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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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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Pls answer equilibrium question about Le Chatelier principle [duplicate]

If temperature is increased then according to le chatlier principle the reaction will move in the direction where energy is absorbed. this I can understand ,but there is also another fact ...
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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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140 views

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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76 views

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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Ksp Equilibrium determining Mass [closed]

Suppose that 50.0mL of 0.100M AgNO3 were added to 50.0mL of 0.5M NaCl. What is the weight of AgCl will be formed? What would be the final concentration of the Ag+ ions? Hey guys. I am currently ...
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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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Increasing temperature in system of dynamic equilibrium

According to the article Summary of Le Chatelier's Principle on dynamicscience.com.au, for the process $$\ce{N2(g) + 3 H2(g) <=> 2 NH3(g)}\quad ΔH = \pu{-92 kJ/mol}$$ the forward reaction is ...
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Dynamic equilibrium in unsaturated solutions

One standard definition of equilibrium in beginner chemistry is that for a reversible reaction, (dynamic) equilibrium has been achieved when the rate of the forward and backward reactions are equal. ...
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Rate Equation of Chemical Traffic Light (NaOH + Glucose + H20 + Indigo Carmine)

I am trying to find the Rate Equation of the Chemical Traffic Light Experiment. Wikipedia says the Blue Bottle Experiment (similar, but uses a different dye) has the following orders: The reaction ...
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Ka for reaction from tables [duplicate]

For the reaction below: NH4+ + H2O -> NH3 + H30+ I have the following values from a table to use: And in the solution manual they tell me to use the Ka for this reaction. Why is this? Why do we ...
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What is the difference between chemical equilibrium and dynamic equilibrium?

Is chemical equilibrium and dynamic equilibrium the same thing? Both point to the reversible reactions and no net changes in the concentrations of product and reactant. Dynamic equilibrium from ...
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Thermochemical data for thiocyanatoiron(III) ion

I am currently writing a lab report about the formation constant of $\ce{FeSCN^2+}.$ All I could find online was a formation constant at $\pu{25 °C}$ $(890),$ which was 70% higher than the ...
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Chemical equilibrium [duplicate]

When calculating equilibrium constant with partial pressures if there is a solid involved should we consider it in the total number of moles in mole fraction?
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What exactly causes equilibrium to shift when pressure is decreased? [duplicate]

Take the reaction: $$\ce{N2(g) + 3 H2(g) <=> 2 NH3(g)}$$ If pressure is decreased, equilibrium shifts to the left because it has more moles. I understand the basics of why this is, i.e. due to ...
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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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Equilibrium of an electrochemical cell [closed]

I am quite new to the field. So try to figure out what is meant by the equilibrium state of an electrochemical cell? Is it, where both half cells passing the same number of electrons to either side? ...
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Gibbs energy derivative vs equilibrium for aqueous reaction

I am trying to find the Gibbs-energy equilibrium for the reaction $$\mathrm{A}+\mathrm{B}\rightleftharpoons\mathrm{C}.$$ According to most sources the equilibrium concentrations in an ideal solution ...
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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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71 views

How is a phase equilibrium defined for a one-component system?

A question on this site asked whether a one-component system is at equilibrium when melting or boiling, and the disparate answers were somewhat dependent on the definition of phase equilibrium. ...
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3answers
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melting and boiling …really equilibrium? [closed]

Why are melting and boiling considered equilibrium processes even though the amount (concentration) of both phases keep changing i.e from solid to liquid and so on?
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Azeotropic Distillation - Am I interpreting this VLE diagram correctly?

I've been looking at ways to re-concentrate a formic acid-water binary mixture with the VLE diagram below. Am I correct in saying that to concentrate a solution of say , 40% formic acid by weight I ...
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Spectroscopic Determination of an Equilibrium Constant [closed]

I got values of $\pu{5.0E-4}$, $\pu{2.5E-4}$, and $183$ for the following problems. However, these seem to be inaccurate and I'm not sure what to do. Here is the procedure: Obtain 6 disposable ...
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Gibbs free energy of phosphorus pentachloride decomposition reaction

The equilibrium constant at $\pu{227 °C}$ for the equation $$\ce{PCl5(g) <=> PCl3(g) + Cl2(g)}$$ is $K_p = \pu{4.50E3 bar}.$ Calculate the value of $Δ_\mathrm{rxn}G^\circ$ at $\pu{227 ...
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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 $\mu_i^{vap} = \mu_i^{liq}$. ...
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Calculating partial pressure of carbon monoxide

$\ce{ZnO}$ is exposed to pure $\ce{CO}$ at $\pu{1300 K}$ and the equilibrium $$\ce{ZnO(s) + CO(g) <=> Zn(g) + CO2(g)}$$ is then established at $\pu{1 atm}$ pressure. The density of the ...
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Can the rate of reaction of a Voltaic/Galvanic cell be determined theoretically?

I am conducting a chemistry practical in which I measure the voltage of a Zn-Cu Voltaic cell over time. Assuming that the surface area of the electrodes are known, concentration of reactants are ...
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Why does an electron lose energy so that it falls back to a lower energy state than just stay at the higher energy state?

Suppose an electron in the 2nd shell gets excited and jumps to the 4th shell. Shouldn't the electron then exist in an unstable equilibrium in the 4th shell, than lose energy and drop down to the 2nd ...
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What is the true meaning of Gibbs energy and chemical potential?

After doing some research and reading I found some problems which I will try to state as clearly as possible. The definition of Gibbs Free Energy says "the greatest amount of mechanical work which ...
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How can batteries reach equilibrium if the reactions are irreversible?

My book says that the batteries we have considered so far (Daniell cells) have a low life span because they reach equilibrium too quickly. In the next paragraph, it states they are also made by ...
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Does salt hydrolysis takes place in buffer solution? [closed]

I am a bit confused whether hydrolysis of salt takes place in buffer solutions because the books which I read doesnt consider them.But I think since weak base or weak acid salt is present hydrolysis ...
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Equilibrium pressure

Ammonium carbamate dissociates as follows: $$\ce{NH2COONH4(s)<=> 2NH3(g) + CO2(g)}$$ The value of $K_p$ for this reaction is found to be equal to $\pu{2.92 \times 10^-5 atm^3}$. If ...
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When pH > pKa and when pH < pKa and the effectiveness of buffer solutions

I understand that when $\mathrm{pH}= \mathrm{p}K_\mathrm{a}$, the buffer solution will be at its maximum capacity, and there will be equal concentrations of the acid/conjugate acid and the base/...
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Why does reducing the pressure in an equilibrium reaction favour the side with more moles of gas?

I was trying to explain it in terms of reaction rates and such; more than just 'Le Chatelier's principle states ...', but I can't figure out the underlying reason as to why. I can explain why for ...
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Equilibrium Constant & Rate-Determining Step

My first language is not English, so there might be some parts where it's hard to read. Sorry in advance. I have some questions regarding the derivation of the equilibrium constant and the rate-...
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Finding ionic radii from solubility data and density

$\pu{5.35 g}$ of a salt $\ce{ACl}$ is dissolved in $\pu{250 ml}$ of solution. The $\mathrm{pH}$ of the resultant solution was found to be $4.85.$ Find the ionic radius of $\ce{A+}$ and $\ce{Cl-}$ if ...
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Genuine confusion about the equilibrium constant [closed]

I gather that the equilibrium constant K = 1 implies that, at equilibrium, neither the forward nor the backward reactions are thermodynamically favoured. But if pressure of the system increases and ...
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Mathematical justification for Le Chatelier's principle

At equilibrium $$ \begin{align} K &= \exp\left(\cfrac{TΔS^\circ - ΔH^\circ}{RT}\right)\\ ⇒ \frac{\mathrm d \ln K}{\mathrm dT} &= \frac{ΔH^\circ}{RT^2} \end{align} $$ If enthalpy change is ...
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When is the concentration in which you put into the equilibrium constant equal to 1 for solids and liquids?

There are many websites which states that pure liquids and solids have a concentration equal to one, but for some equations they are not! How do you explain the difference for this equation? For the ...
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How to confirm experimentally that a hemi-acetal compound has formed?

I have read that under mildly acidic or alkaline conditions alcohols can attack aldehydes/ketones to produce hemi-acetals. But the reaction is reversible, so the reactants and the hemia-cetal are in ...
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How do I find pH of a mixture of weak acids? [duplicate]

Suppose that we are given two weak bases $\ce{HA_1}$ and $\ce{HA_2}$. We are also given the $K_\ce{HA_1}$ and $K_\ce{HA_2}$. How can we calculate the $\mathrm{pH}$ of the mixture?
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Defining the position of equilibrium

I've read quite a few other answers on this site such as this one, but can't quite seem to understand fully yet. Say we have a container with gases reacting such that the number of moles on both ...