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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1answer
67 views

Effect of inert gas on Q

Adding an inert gas will not affect Q if that reaction is held at a constant volume. But, if the reaction is held at constant pressure, then adding inert gas will change Q bc the partial pressures of ...
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165 views

Who developed the concept of ICE tables?

Many general chemistry courses (at least in the US) or online tutorials solve problems of chemical equilibrium by using ICE (sometimes RICE) tables, which track how the moles of reactants and products ...
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Determining Kc for the equilibrium involving iron thiocyanate using spectrophotometric data

$$\ce{Fe^3+(aq) + SCN-(aq) <=> [Fe(SCN)]^2+(aq)}$$ $\pu{12.0 mL}$ of $\pu{0.00110 mol L-1}$ $\ce{Fe^3+}$ was added to $\pu{6.00 mL}$ of $\pu{0.00140 mol L-1}$ $\ce{SCN-}$. The absorbance of the ...
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Which acid/base does a strong base/acid react when added to a buffer solution?

I'm in high school chemistry and just learning about buffer solutions. For example, given a buffered solution of $\ce{CH3COOH}$ and $\ce{NaCH3COO}$ with $K_a = 1.8 \times 10^{-5}$, we might want to ...
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417 views

Calculating the pH of a buffer made by a diprotic acid and its double salt

The concentration of the diprotic acid (tartaric acid) will be constant at $\pu{ 0.1 M}$. I want to find the concentration of its double salt (potassium sodium tartrate) needed to create a buffer of $\...
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118 views

Please explain the mystery of the equilibrium constant expression for chemical reactions [closed]

Given a reversible chemical reaction, e.g. $$\ce{CuCl4^2-(aq) <=> Cu^2+(aq) + 4Cl-(aq) + \text{heat}}$$ occurring in a medium, the equilibrium constant is defined as $$K = \frac{[\ce{Cu^2+}][\ce{...
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41 views

Equilibrium Constant and Reaction Mechanism [duplicate]

How is it possible for the equilibrium constant to not depend on a reaction's mechanism? For the elementary reaction $$aA + bB \rightleftharpoons dD + eE$$ I understand that the rate of the ...
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841 views

Equilibrium constant for esterification process

Teacher told us that the concentration term for pure liquids and solids is always $1$. But online I found this reaction: $$\ce{CH3COOH(l) + CH3CH2OH(l) <=> CH3COOCH2CH3(l) + H2O(l)}$$ ...
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339 views

How to calculate the equilibrium constant for nitrogen, hydrogen, and ammonia?

$\pu{2 mol}$ of $\ce{N2}$ is mixed with $\pu{6 mol}$ of $\ce{H2}$ in a closed vessel of $\pu{1 L}$ capacity. If $50\%$ of $\ce{N2}$ is converted into $\ce{NH3}$ at equilibrium, what is the value of $...
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1answer
40 views

Should I include ions from the solvent in solubility product constant calculations?

I'm trying to determine the Solubility Constant $K_\mathrm{sp}$ of $\ce{Ba(NO3)2}$ dissolved in nitric acid solution $\ce{HNO3}$ from experimental data. $\ce{HNO3}$ will be mostly dissociated so ...
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297 views

Is a discharged battery in a state of chemical equilibrium?

A reaction that has reached chemical equilibrium no longer shows changes in reactant and product concentrations, but forward and reverse reactions are still going on. I'm confused whether a completely ...
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1answer
1k views

What is the concentration of H2 for the equation H2+I2=2HI if the equilibrium constant is 64 and the initial concentrations are both 1.9

So for this, I set up the equation = $$64= \frac{(x)^2}{(1.9-x)^2}$$ I took the sqrt of both sides and got $$8=\frac{x}{(1.9-x)}$$ So then I did $$8(1.9-x)=x$$ And simplified I got $$15.2=9x$$ ...
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2answers
681 views

Gibbs free energy in standard state vs. equilibrium

I have a problem with the definition of the standard Gibbs energy and its connection to the equilibrium constants. I think, that I've basically understood what the different equation mean but there ...
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385 views

Conversion of graphite into diamond [duplicate]

The standard state Gibbs free energies of formation of C(graphite) and C(diamond) at $T = \pu{298 K}$ are $\pu{0 kJ mol-1}$ and $\pu{2.9 kJ mol-1}$, respectively. The conversion of graphite [C(...
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161 views

Why neglecting OH Ions from charge balance?

I have a problem, in which the concentration of $\ce{Ca^{2+}}$ ions in water should be related to the partial pressure of $\ce{CO2}$ (assuming the water is an open system and in equilibrium with ...
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2answers
93 views

Ionic equilibrium between multiple ions

This is a question from IIT-JEE 1993: For the reaction $$\ce{[Ag(CN)2]^- -> Ag^+ + 2CN^-}$$ the equilibrium constant at $\pu{298 K}$ is $\pu{4e-10}$. The silver ion concentration in a ...
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1answer
96 views

Drug pH and pKa known, is it an acid or a base? [closed]

I want to answer the question if a drug which is analysed for pH and pKa is ionised or not ionised in a cow stomach with a pH of 6. The drug has a pH of 8,52 and a pKa of 8,78. Since the pH is 8,52 ...
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Intuition for why catalyst affects both forward and reverse reactions equally?

I have looked for quite a long time on the site however all the answers involve mathematical explanations involving Arrhenius's equation. I would really like an intuitive reason (or one using ...
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75 views

Effect of solid in equilibrium

CaCO3 (s) = CaO (s) + CO2 (g) We know that pure solids quantity doesn't affect the position of equilibrium. But the application of pressure in gas does. If we add CaCO3 in the closed system, the ...
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1answer
369 views

How does monoethanolamine (MEA) increase pH?

I know pH of a solution increases with increase concentration of $\ce{OH-}$. I'm wondering: when adding MEA, is the $\ce{OH-}$ group from the MEA breaking off, or is it the whole MEA molecule taking ...
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Why does the degree of dissociation change when we dilute a weak acid even though the equilibrium constant $K$ is constant?

$K$ represents the ratio of concentrations of molecules in a solution at equilibrium, which means that $Q_\mathrm{r}$ (that ratio at any given point) looks to be identical to $K$. In other words, the ...
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Calculating Equilibrium Partial Pressures Given Kp and Mass

For the reaction $$\ce{AsCl5(g) <=> AsCl3(g) + Cl2(g)}$$ at $550$ K, the equilibrium constant ($K_p$) is $9.81$. Suppose that $3.150 \ g$ $\ce{AsCl5}$ is placed in an evacuated $600$ ml ...
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How can you use ICE tables to solve multiple coupled equilibria?

If I have a problem involving multiple coupled equilibrium reactions, such as Calcium fluoride, $\ce{CaF2}$, has a molar solubility of $\pu{2.1e−4 mol L−1}$ at pH = 7.00. By what factor does its ...
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361 views

Equilibrium constant for complex cobalt ion

What is the equilibrium constant for the $\ce{Co(H2O)_6^{2+}(aq) + 4 Cl-(aq) <=> CoCl_4^{2-}(aq) + 6H2O(l)}$? I've looked at various sources but none seem to yield the actual equilibrium ...
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1answer
293 views

Determining the reduction potential of a half cell reaction at a given pH

$E^\circ_\ce{Cu^2+|Cu} = \pu{0.34 V}$. What will be reduction potential at $\mathrm{pH} = 14$ for the same couple? Given that $K_\mathrm{sp}$ of $\ce{Cu(OH)2}$ is $10^{-19}$. My Attempt I think ...
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1answer
128 views

Decrease of volume by half in equilibrium - with specific numbers- how to solve?

$$\ce{CO (g) + Cl2(g)<=>COCl2}(g)$$ We have 2 mols of $\ce{CO}$, 1 Mol of $\ce{Cl2}$,and 9.765 Mols of $\ce{COCl2}$ contained in 1 L. The system is currently in equilibrium. We ...
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639 views

Is liquid water in equilibrium with water vapor at room temperature?

This question was inspired by Why does liquid water form when we exhale on a mirror?. This question is different from Why does water evaporate at room temperature? because it asks about whether an ...
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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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126 views

Why can't a weaker acid protonate the conjugate base of a stronger acid?

So I've heard that, supposedly, a weaker acid cannot protonate the conjugate base of a stronger acid to give that stronger acid. For instance, adding ethanoic acid to sodium sulphate will not result ...
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210 views

Is common ion effect applicable on two strong electrolytes

Consider the nitration of benzene using mixed conc. $\ce{H2SO4}$ and $\ce{HNO3}$.If a large amount of $\ce{KHSO4}$ is added to the mixture the rate of nitration will be : Faster Slower Unchanged ...
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349 views

Determination of pKb of a mono acidic base

$20$ mL of a weak monoacidic base($\text{BOH}$) requires $12$ mL of $0.3$ M $\text{HCl}$ solution for the equivalence point. During titration, the pH of the base solution was $10$ upon the addition of ...
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276 views

Can we combine two reactions and then calculate the equilibrium concentrations?

At a certain temperature, $\ce{N2O5}$ dissociates as: \begin{align} \ce{N2O5 (g) &<=> N2O3 (g) + O2 (g)} & K_1 &= 4.5 \end{align} At the same time, $\ce{N2O3}$ also dissociates ...
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867 views

Calculate pH of a buffer solution

Calculate the pH in a buffer prepared from $\pu{50 mL, 0.30 M}$ formic acid ($\ce{HCOOH}$) and $\pu{30 mL, 0.40 M}$ sodium formate ($\ce{HCOONa}$). My way of solving: $n_{\ce{HCOOH}} = 0.05 \times ...
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Q. 36 2018 molar solubility of CaF2 at pH3 given molar solubility at pH7 and pKa of HF [closed]

This is Q36 on the 2018 Chemistry Olympiad: Calcium fluoride, $\ce{CaF2}$, has a molar solubility of $\pu{2.1e–4 mol L–1}$ at pH = 7.00. By what factor does its molar solubility increase in a ...
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How can the ocean act as a buffer?

I was reading up on the buffering effect of the ocean and I was quite confused about how the buffer is able to do anything. The buffer I will refer to is below: $$\ce{CO3^{-2} +H2O <=> HCO3 + OH^...
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Why proton concentration is divided by 10⁻⁷?

I am reviewing the book Biochemistry Concepts and Connections by Appling, Cahill, and Mathews and I cannot understand why they divide by the hydrogen concentration by $10^{-7}$. Why not just leave it ...
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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 ...
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What does the reaction of hydrogen and iodine to hydrogen iodide look like?

The reaction, $\ce{H2 + I2 <=> HI}$ is often used as an example for equilibrium reactions. It is however a difficult reaction to show in a school laboratory: we are not equipped to work with ...
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Error with explaination of shape of weak acid strong base titration?

I have read the other posts on the same question posted on chemistry exchange such as this one: Shape of Weak-Strong Acid-Base Titration and here : What does the small, steep curve at the very ...
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1answer
161 views

Determining reaction order in equilibrium reactions [closed]

Am hoping that someone can help me with the below question, and that I am asking in the right place. Am new here, so please forgive any missteps. Given a reaction like this: $$\ce{A + B <=> C +...
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Distribution coeffecient without concentrations

From what I understand about distribution coefficient is straight from my book — which does not give any practice examples — is that $$D = \frac{C_\mathrm{A}(\text{ext})}{C_\mathrm{A}(\text{orig})}$$ ...
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Using Le Chatelier's Principle [duplicate]

The following reaction is allowed to reach equilibrium. $$\text{CoBr}_2(g)\rightleftarrows\text{CO}(g)+\text{Br}_2(g)$$ What happens to the reaction when inert argon gas, $\text{Ar}(g)$, is added? ...
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Pressure at which graphite and diamond are in equilibrium

I came across this problem : The standard state Gibbs free energies of formation of C(graphite) and C(diamond) at $T = \pu{298 K}$ are $\pu{0 kJ mol-1}$ and $\pu{2.9 kJ mol-1}$, respectively. The ...
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1answer
1k views

Equilibrium constant for the neutralization of weak acid by strong base

Acetic acid has a $K_\mathrm{a}$ of $\pu{1.8e-5}$. What is the equilibrium constant for the neutralization of this acid with $\ce{NaOH}$? Given acetic acid $$\ce{HC2H3O2 + H2O <=> C2H3O2- + ...
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1answer
827 views

Effect of temperature on equilibrium constant in terms of entropy change

This question was asked in the JEE examination of 2017 : [A] option is incorrect since the system is losing heat and hence $$ \Delta S = -ve$$ [B] Lets assume we have an endothermic reaction $$\...
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1answer
54 views

Equilibrium - Pressure Vs. Concentration [closed]

Does increasing the pressure increase the concentration of reactants as well? If: $$\ce{A(g) + B(g)<=>C(g) + D(g)}$$ Assuming all reactants and products are gases. According to Le Chatelier'...
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106 views

How is preparing a buffer possible?

I understand the concept of an equilibrium buffer solution, however I am a bit hung on how creating it doesn't shift the weak acid equilibrium. $$\ce{CH3COOH + H2O <=> CH3COO- + H3O+}$$ $$ K_\...
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950 views

Calculating solubility of iron(III) hydroxide in water

The following example in Skoog's Analytical Chemistry uses mass-balance and charge-balance equations to calculate the solubility of iron(III) hydroxide in aqueous solution. $$ \begin{align} \ce{Fe(...
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175 views

Does ammonium react with water in an ammonia solution?

In the following equilibrium: $$\ce{NH3 + H2O <=> NH4+ + OH-}$$ Is it possible for the ammonium to simultaneously establish another reaction with water? $$\ce{NH4+ + H2O <=> NH3 + H3O+}$...
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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 ...

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