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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equilibrium reactions [closed]

How will the equilibrium of following reactions be affected 1) N2(g) + O2 (g) ⇄ 2NO(g); 2) 4HCl(g) + O2(g) ⇄ 2Cl2(g) + 2H2O(g) a) by rise of pressure; b) by decrease of oxygen concentration? Explain ...
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Description of a van't Hoff apparatus

A "van't Hoff apparatus" is mentioned as a means of performing a reaction involving gases in a reversible manner, for instance here. Unfortunately I have been unable to find a description of such a ...
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Is Gibbs energy minimized for processes at constant temperature are pressure only?

I've had this doubt for quite a while, This link https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Map%3A_Physical_Chemistry_for_the_Biosciences_(Chang)/04%...
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Le Chatelier's Rule: Relationship between Pressure and Reaction when moles of reactant and products are the same

Consider the equation: $\ce{H2(g) + CO2(g) <=> H2O(g) +CO(g)}$ Indicate how each of the following changes affects the amount of each gas in the system: (a) Decrease in the volume of the ...
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Chemical Equilibrium - Le Chatelier's Principle, Change in Volume

Question: Consider the following reaction at equilibrium at a total pressure that we will call $P_1$. $$\ce{2 SO2(g) + O2(g) <=> 2 SO3(g)}$$ Suppose the volume of the system is ...
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Reaction of Fe2+ and S2- to form FeS

Consider this reaction: $$\ce{Fe^{2+} (aq) + S^{2-} (aq) <=> FeS (s)}$$ The equilibrium constant for the reaction is $1.6 \times 10^{17}$ at $\pu{298K}$. If equal volumes of $\pu{0.06 M}$ ...
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Proof for Arrhenius equation [closed]

The Arrhenius equation states that: $$k=A\mathrm e^{\frac{-E_\mathrm a}{R T}}$$ What is the mathematical proof for this equation?
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Equilibrium constant independence from pressure for gaseous reactions [closed]

Why the equilibrium constant for a homogeneous gaseous reaction is not affected by pressure (nor volume) but only by temperature, if for gases temperature depends on pressure according to the ideal ...
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1answer
53 views

How to derive the steady-state solution for simple two-step reaction with differential equations? [closed]

Consider this simple two step reaction, a variant of a Michaelis-Menten type of problem, where $\ce{A}$ and $\ce{B}$ reversibly bind to make $\ce{AB}$, and $\ce{AB}$ and $\ce{C}$ reversibly bind to ...
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Is the evaporation (liquid to gas conversion) of ethanol dependent on how full you fill it up in a sealed bottle?

It seems intuitive to think that in a bottle (which is air-tight), if you fill up ethanol (or any other volatile liquid) to very full extent, thereby leaving very little headspace, the amount of ...
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Temperature in Le Chatelier's principle [duplicate]

Suppose I have a reversible reaction and the forward reaction is endothermic. Now if I increase the temperature, the rate of the forward reaction will increase but as I increase the temperature, the ...
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58 views

Why is the voltage produced by a voltaic cell affected by temperature as described by the Nernst Equation?

I understand why changing the concentrations of the electrolytes in a voltaic cell affects the voltage. Given a zinc-copper cell for example, if I were to increase the concentration of the zinc ...
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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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Would the same equilibrium concentration of carbon dioxide, carbon monoxide and oxygen always result for a given initial atomic carbon fraction?

Chemistry SE Question: Starting with a gas mixture of some combination of gases containing carbon and oxygen with a total carbon atomic fraction $f$, would it always reach the same equilibrium ...
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Help required with calculation of reaction rate for a chemical reaction

*Note: This is not a homework problem but something related to my research! Thanks I'm simulating a metal droplet suspended in a reactive medium. The droplet tends to react with the injected gas as ...
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How to find the value of $K_c$?

This is part of my homework. Given the chemical equation : $$\ce{Sb2S3_{(s)} + 3H2_{(g)} <=>2Sb_{(s)} + 3H2S_{(g)}}\text{ }K_{p}=0,429\text{ at }713\text{K}$$ What is the value of $K_c$ ...
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What exactly is the requirement (in terms of saturation) for a reaction to be at equilibrium? [closed]

A saturated solution is a solution that contains the max amount of solute able to be dissolved. However, can't a solution still be at equilibrium if you add more solute to a saturated solution as long ...
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1answer
37 views

Can rate constant for forward reaction be equal to rate constant for backward reaction? [duplicate]

For a particular reaction, can we have $K_c = 1$? My confusion arised when I was studying the effect of temperature on $K_c$ . I see that the temperature must affect forward and backward rate ...
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Hydrogen disulfide heterogenous equilibrium

I have been struggling with the following problem for quite a while: I was able to calculate the Gibbs free energy and the equilibrium constant, using the formula $$ΔG = -RT\ln K$$ and ...
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45 views

Delta G in an equilbrium reaction(forward and backward)

Consider a reaction say $$\ce{A + B <=> C + D}$$ Now $\Delta G$ for the forward reaction is: $$\Delta H - T\Delta S$$ For the backward reaction $\Delta H$ and $\Delta S$ are clearly the same ...
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Equation of water at triple point

I was thinking about what exactly happens at the triple point of water, and what could be the effect of adding solutes/solvents. I feel we can represent the triple point using the following ...
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how to Find $P_{tot}$ Given that $K_p = 28.5$ and the partial pressure at equilibrium

I have the equilibrium equation : $4KO_2{_{(s)}} + 2CO_2{_{(g)}} \ce{<=>} 2K_2CO_3{_{(s)}} + 3O_2{_{(g)}}~~k_p = 28.5 ~at ~25C$. Given that The partial Pressure of $CO_2$ is $0.191~atm$ at ...
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Deprotonated form of phenolphthalein

The wikipedia page states clearly that the coloured form of phenolphthalein is the one with two protons removed. What is the evidence that phenolphthalein loses both protons in basic solution? And ...
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How to account for the common ion effect on osmolarity quantitatively?

In adjusting the osmolarity of a solution of Benzalknonium Cl, Disodium Editate, and Disodium borate/boric acid buffer to be isotonic (about 290 mOsm), the addition of NaCl showed unexpected behavior, ...
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38 views

How to explain that an increase in temperature favours an endothermic reaction?

I'm trying to explain how a change in temperature favours an endothermic/exothermic reaction from a collision theory point of view, but I'm not really familiar with the concept just yet. For an ...
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1answer
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Question about change in pressure and change in temperature for system at equilibrium

I was reading my Chemistry textbook and I noticed that it stated that for a system at equilibrium: At constant temperature, reducing the volume of gaseous equilibrium mixture causes the system to ...
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30 views

Is there a name, or any specific jargon for a precipitation equilibrium involving a solid reactant?

Let's say you have some ions in solution, for example Na+(aq) and OH-(aq), and some partially dissolved solid, MgCO3(s), Mg+2(aq) and CO3-2(aq), which precipitates Mg(OH)2(s) until equilibrium. So ...
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Will NaF + CaCO3 precipitate much CaF2?

If I mix sodium fluoride, calcium carbonate powder, and water, under what conditions (if any) would there be an equilibrium? I.e. assume we start out with fully dissociated $\ce{Na+(aq) + F-(aq)}$, ...
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Kinetics of converting a water + heavy water mixture to HDO

Imagine an initial 50%-50% mixture of normal ($\rm H_2 \rm O$) and heavy water ($\rm D_2 \rm O$). I think, simply mixing them, the result will exponentially converge to an equilibric state, where ...
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How to manage complex equilibria when studying a mecanism?

Consider a complex multistep reaction mechanism with several intermediates. There are multiple possible pathways as well as equilibria in solution. One wants to study the reaction mechanism using ...
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In reversible processes in dynamic equilibrium why do we only see the products and not the reactants?

If both forward and backward reaction rates are equal why is it that only the products are visible to a naked eye?
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Finding Ka of a monoprotic weak acid from pH and concentration of added sodium salt

A solution of $\pu{0.36 M}$ of the sodium salt of a generic monoprotic weak acid $\ce{HA}$ has a $\mathrm{pH}$ value of $8.782.$ $K_\mathrm{a} = ?$ Why doesn't the following formula work in this ...
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Modifications and alterations in the state of chemical equilibrium

Let us consider that we have a mixture of gases, considered ideal, that is in balance. Like, for example, $$3\ce{NO} (g) \rightleftharpoons \ce{N2O} (g) + \ce{NO2}(g)$$ If we consult the ...
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pH of amphoteric species

For a solution of $\ce{HA-}$, I have seen the following approximations for the $\mathrm{pH}:$ $$\mathrm{pH} = \frac{1}{2}(\mathrm{p}K_\mathrm{a1} + \mathrm{p}K_\mathrm{a2})\tag{1}$$ $$\mathrm{pH} = \...
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Has anyone encountered the use of Omega to represent equilibrium?

One of my lecturers last year (a pharmacologist by training) used the symbol $\Omega ^m$ as a shorthand for equilibrium. He implied it was common practice but I've never come across it elsewhere. I ...
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How to simplify these system of equilibrium equations

What is the pH when $0.025$ mol $\ce{NiCl2}$ is added to $\pu{1.00 L}$ of a $\pu{0.100 M}$ solution of $\ce{HCN}$, if the formation constant for $\ce{Ni(CN)4^2-}$ is $K_f=\pu{1.0e22}$, and the $K_a$ ...
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Determining relative changes in a generic reaction

I'm an electrical engineer by trade and I am trying to solve a problem I found in some old course notes. Given is a reversible, homogeneous reaction: $\ce{ A + 2B <=> C + 3D }$ A solution of ...
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How does LeChatelier’s principle (which makes qualitative predictions) relate to the quantitative changes observed when an equilibrium is disturbed?

Le Chatelier formulated his principle in 1884; it predicts the direction in which equilibrium is re-established after it has been disturbed by an external cause. How does this qualitative principle ...
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Finding the concentration of each ion in saturated solution of lead(II) hydroxide

Question If the solubility of $\ce{Pb(OH)2}$ is $\pu{0.155 g/L},$ then the concentration of each ion in a saturated solution of $\ce{Pb(OH)2}$ is A. $[\ce{Pb^2+}] = \pu{0.155 g/L}$ and $[\ce{...
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How to calculate the amount of sodium sulfate needed to lower the silver ion concentration of a saturated silver sulfate solution?

How many moles of $\ce{Na2SO4}$ we have to add into a saturated $\pu{0.5 L}$ solution of $\ce{Ag2SO4}$ so that the concentration of $\ce{Ag}$ is $\pu{4.0 \times 10^-3 M}$? ($K_\mathrm{sp} = 1.4 \times ...
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Le Chatelier's principle and van 't Hoff equation

When temperature is increased, then according to Le Chatelier's principle the reaction will move in the direction where energy is absorbed. I can understand this, but there is also another fact that ...
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Use of Concentration for pH

When we find the pH of a solution, do we use normality or molarity? My teacher said that if the compound is present by itself, we can use normality but in all other cases we should use molarity. Can ...
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Calculating pH of rain water

The concentration of $\ce{SO2}$ in the atmosphere over a city on a certain day is $\pu{10 ppm}$. Given that solubility of $\ce{SO2}$ in water is $\pu{1.3653 mol L-1}$ and $\mathrm{p}K_\mathrm{a}$ of $\...
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Calculating equilibrium concentrations of silver and halide ions

$\pu{500 ml}$ of $\pu{0.01 M}$ $\ce{AgNO3}$ is mixed with $\pu{500 ml}$ of solution containing $\pu{0.1 M}$ $\ce{NaCl}$ and $\pu{0.1 M}$ $\ce{NaBr}$. $K_\mathrm{sp}$ of $\ce{AgCl}$ is $10^{-10}$ and $...
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Is chromate a suitable indicator for the titration of Ag⁺ with Cl⁻?

To titrate $\ce{Cl-}$ with $\ce{Ag+}$ we use chromate $\ce{CrO4^2-}$ as an indicator. The titration reaction is: $$\ce{Ag+ + Cl- <=> AgCl}\tag{R1}$$ $$K_1 = \frac{1}{K_\mathrm{sp}(\ce{AgCl})} =...
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Why does a reaction move both forward and backward in dynamic equilibrium? [closed]

As a kid I never imagined equilibrium to be a state where both forward and backward reactions keep taking place. Although, by seeing one cannot tell. Why is it that both forward and backward reactions ...
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If volatility depends on intermolecular forces, then why in Raoult's law, two substances have different volatility?

I have a doubt, Ideal solutions are solutions where intermolecular forces between solute-solute and solvent-solvent are nearly equal to solute-solvent. Since intermolecular forces between A-A = B-B, ...
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Calculating partial pressure with 3 equilibrium equations [closed]

So my friend had sent this question to me some days ago and it seems I still am not able to solve it. I am confused whether the amount of A that dissociates in the first equation would account for the ...
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Ligand substitution reaction in coordination compounds

I know that the following substitution reaction can take place: $$\ce{[Cu(H2O)4]^2+ (aq) + 4NH3 (aq) -> [Cu(NH3)4]^2+ (aq) + 4H2O (l)}$$ This is because ammonia is a stronger ligand than water. ...
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What is wrong in this argument that dG must always be zero?

Under constant temperature and pressure, the change of the Gibbs free energy can be written as $$\mathrm dG_\textrm{sys} = \mathrm dH_\mathrm{sys} - T\,\mathrm dS_\mathrm{sys}$$ And in the textbook ...

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