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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Why does the equation for chemical potential apply to liquids and aqueous solutes?

The equation for chemical potential of a gas can be derived as such: At constant temperature, $$\mathrm dG = V\,\mathrm dP \label{eqn:1}\tag{1}$$ Substituting with the ideal gas law $PV = nRT$, $$\...
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thermodynamic equilibrium

A thermodymic system is said to be in equilibrium if it satisfies the two conditions : 1-The system’s macroscopic properties remain constant with time. 2-removal of the system from contact with its ...
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Mathematical models of Vaporization-Condensation dynamics

I am a mathematician now studying an introductory chemistry course. Consider a liquid in a closed container, at (say) room temperature. Then some of the liquid will vaporize. Then some of the ...
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Why is this equation true for a salt in acid?

I previously asked a question about a calculation (below) Calculate the molar solubility of $\ce{SrF2}$ in a solution buffered at pH = 2.00. ($K_{a}$ for HF is $7.2 \times 10^{-4}$). The $K_{sp}$ of $...
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Reason of using reversible signs [duplicate]

We see that for weak electrolytes we use $$\ce{<=>}$$ e.g reversible symbol and for strong ones we use $$\ce{->}$$ e.g irreversible symbol. For example,we write $$\ce{CH3COOH <=> CH3COO^...
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"The neutralization reaction between a weak acid and a weak base never occurs to the right of the equilibrium" - what does my book mean?

[Book: Chemistry-2nd Paper (Class XI-XII) January 2020 by Hajari & Nag, Bangla version, p-410] I don't think my book is using the terms "right" and "equilibrium" correctly. If ...
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Is there an agreement for a specific temperature referred to in the context of standard Gibbs energy? [duplicate]

I found an exercise in Physical Chemistry by Atkins et al, 8th edition, page 235 that I found confusing. The question is as follows. "7.2(b) Molecular bromine is 24 per cent dissociated at 1600 K ...
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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 don't we multiply Ksp and Kf?

My understanding is that for a process with two reactions having the equilibrium constants K1 and K2, K for the full process is K = K1 x K2. However, in this problem in my book where complexation ...
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Electrode potential for saturated silver carbonate solution

An electrochemical cell is set up to measure the electrode potential $E(\ce{Ag^+}/\ce{Ag})$ using the saturated $\ce{Ag2CO3(aq)}$ solution $(K_\mathrm{sp}(\ce{Ag2CO3(aq)},\pu{25 °C}) = \pu{6.3E-12})$ ...
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Finding relation between Gibb's free energy and equilibrium constant for a homogeneous gaseous phase reaction

I was trying to find relation between Gibb's free energy change and equilibrium constant for the following homogeneous gaseous phase reaction at constant temperature $$\ce{aA +bB }\rightleftharpoons \...
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H+ concentration decreasing over time reasoning in weak acid strong base titration

We know that, when $\ce{CH3COOH}$ is just present in water, it is in equilibirum with water and having some $\ce{H+}$ dissociated to give some $\mathrm{pH}$ to it. Now when we start adding $\ce{NaOH}$ ...
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Misconception regarding mean ionic activity coefficient and applying it to equilibrium constants

I probably have some simple misconception about the mean ionic activity. The mean ionic activity coefficient is defined as $$ \gamma_{\pm} = \sqrt[^{p+q}]{\gamma^p_+\gamma^q_-} \tag{1} $$ I'm just not ...
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Importance of equilibrium constant [closed]

Here i am going to let out a doubt of mine which has been bothering me since high school about equilibrium constant. Let's say we have a reaction. $A+B\rightarrow C+D$. When we say reversible ...
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Vapor-Liquid Equilibrium and partial pressure of ammonia

I tried searching the forums for a similar question but I do not think it was entirely answered: Suppose I have a closed system in a container with solvent and a certain concentration of gas, say ...
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How to find ion concentrations at various points in a solution that will precipitate multiple insoluble salts?

The solubility product constant of lead (II) iodide is $1.2 \times 10^{-5}$ at 273 K. The solubility product constant for lead (II) carbonate is $1.5 \times 10^{-13}$ at the same temperature. 50 ...
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Interpreting Ternary Phase Diagram Stoichiometry

I am trying to locate the lowest-melting mixture in a system of three nitrate salts: sodium, potassium, and calcium nitrate. I have the relevant ternary phase diagram, but I am unsure exactly about ...
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Acidity and Basicity of titrate and titrant in Acid-Base titration

I want to know that do we always use monoprotic acid and bases in the Acid-Base Titration. And, if the answer is No. Then, I am confused in the definition of Equivalence Point, because I had seen on ...
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Combining two reactions in equilibrium with same reactants but different products: What would be the new K?

If I have the reactions : A(g) ⇌ B(g)   K1 A(g) ⇌ C(g)   K2 Am I able to add the equations like done in Hess's law despite nothing canceling out? And if I can do so, is the new equilibrium ...
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Relation between Solubility Product and Equilibrium Constant

I had read about Solubility, and I found that Solubility is not Molarity (because previously I believe that both are same thing). But, they have a big difference (source : https://en.wikipedia.org/...
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Why is molar density of solids and liquids taken as 1? [duplicate]

In the expression for equilibrium constant, the molar density values of solids and liquids are taken as 1. Is the active mass taken as the molar density of reaction divided by molar density at ...
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Standard Gibbs free energy when all the reactants and products are at standard condition

I have read in my textbook that for a reaction $\Delta G=\Delta G^o-RT\ln Q $, where $\Delta G^o$ is the Gibbs free energy change when the initial concentration of products and reactants are unity. ...
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Relevance of equilibrium constant Kp for reaction when reactant is solely a solid and is absent

Consider a reaction where a solid dissociates to give gases. There must a equilibrium between them, define the equilibrium constant in terms of pressure as $K_p$. Suppose I take the gases alone in a ...
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Can water synthesis and decomposition be in a dynamic equilibrium?

When heated at extreme temperatures, water can spontaneously decompose. According to Wikipedia (https://en.wikipedia.org/wiki/Water_splitting): In thermolysis, water molecules split into their atomic ...
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Between compounds having same functional groups, why does the one with greater -I effect have higher acidic strength

Consider the two compounds $\ce{FCH2COOH}$ and $\ce{ClCH2COOH}$. Since fluorine is more electronegative than $\ce{Cl}$ it will show a greater –I effect. It will pull the the electrons closer towards ...
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How does pH affect an extraction problem

I am not sure how to understand when pH will affect a given problem regarding extraction. For example, in a problem given that K$_D$ of the reaction is $1.86$ I am asked to calculate: (a) How much ...
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Chemical Equilibrium of the Esterification Reaction Between Propanol and Ethanoic Acid

I am trying to investigate the relationship between temperature and equilibrium constant of the esterification reaction between propanol and ethanoic acid in reflux system, with conc. sulphuric acid ...
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Calculate pH of imidazole in solution

I am having trouble understanding how to know how a molecule will reaction in solution. For example, if I have $\pu{1 M}$ of imidazole in solution, how can I calculate the pH of the solution by only ...
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What makes ammonia to dissociate when volume is increased?

What makes ammonia dissociate to $\ce{N2}$ and $\ce{H2}$ when the volume is increased (pressure is reduced)? I understand how pressure affects equilibrium. What happens after the $\ce{NH3}$ is being ...
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How can gradient of concentration-time graph be zero at equlibirum if the rate of reaction is non zero?

The rate of a reaction is usually measured as the rate of change of the concentration of a reactant or product with respect to time. Also, at equilibrium, the rates of the forwards and reverse ...
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Why is HONH2 basic?

I've been told that $\ce{HONH2}$ is a weak base because of its $K_b$ value of $\pu{1.1E-8}$. However, the $K_a$ value is larger ($K_a=K_w/K_b=9.9\times10^{-7}$), which I think would make it more ...
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Equilibrium in sodium bicarbonate and acetic acid reaction

I'm trying to understand how the equilibrium in the CH₃COOH + NaHCO₃ ⇌ NaCH₃COO + H₂CO₃ works. It seems that the better way to deal with this however was to change this to treat the HCO₃- ion as the ...
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Voltaic cell equilibrium confusion

In a voltaic cell, taking one with $\ce{Zn}$ and $\ce{Cu }$ electrodes for an example, an EMF is formed because the equilibria at the $\ce{Zn}$ electrode is shifted more towards the $\ce{Zn^2+ + 2e-}$ ...
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Chemical equilibrium textbook question

One textbook question that I came across is: How, the answer Doesn't make sense to me because when you add 3M of B, that's the initial position and not the equilibrium position. When you add 3 moles ...
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Finding dissolved amount of base from pH and solubility product

Calculate the amount of $\ce{Mg(OH)2}$ which is solubilized in $\pu{1.25 L}$ of a buffered solution at $\mathrm{pH} = 9.5$. $(K_\mathrm{sp}(\ce{Mg(OH)2}) = \pu{5.61E-12})$. From $\mathrm{pH}$ I ...
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Chemical equilibrium graph [closed]

How can we determine which reaction belongs to which graph. I mean in the above pic . We can observe two graphs and 2 equations. But there is no link between the two . Both the reactions proceed till ...
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How to calculate a citric acid and trisodium citrate buffer?

I am trying to calculate how to prepare 500 mL of a citric acid (H3Cit) and trisodium citrate (Na3Cit) buffer with a pH = 4.5 and a total concentration of 0.1 M. I know that it is necessary to use the ...
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Why does Raoult's Law have a weighted sum instead of a direct sum?

I'm fully aware of the various questions asked about Raoult's Law, and I'm asking this after having gone through all of them and not finding a suitable answer to my question. I have studied, that at a ...
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How to relate equilibrium constant and equilibrium conversion?

For the following gas phase reaction: $$ A\leftrightarrow B $$ The concentration equilibrium constant ($K_c$) can be expressed as: $$ K_c = \frac{c_B}{c_A} = \frac{\frac{F_B}{\vartheta}}{\frac{F_A}{\...
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An Index Poisoning Case Involving Dichlor and Carbonic Acid [closed]

I'm currently working an unusual case of poisoning, with Sodium Dichloro-S-Triazinetrione. In my case, I need to know the expected reaction with carbonic acid. I'm also curious if anyone could give ...
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How to estimate the pH of multi-component buffer (phosphate buffer in equilibrium with CO2 rich atmosphere)?

I wonder how the pH of buffer solution can be estimated if buffer consists of several systems in equilibrium to the gas phase. For example, (based on growth medium for one of the bacteria) buffer ...
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1 answer
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Do Kp and Kc depend on initial concentration of reactants?

Are $K_P$ and $K_C$ dependent on initial concentration of reactants? So far I had known that $K_P$ and $K_C$ are only dependent on temperature which is explained by thermydnamic approaches perhaps. I ...
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Graph of equilibrium constant vs 1/T

I have a problem with the 1st option, I did $\Delta G = -RTlog(Kp(RT)^{\Delta n})$ $\Delta H - T\Delta S = -RTlog(Kp(RT)^{\Delta n})$ $log(Kp) = \frac{\Delta S}{R} - \Delta nlog(RT) - \frac{\...
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Problem understanding the rate of reaction of reversible reactions

Case 1: $$\ce{CH_3COOH + NaOH<=>CH_3COONa + H_2O}$$ At equilibrium, there remain extremely small concentrations of the reactants (acetic acid and sodium hydroxide), and comparatively large ...
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Mass of silver iodide that dissolves in ammonia [closed]

What mass of $\ce{AgI}$ will dissolve in $\pu{1.0 L}$ of $\pu{1.0 M}$ $\ce{NH3}?$ Neglect the change in concentration of $\ce{NH3}.$ Given: $K_\mathrm{sp}(\ce{AgI}) = \pu{1.5E-16};$ $K_\mathrm{f}(\ce{[...
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2 votes
1 answer
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Why does the reaction of Brady's reagent and cyclohexanone not also form an enamine-type product?

In this reaction in a Khan academy video, cyclohexanone reacts with Brady's reagent to form hydrazone product. My question is why doea Brady's reagent + cyclohexanone not also form an enamine product ...
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How to find the temperature for when Kc = 1

The formulas I can use are $\Delta$G = H - T$\Delta$S, and $\Delta$G = $\Delta$G(s.t.d) + RTlnK I understand that when Kc is 1, the reaction is barely spontaneous and thus I can use the first formula ...
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What is the correct way to write dissociation reactions? [closed]

The variants are as follows: For a salt (NaCl): $$\ce{NaCl_{(s)}<=>NaCl_{(aq)}<=>Na_{(aq)}^{+} + Cl_{(aq)}^{-}}\tag{1}$$ $$\ce{NaCl_{(s)}<=>Na_{(aq)}^{+} + Cl_{(aq)}^{-}}\tag{2}$$ $$\...
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4 votes
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Why is the van ’t Hoff relation an approximation?

Lately, I've been looking and thinking about the fact that a professor told us in an advanced physiology lecture. When it came to mentioning osmotic pressure and the van ’t Hoff relationship $$ \pi = ...
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How high does the base dissociation constant, Kb, have to be for a base to be considered "strong"?

I'm just confused as to how high the Kb constant / how low the Ka constant needs to be for a base to be considered a "strong base." The conjugate base of hydrogen phosphate ion, phosphate ...
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