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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0answers
45 views

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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137 views

What happens when chemical equilibrium is restored after being disturbed?

I'm aware that, according to Le Chatelier's principle, a reaction will shift its equilibrium position in order to counteract the disturbance at equilibrium. However, I don't know what that means after ...
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182 views

Molarity and equilibrium reactions Kc [closed]

Samples of $\ce{A}$ ($\pu{1.40 mol}$) and $\ce{B}$ ($\pu{0.80 mol}$) are placed in a $\pu{2.0 L}$ container and the following reaction takes place: $$\ce{2 A (g) + B (g) <=> C (g) + D (g)}$$ At ...
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472 views

pH of 0.05 M NaH2PO3

What is the pH of a $\pu{0.050 M}$ solution of $\ce{NaH2PO3}$? I am given that $\mathrm{p}K_\mathrm{a1} = 2.0$ and $\mathrm{p}K_\mathrm{a2} = 6.58$. I am getting two different answers, $3.94$ and $4....
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1answer
555 views

H2O and Le Châtelier’s principle [duplicate]

According to Le Châtelier’s principle, the adding of a reactant causes a shift in the direction of products, to minimize the modification. But what about $\ce{H2O}$? When can it be considered as a ...
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1answer
66 views

Acidity of carbonate ions creates paradox?

Whilst I understand why salts can be acidic or basic, the carbonate reaction confuses me (carbonate being a basic ion). $$\mathrm{{CO_3}^{2-} + H_2O \ce{<=>} {HCO_3}^- + OH^-} \\ \mathrm{{...
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1answer
65 views

Why doesn't chemical equilibrium lead to uncertainties?

Let's consider a reaction $$\ce{a A + b B <=> c C + d D}$$ We will also assume that the concentrations are low and the activity coefficient is one. Now let's say initially one has $p_0$, $q_0$,...
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1answer
120 views

What would be different about a heavy-water ocean world?

The water on Earth is primarily made of $\ce{H2O}$. I'm wondering about the conditions in a hypothetical $\ce{D2O}$ ocean world. Would it be stable over geologic timescales (~$\pu{0.1–2 Ga}$)? What ...
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114 views

Which rate, the forward or reverse rate of acid dissociation, is more strongly affected when diluting acetic acid in aqueous solution?

Acetic acid is a weak acid. It is in equilibrium with acetate and hydronium ions in aqueous solution: $$\ce{CH3COOH(aq) + H2O(l) <=> CH3COO-(aq) + H3O+(aq)}$$ Ostwald's law states that the ...
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1answer
195 views

Why degree of dissociation/ionisation affected by dilution? [closed]

What happens when we dilute, say, an acid which is weak, and then add water to it? What motivates or pushes it to dissociate more? We are just adding some molecules of water, right? So, what exactly ...
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1answer
85 views

How to calculate the standard Gibbs energy at equilibrium?

Given that $K_c = 1.7 \times 10^{-13}$, calculate $\Delta G^{\circ}$ for this equilibrium mixture at $\pu{298 K}$. $$\ce{N2O (g) + \frac{1}{2}O2 (g) <=> 2 NO (g)}$$ I've calculated: $$ \begin{...
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1answer
417 views

Whats the difference between reversible process in thermodynamics and reversible chemical reactions?

We know that in thermodynamics, reversible process never occur since entropy should be conserved. However, in chemistry we do have a lot of reversed chemical reactions that forms reactants from ...
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2answers
49 views

Can equilibrium be calculated at any time of an acid base reaction and still be the same? [closed]

Should the equilibrium constant $K$ be calculated at the end of an acid-base titration or can we calculate it in the middle of the titration for example? If so, will the calculated equilibrium ...
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Calculating the amount of a product at the reaction equilibrium

$\ce{Cr2O3}$ can be reduced to the elements chromium with high temperature and carbon by this two reactions: $$ \begin{align} \ce{Cr2O3(s) + 3C(s) &-> 2Cr(s) + 3 CO(g)} \label{rxn:1}\tag{1}\\ \...
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Determining the equilibrium constant

This is freely translated, I hope it's not too bad. The reaction to dehydrate methylcyclohexane to toluene in the gaseous phase: Formulate the reaction equilibrium's constant. Now, that's not a ...
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1answer
635 views

Gibbs free energy ΔG=ΔG°+RTln(Kp) different expressions for ΔG

ΔG=ΔG°+RTln(Kp) If I understand it correctly, the ΔG in this equation gives the "distance" in Gibbs free energy of a chemical system at a particular moment in a reaction (encoded by the Kp) to the ...
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1answer
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Balancing an equation

so I might be just way to tired for this, but I somehow have a stupid mistake here when trying to balance an equation. $$Zn(s)+MnO_2(s)+NH_4^{+}(aq)=Zn^{2+}(q)+Mn_2O_3(s)+NH_3(aq)+H_2O(l)\tag{1}$$ ...
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1answer
630 views

Can an iodine clock reaction work without using a strong acid?

I'm going to do an iodine clock reaction for a project and we had to submit the materials and safety sheets for the experiment a while ago. I thought I could do one by using hydrogen peroxide, sodium ...
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1answer
931 views

What is exactly meant by position of equilibrium? [duplicate]

I'm confused with the terms "position of equilibrium" and "equilibrium shifting towards left/right". I do have a vague picture that if a reaction shifts to the right, for example, it basically means ...
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Determining mole fraction of carbon dioxide knowing Kp only

I've been assigned the following problem at school: Given the following reaction: $$\ce{C (s) + CO2 (g) <=> 2 CO (g)}$$ Find the mole fraction of $\ce{CO2}$ provided that, in equilibrium, $K_\...
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536 views

Calculating dissociation degree from pH and Ka without given initial acid concentration

Is it possible to calculate the dissociation degree (DD) from pH and Ka without directly been given the initial acid concentration? I found the following formula: $$\text{DD} = \frac{K_\mathrm{a}}{...
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2answers
255 views

Why are reversible reactions spontaneous?

If a reversible chemical reaction is spontaneous in one direction, shouldn't it be non spontaneous $(ΔG > 0)$ in the other? In other words for the reaction: $$\ce{A + B ⇌ C + D}$$ if $$\ce{A + B ...
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4answers
633 views

Changes in pressure for an equilibrium reaction containing a solid/liquid on one side only

For a reaction where there is only one solid/liquid present, but gases present as both reactants and products (are there any examples of this type of reaction?): $$\ce{A(s) + B(g) <=> C(g)},$$ ...
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3answers
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What are the units of Kc and Kp?

They are both equilibrium constants as far as I know. Kc is in terms of molarity and Kp is in terms of pressure. Also both of them are ratios of respective quantities [ ratio of molarity(s) in Kc and ...
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1answer
138 views

Why does ligand substitution occur when OH- is a better ligand than NH3?

$$\ce{[Cr(H2O)3(OH)3](s) + 6NH3 -> [Cr(NH3)6]^3+ + 3H2O + 3OH-}$$ When excess $\ce{NH3}$ is added to triaquatrihydroxychromium(III), why does ligand substitution occur when $\ce{OH-}$ is a better ...
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1answer
268 views

Equilibrium constant from mole ratio

Chapter 4, problem 13 from the Chemical Priciples [1, p. 170]: Equilibrium concentrations Experiments have shown that at $\pu{60 °C}$ and $\pu{1 atm}$ total pressure, the equilibrium ratio of $\ce{...
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49 views

Equilibrium :. Why does a system at equilibrium try to undo the effect of external stress applied on it? [duplicate]

" Le Chatelier principle states that a system at equilibrium when subjected to external stress tries to undo the effect of that stress" In short, why does system at equilibrium follow Le Chatelier ...
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1answer
135 views

Water vapour pressure in oxygen gas bubble

Suppose we have a source of O$_2$ bubble formation in water at specific nucleation sites, how can we estimate the water vapour pressure inside the O$_2$ bubbles? I know that: (1): $p_\mathrm{O_2}+...
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1answer
285 views

Doesn't Ostwald's law of dilution contradict Le Chatelier's principle?

By Le Chatelier's principle, increasing the concentration of a weak electrolyte brings out more ions. By Ostwald's dilution law, increasing the concentration of a weak electrolyte brings out less ...
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1answer
262 views

What's the difference between “extent of reaction” and “position of equilibrium”?

My chemistry textbook defines the terms in question as follows: Extent of reaction: the relative amounts of products compared with reactants. The extent of reaction is indicated by the value of the ...
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311 views

How to find equilibrium constant in reactions which have a limiting reagent?

If in the following reaction $$\ce{H2 + I2 <=> 2HI}$$ the initial concentrations of $\ce{H2}$ and $\ce{I2}$ are $\pu{1 M}$ and $\pu{5 M}$, respectively, and at equilibrium $x$ moles of ...
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pKa Conceptual Questions [closed]

If anyone could clear up some of this conceptual confusion, that would be much appreciated. Is $\mathrm pK_\mathrm a$ an intrinsic property of a molecule? Or extrinsic? A property is extrinsic if it ...
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2answers
86 views

Does concentration or pKa define acid strength?

For example, is 3M HCl a stronger acid than 1M HCl? I would reason that the concentration of an acid/base does not influence its strength. Strength is determined by the pKa, and, as per Le Chatelier'...
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1answer
33 views

Effect of increasing product concentration on time of completion of reaction

This was the question asked in our chemistry exam: In the experiment of determination of equilibrium constant of esterification of ethanol, if , instead of using clean dry bottle, if a bottle already ...
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1answer
54 views

Why does a Lower Concentration of SO2 call for an increase of equipment dimensions in a Contact Process Plant?

I'm working on a presentation based on an article about the Contact Process (production of sulfuric acid), and it says that using a low concentration of SO2 at the entrance of the converter (in which ...
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221 views

Manganese (II) oxidation by air

I am studying the reaction of dissolved dioxygen with manganese(II) hydroxide for the Winkler method: 2Mn(OH)2(s)+O2(aq)⟶2MnO2(s)+2H2O(l) The ...
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1answer
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Polyprotic acid - How does one calculate the CONCENTRATIONS of ALL species present in a solution when you start with 0.3M NaH2PO4? [duplicate]

Can anyone give me a push in the right direction, how do I calculate the concentration of all species present in a solution with 0.3M NaH2PO4. So the concentration of H3PO4, H2PO4 -, HPO4 2-, PO4 3- ...
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3k views

How to derive the relation between gibbs energy and equilibrium constant?

I want to understand the derivation between gibbs energy and equillibrium constant $$\Delta G=\Delta G^o+RT\ln Q?$$ I have seen a similar post on CSE Derivation of relationship between equilibrium ...
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2answers
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Chemical Equilibrium in case of copper(II) ions [closed]

$\pu{Cu^{2+}}$ ions react with $\pu{Fe^{2+}}$ ions according to the following reaction: $$\ce{Cu^+2 + 2Fe^2+ <=> Cu + 2Fe^3+}$$ At equilibrium, the concentration of $\pu{Cu^{2+}}$ ions is ...
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1answer
166 views

chemical equilibrium and exothermic reaction

here is an interesting question about the chemical equilibrium and Le Chatelier's principle. the following pressure show the partial that produced in the equilibrium reaction at time (t1 and t2) $$\...
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In a saturated solution, why is there ongoing dissolution and crystallisation?

I was studying equilibrium, and had this question.. In a saturated solution with sugar dissolved, why is there a constant process of dissolving and crystallising? What I mean by this is, why don't ...
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1answer
2k views

What is the pH of a solution made by mixing 10.00 mL of 0.10 M acetic acid with 10.00 mL of 0.10 M KOH?

What is the pH of a solution made by mixing 10.00 mL of 0.10 M acetic acid with 10.00 mL of 0.10 M KOH? The $K_a =1.8 × 10^{-5}$ for $\ce{CH_3CO_2H}$. Assume that the volumes of the solutions are ...
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1answer
201 views

Equation for the equilibrium constant for the hydration of carbonyls using UV spectroscopy

I was looking through the literature when I found a paper by Greenzaid et al. [1] which states that the equilibrium constant $K_\mathrm{hyd}$ is: $$K_\mathrm{hyd} = [\text{hydrate}]/[\text{carbonyl}] ...
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3answers
3k views

molar solubility of CaF2 at pH3 given molar solubility at pH7 and pKa of HF

Here was my attempt #$1$ at a solution. $K_{sp}=[Ca^{2+}][F^-]^2$ Using the information at pH=7, I estimated that $K_{sp}\approx3.7\cdot10^{-11}$, which means that barely any HF formed. I assumed ...
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427 views

How can I find the equilibrium constant Kp without temperature?

The question I'm looking at is I found that that Kc = 139M^-1, but how can I determine Kp? There is no temperature given, but I was told that it is still possible to calculate.
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1answer
814 views

Calculating molar solubility of calcium hydroxide from solubility product

On the Wikipedia page for calcium hydroxide, the stated solubility product for $\ce{Ca(OH)2}$ is $K_\text{sp} = \pu{5.5 * 10^{-6} M^3}$. It doesn't stipulate the temperature, but I have a chemistry ...
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1answer
56 views

Solving chemical equilibrium equation by hand [closed]

I was trying to solve question 22 above. I obtained the equation: $$50=\dfrac{4\alpha^2}{(1-\alpha)(2-\alpha)}$$ Now, the resulting quadratic is too much of a pain to solve. How would one use ...
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2answers
63 views

Is iron(III)nitrate changed and if so how?

We have the solution: $\ce{Fe^3+(aq) + SCN-(aq) <=>Fe(SCN)^2+}$ When we add more $\ce {SCN-}$ to the solution above, the solution produces more product. My question is, how does it affect $\...
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1answer
523 views

Why does a catalyst increase the forward and reverse reactions equally

With reference to the picture below, how is it that when there is a lower activation energy (due to the alternate reaction pathway provided by the catalyst) that the catalyst will increase the forward ...
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1answer
932 views

Why are solids and liquids ignored in the equilibrium constant?

If a reaction is taking place and is going towards equilibrium, wouldn’t the reactant be consumed to form products and vice versa? If this reactant/product is a solid or liquid, wouldn’t the number of ...

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