilibrium. We were taught that the concentration of pure solids and liquids are taken as 1 for the equilibrium concentration as their concentration ...
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How does it affect the equilibrium expression if the concentration of any component remains the same?

I am a high school student and I am very confused in Equilibrium expression, My confusion is that "Why we don't write concentration of solids and pure liquids in equilibrium expression?" ...
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Can I mix pressures and concentrations when finding equilibrium constant? [duplicate]

In order to find the equilibrium constant (or reaction quotient) I know I can find the value as the products over reactants raised to coefficient exponents. But, in all of the problems I have had to ...
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29 views

Equilibrium reaction where the number of moles of reactants and products are the same [closed]

Le Chatelier's principle says that for an equilibrium reaction where all reactants and products are gases a change in pressure will change the number of moles of the product such to counteract the ...
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A problem regarding solubility and concentration

A solution is $\pu{0.10 M}$ $\ce{Ba(NO3)2}$ and $\pu{0.10 M}$ $\ce{Sr(NO3)2}$. If solid $\ce{Na2CrO4}$ is added to the solution, what is the $\ce{[Ba+]}$ when $\ce{SrCrO4}$ begins to precipitate? $\...
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Why doesn't separating the layers change the equilibrium point?

I'm following this tutorial for synthesizing esters. I don't understand why adding water to the separation funnel doesn't push the equilibrium reaction point back to the left, or why draining it doesn'...
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Will a salt dissociate completely in water to give free ions?

I was reading salt hydrolysis of a salt made from strong acid and weak base. I came across the hydrolysis of $\ce{NH_4Cl}$. These reactions were mentioned $$\ce{NH_4Cl + H_2O<=>NH_3 + HCl \tag{...
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What makes concentrated aqueous solutions of aluminium nitrate and aluminium chloride suitable to dissolve noble metals, specifically gold? [closed]

Aluminium nitrate is a strong oxidising agent and aluminium chloride acts as a Lewis acid. Also these solutions are claimed to have the abilities of aqua regia and therefore can dissolve noble metals. ...
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Does the acid dissociation constant takes hydrogen ions from water into account?

For the dissociation of a weak acid: $$\ce{HA(aq)<=>H+ + A-}$$ To calculate $\mathrm{pH}$ of a weak acid, we use the expression: $$K_\mathrm{a}=\ce{\frac{[H+] [A-]}{HA}}$$ The $\ce{[H+]}$ has ...
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Calculations of concentrations in two different equilibria

I'm a high school student, and I'm learning about acid dissociation equilibrium. I wanted to make the idea of Le Chatelier's principle rigorous in math, so I decided to take to it with some calculus. ...
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Will equilibrium ever establish if one of the products starts to disassociate?

When $\ce{N_2O_5}$ is heated at a certain temperature, it disassociates as $$\ce{N_2O_5 (g)<=>N_2O_3 (g) + O_2 (g); K_c = 2.5}$$ At the same time $\ce{N_2O_3}$ also decomposes as $$\ce{N_2O_3 (g)...
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Why isn't standard Gibbs energy zero at equilibrium?

At equilibrium, everything that $G$ depends on is constant. The Gibbs' free energy may have been given to you without really emphasizing that it is actually a function of temperature, pressure, and ...
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Entropy of reaction from these givens?

Reaction that happens at 380 Kelvin $\begin{align} \Delta S^\circ _{sys} &=\pu{-130 J/molK}\\ C_p(\ce{C2H4})&=\pu{43.6 J/molK}\\ C_p(\ce{C2H5OH})&=\pu{65.9 J/molK}\\ C_p(\ce{H2O})&=\pu{...
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Equilibrium constant and stoichiometry [duplicate]

In the expression of equilibrium constant, each concentration term is raised to the power of their stoichiometric coefficient. But this could affect the equilibrium constant. For example, we can write ...
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Can reversible reactions proceed by different mechanisms in the forward and reverse directions? [closed]

It seems odd to me that this would be the case, but it also seems odd that it wouldn't. Imagine a mechanism for a (forward) reaction that includes a slow reversible step and a fast irreversible step: ...
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Active mass of solids shouldn't necessarily be unity [duplicate]

I've read that active mass of solids and pure liquids is considered unity. I'm absolutely sure there is some misunderstanding. I know that concentration of solids doesn't change during the course of ...
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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: $$\ce{A + B <=> C}$$ Where we ...
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Working out energies of hydrogen bonds by comparing chemical potential of vapour and condensed phase - equation derivation

I want to ask a question about working out the energy of a hydrogen bond between two water molecules, $w_{AA}$ using the chemical potentials of vapour and condensed phases. I was reading K. Dill, ...
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Brownian motion modeling of surface reaction

I am interested in simulating a reaction-diffusion system, where particles subjected to Brownian motion can react when they reach a specific surface. The reaction is simple: A $\rightleftharpoons$ B ...
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Calculating rate constant from equilibrium constant

I'm trying to determine the forward rate for the Haber Process, but can't find the rate constant. I have the equilibrium constant, but to my knowledge this only gives me the ratio of the rate constnts ...
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how to derive equilibrium concentrations from initial conditions for mass action reactions?

I am reading a tutorial on biochemical reactions and mass action kinetics (https://www.math.utah.edu/~keener/books/control.pdf, pp. 1-2) and would like to derive an analytic solution to confirm ...
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Acorrect range of concentrations for the reactants in the equilibrium reaction

What would be a correct range of concentrations for the reactants in the equilibrium reaction, $\ce{Fe^3+(aq) + SCN-(aq) <=> FeSCN^2+}$? For a Chemistry project I am measuring the effects of ...
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Dissociation constant for Indicators

So I came across a question which asked to calculate the $\mathrm{pH}$ at which an indicator of given $\mathrm{K_{a}}$ would change colour. The solution was given in the following way Since when the ...
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Glucose and related aldohexoses are interconvertible with a little base. Does anybody know how much of each sugar is present at equilibrium?

If you add NaOH to D-glucose in water, a mixture of almost all aldohexoses will arise over time, including mannose and fructose. I wonder how much of each will be present and what could explain the ...
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Wiki’s explanation of the rate of chemical reaction [closed]

Could you please help me understand the Wiki’s explanation of the rate of chemical reaction? It says: the rate of the chemical reaction is directly proportional to the product of the activities or ...
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Why value of K(equilibrium constant)becomes squared when we multiply the equation with 2 when its value solely depends on temperature?

We know that value of equilibrium constant for a particular reaction is independent of concentration of the reactants with which we start or the direction from which equilibrium is approached But when ...
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Why is vapor pressure constant at boiling point?

At non-boiling point, I understand that when you add heat, temperature increases and also the amount of gas increases, so by using $PV=nRT$ at constant volume, the increase in $n$ and $T$ would ...
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Calculating numbers of moles at equilibrium given the volume of mixture and initial concentration of reactants [closed]

The equilibrium between three substances, A, B and C Is shown below. $$\ce{A(g) + B(g) <=> C(g)}$$ Initially there were $\pu{0.1 mol}$ of A and $\pu{0.2 mol}$ of B in the reaction mixture. A and ...
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Is is valid to compare reaction quotient to $K_p$ as well as $K_c$?

Can I use the reaction quotient compared to $K_p$ to answer the following question? The solid $\ce{XY}$ decomposes into gaseous $\ce{X}$ and $\ce{Y}$: $\ce{XY(s) <=> X(g) + Y(g)}$ with a $K_p = ...
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What does enthalpy of formation at room temperature mean?

$\ce{AlCl3}$ has a standard enthalpy of formation some high negative value at $298\ \mathrm K$ $(-705.63\ \mathrm{J/mol})$. It means it's an exothermic reaction i.e will release heat. But my question ...
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Driving force in distillation

If the pressure is lowered in a distillation column, then the equilibrium curve will move further away from the diagonal (bulge out more) in an equilibrium diagram. This leads to a decrease in ideal ...
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What happens when the amount given doesn't allow for equilbrium to be achieved in a reaction?

The reaction $$\ce{A.3H2O(s) <=> A.H2O(s) + 2H2O (g)}$$ has a $K_p = \pu{400 mmHg2}$ One millimole each of $\ce{A.3H2O}$ and $\ce{A.H2O}$ are taken in a $\pu{1 liter}$ container at $\pu{300 K}$ ...
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Opposite effects of Le Chatelier's Principle

How does Le Chatelier's Principle deal with a change in reaction conditions which can simultaneously effect the equilibrium in opposite ways. For example, here's the equation for the conversion of $\...
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Calculating the number of volatile molecules in a container of known volume [closed]

Is it possible to calculate the number of volatile molecules (so only those in the gaseous phase) in a container of known volume, if the vapor pressure of the compound is known? So for example, if you ...
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How does current start to flow when galvanic cell is first connected?

Using the Daniell Cell as an example, where in the steady state we expect zinc to be oxidised and copper to be reduced spontaneously due to the overall reduction in Gibbs free energy, how does the ...
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Effect of adding pure solid/liquid in heterogenous equilibrium

QUESTION Consider the following reaction as an example: $$\ce{NaNO3(s) <=> NaNO2(s) + 1/2O2(g)}$$ Once this reaction has achieved equilibrium and then if we added pure $\ce{NaNO3}$ to this ...
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Why isn't auto ionisation of water considered when we find the pH during salt hydrolysis?

$\ce{H+}$ concentration from the auto-ionisation of water is $10^{-7}$ If we have $\ce{HA}$ as weak acid and $\ce{BOH}$ as weak base having $\mathrm pK_\mathrm{a} = 3.2$ and $\mathrm pK_\mathrm{b} =3....
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Comparison of the solubility of lead(II) iodide in water and in lead(II) nitrate solution [closed]

Solubility of $\ce{PbI2}$: Is $\ce{PbI2}$ more soluble in $\ce{H2O}$ or in an aqueous solution of Lead(II) nitrate? $K_\mathrm{sp} (\ce{PbI_{2}})=8.7\times 10^{-9}$ I'm not very good in Chemistry, I ...
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Why does the water dissociation constant Kw remains constant? [closed]

At $\pu{25 ^\circ C}$ at equilibrium the value of $K_\mathrm{w}$ is $\pu{1\times 10^{-14} M}$ and the concentration of $\ce{H+}$ and $\ce{OH-}$ is equal i.e. $\pu{1\times 10^{-7} M}$. Now if we add $\...
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Is this buffer possible?

Question Can a buffer solution be obtained by mixing- A) $\ce{NH4Cl}$ + $\ce{CH3COONa}$ B) $\ce{CH3COOH}$ + $\ce{NH4OH}$ My Thoughts I know that a buffer solution can be obtained if we mix a acid and ...
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What is an alternate way of preparing a sodium hydrogen phosphate/sodium dihydrogen phosphate buffer through titrating an acid with a strong base?

So my friend and I are stumped. This is in the context of achieving the sodium hydrogen phosphate/sodium dihydrogen phosphate buffer by titrating the acid with a strong base. My friend says the answer ...

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