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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52 views

Is there any proof of law of mass action? [duplicate]

I was studying chemical equilibrium and my teacher taught me the law of mass action given by Guldberg and Waage. But is there any proof of this law? I did not find the proof anywhere. I searched all ...
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Why do diplumbenes (Pb=Pb double bonded compounds) break apart in hydrocarbon solution?

In group 14, the double bond becomes increasingly weaker down the group. Our lecturer told us that many distannenes ($\ce{>Sn=Sn<}$) and almost all diplumbenes ($\ce{>Pb=Pb<}$) dissociate ...
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Confusion regarding the mechanism of acidic/basic buffer solutions

While learning about acidic and basic buffer solutions we were told that they can resist pH change if we add small amounts of acid or base by neutralizing the $\ce{H+}$/$\ce{OH-}$ ions from the added ...
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What is the difference between these equations for the Contact process?

Some webpages describe the contact process as this (I left out $\ce{SO2}$, $\ce{SO3}$ production): $\ce{SO3 + H2SO4 -> H2S2O7}$ After this, it is controllable to add water to the oleum therefore ...
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Is ionisation an equilibrium process?

I read in a page that ionisation is an irreversible process. But, as equilibrium is always reversible would that mean equilibrium does not involve ionisation process. And than dissociation is a ...
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Why is the triple phase diagram of water different from the general substances?

The fusion curve of triple phase diagram of water and fusion curve of triple phase diagram of general substances is different. Why is it so?
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Which factors determine the keto:enol ratio for aldehydes, ketones, and 1,3-dicarbonyl compounds?

Arrange the following compounds in order of increasing enol content: I think the order is D > C > B > A considering conjugation, hyperconjugation and hydrogen bonding. The enol formed in ...
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Molecular Docking physiological effects

If I wanted to perform a Virtual Screening for one molecule and several ligands, take for example, the docking between TDO protein and several antidepressant drugs: How would I be able to correlate ...
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Auto-ionisation and Dilution

When you dilute an acidic solution, pH increases towards 7 and pOH decreases. However, the decrease of pOH indicates that the concentration of hydroxide ions increases. This seems to contradict my ...
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Why is the equilibrium constant increasing in this exothermic reaction?

A problem asks, if you have a positive $\Delta S$ (positive change in entropy) for an exothermic (meaning a negative $\Delta H$, or negative change in enthalpy) reaction and temperature increased, ...
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Why are solids and liquids not included in the equilibrium constant? What about in a reaction rate calculation?

Take for instance the reaction $$\ce{H2(g) + I2(s) <=> 2HI(g)}$$ The equilibrium constant would not include the solid $\ce{I2}$, but why is this? I have read that its concentration is a ...
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Triple Point of a compound and critical point

Is it necessary for all compounds to have a triple point? Also, how is the triple point determined? Suppose a substance does not have a triple point, so how do researchers agree on the impossibility ...
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Sequential reaction in equilibrium

Derive an equation for the steady-state rate of the sequence of reactions $$\ce{A <=> B <=> C <=> D}$$ with $[\ce{A}]$ maintained at a fixed value and the product $\ce{D}$ removed as ...
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Equivalence point pH derivation of a tribasic acid

Considering $\pu{100 mL} \ \pu{0.1 M} \ \ce{H3A}$ and $\pu{0.1 M} \ \ce{NaOH}$ titration curve: I understood the half equivalence points, but couldn't understand the reason why $\mathrm{pH} = \frac{1}...
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Equilibrium of zinc ion with ammonia

In my chemistry lab, we are testing the amphoteric properties of this metal. I understand zink can react with an acid or a base to form different compounds in solution based on pH. In one part of the ...
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Equilibrium: Effect of change in composition and value of Kp, Kc on changing pressure

Di-hydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction: $CH_4{_{(g)}}+H_2O_{(g)} \ce{<=>} CO_{(g)}+3H_2{_{(g)}}$ How will ...
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Finding a Mistake Calculating the pH of Ammonium Acetate

I'm trying to calculate the $\mathrm{pH}$ of a $\pu{0.10 M}$ solution of ammonium acetate, and I am struggling to find what mistake I am making within the following calculations: We know that $\dfrac{[...
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Changing pressure on equilibrium

Recently I heard my teacher say that when increasing the total pressure of the system, the reaction which is "more dependent on collisions" is favoured. This seems to make sense, although I'...
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Calculating the pH of a 'buffer' solution?

Question: Determine the $\mathrm{pH}$ of the solution resulting when $\pu{100 cm^3}$ of $\pu{0.50 mol dm-3}$ $\ce{CH2ClCOOH}$ is mixed with $\pu{200 cm^3}$ of $\pu{0.10 mol dm-3}$ $\ce{NaOH}$. The ...
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pH of ammonium acetate solution

I'm trying to calculate the pH of a 1M $\ce{NH_4CH_3COO}$. I know that I'll have these reactions: $\ce{NH_4CH_3COO <=> NH_4^+ + CH_3COO^-}$ $\ce{NH_4^+ <=> NH_3 + H^+}$ $\ce{CH_3COOH <=...
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Symbolic form of equilibrium constant for ammonium carbamate dissociation

$$\ce{NH2COONH4(s) <=> 2 NH3(g) + CO2(g)} \qquad K = \left(\frac{p(\ce{NH3})}{p^\circ}\right)^2\times\frac{p(\ce{CO2})}{p^\circ}$$ Assuming that you start this experiment with pure solid $\ce{...
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Can the degree of dissociation of a weak acid be more than 1?

My common sense dictates that it can't be more than 1 because after all it is the number of moles dissociating per mole of a substance. But I was reading about Ostwald's law of dilution and came ...
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1answer
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Doesn't adding an inert gas at constant volume increase the partial pressures?

When you add an inert gas to a container of constant volume full of gases, you are basically shoving the inert gas into the container and increasing the pressure inside the container, so the partial ...
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Physical Chemistry: Specifically the Dissolution of Carbonates

Please note this question is different to the other that keeps being mentioned. That one is about the concentration of just $\ce{HCO3-}$ when no $\ce {pH}$ was given. Whereas, in this one I am trying ...
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Gibbs Free Energy and Equilibrium [closed]

In a problem, it was stated that at 25 degrees Celsius, the K(eq)<1. The question than asked whether T(Δ(S)) was larger than, smaller than, or equal to ΔH for this reaction and the equation ΔG = ΔH ...
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What happened to the Na+ ion? [closed]

I was in the middle of my acid and base schools questions when I came to a stop at this question. I have posted the answer to tell you what I am confused about. My teacher did not explain this very ...
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1answer
126 views

How to calculate molar concentration from equilibrium equations with no initial concentration given?

I have the equations: \begin{align} \ce{CO2(g) + H2O(l) &<=> H2CO3(aq)} &\quad K_1 &= 10^{-1.47} \tag{1}\\ \ce{H2CO3(aq) &<=> H+(aq) + HCO3-(aq)} &\quad K_2 &= 10^{-...
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How to calculate molar concentration from equilibrium equations with no initial concentration given [duplicate]

Consider the following equations: \begin{align} \tag{1} \ce{CO2 (g) + H2O (l) &<=> H2CO3 (aq)} & K_\ce{CO2} &= 10^{-1.47}\\ \tag{2} \ce{H2CO3 (aq) &<=> H+ (aq) + HCO^...
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258 views

How does addition of AgCl affect concentration of iodide in KI solution?

In a mixture of $\ce{AgCl(s)}$ and initial $\pu{0.10 M}$ $\ce{KI}$, what is the $[\ce{I-}]$ after the reaction proceeds? Disclaimer: This is not a graded assignment, but rather a problem I'm trying to ...
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Why is the Ag+ concentration in a beaker fixed in the reaction between excess AgCl (s) and KI (aq) from the start? [duplicate]

This arises as a sub-question for the following question: Calculate the concentration of I- in a solution obtained by mixing 0.10 M KI with an excess of AgCl(s). I tried to look at How does addition ...
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Why is Ag+ not hydrolysed?

Usually, strong acid anions and strong base cations don't get hydrolysed. But I've noticed through some questions that $\ce{Ag^+}$ doesn't seem to get hydrolysed, why is that? Is there any concept ...
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113 views

How to know if a reaction forms H3O+ ions or OH- ions? [closed]

How would you know when an acid or base is paired with $\ce{H2O}$ that it will form an $\ce{OH-}$ ion or a $\ce{H3O+}$ ion? I just started the acid and base equilibrium unit, and I'm just confused on ...
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Neutralisation of weak acid by base

I'm still working on my concepts related to chemical equilibrium. I came across this question: 10mL of a weak acid HA is 20% dissociated in water. This solution is completely neutralised by 10 mL of $...
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Can potassium carbonate be used to calibrate hygrometers?

Context: In the process of trying to calibrate a number of hygrometers, with Sensirion MEMS electronic sensors, I came across the method of using wet salt: an airtight container will stabilize at a ...
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Adding aluminum sulfate to neutralize an aqueous solution of sodium silicate with pH of 12.6

How much aluminum sulfate do I need to add to an aqueous solution of sodium silicate to neutralize the solution (pH from 12.6 to 7)? For a water treatment school project, we remove sodium silicate ...
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Given an unbalanced chemical equation, is it possible to determine the largest possible coefficient that could be used in the balanced equation?

I am writing a program to balance chemical equations, and would love to know if there is an algebraic way to determine the greatest possible coefficient that I would need to check.
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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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858 views

Which make HCO3- to show two pH values at two scenarios?

According to the below two titrations, Image Reference If we consider the reactions, at the first reaction (in first figure after adding 1.0), there is $\ce{HCO3-, NaCl,}$ and $\ce{H2O}$ at the first ...
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Why does this acid-base reaction occur?

My teacher told me about the reaction of sodium peroxide with water: $$\text{Na}_2\text{O}_2 + 2\text{H}_2\text{O} \ce{->} \text{H}_2\text{O}_2 + 2\text{NaOH}$$ Now, the concentration of products ...
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Decomposition of Hydrogen Peroxide Catalysed by Potassium Iodide in Basic Solution

As part of my high school project, I had to measure the initial rate of decomposition of hydrogen peroxide catalysed by potassium iodide at different pHs. At higher pHs (alkaline conditions), I found ...
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Understanding Pourbaix diagram

I am recently taking courses in environmental chemistry and I was introduced to Pourbaix diagram. I was taught that the lines in the Pourbaix diagrams are equilibrium lines. Lets take as an example ...
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503 views

Preparation of a HCN/NaCN buffer that has a pH of 9.8 and an osmotic pressure of 1.35 atm at 298 K

You are asked to prepare $\pu{2.0 L}$ of a $\ce{HCN/NaCN}$ buffer that has a $\mathrm{pH}$ of $9.8$ and an osmotic pressure of $\pu{1.35 atm}$ at $\pu{298 K}$. What masses of $\ce{HCN}$ and $\ce{NaCN}$...
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Reaction stoichiometry for calculation of Kp

NH$_2$CO$_2$NH$_4$(s)⇌$2$ NH$_3$(g)+ CO$_2$(g) I want to calculate K$_p$ for the reaction above, given that the total pressure is $0.63$ bar. My calculations: $0.63$ = p(CO$_2$) + p(NH$_3$) , where ...
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On the activity of liquids and solvents in equilibium constants

This is a confusion I've had for quite sometimes, first when learning about equilibria (due to contradicting teachers), then when trying to teach it (due to contradicting sources, in books and on the ...
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What does isohydric solution mean?

While studying ionic equilibrium, I came across the term "Isohydric Solutions" which is defined as: Solutions of electrolyte are said to be isohydric if the concentration of the common ion ...
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What is the difference between atom and nucleus? [closed]

Atomic nucleus-The atomic nucleus is the small dense region consisting of protons and neutrons at the center of an atom discovered in 1911 by EARNEST RUTHERFORD. Atoms are made up of a positively ...
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Why are shells softening in the ocean?

I learnt about how ocean acidification can be described in terms of equilibrium. This is summarized in the textbook diagram below: However, this diagram doesn't explain to me why the shells should be ...
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1answer
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Disparity between LeChatelier's Principle and Solutions

Let's say that there is a solution $\ce{Na+(aq) + Cl-(aq) <=> NaCl(s)}$ If the above solution is at equilibrium we can say that it is saturated and hence no more Sodium Chloride will dissolve. ...
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Why does the pH of the endpoint decrease when temperature of the titration is increased? [duplicate]

I was doing an experiment in chemistry class involving titrations. I would heat up different samples of vinegar and titrate them using NaOH. The trend that I found was how has temperature increase, ...
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Question regarding chemical equilibrium when adding a salt to acid solution

Having read the following was wondering something: $$\mathrm {p}K_\mathrm{a} = -\log\frac{[\ce{H+}]_\mathrm{eq}[\ce{A-}]_\mathrm{eq}}{[\ce{HA}]_\mathrm{eq}} $$ $$\ce{HA <=> H+ + A-}$$ $$\mathrm{...

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