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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Determining change in dissociation constant due to common ion effect

Can the dissociation constant of hydrogen cyanide be decreased by by adding sodium cyanide? Does the equilibrium constant of $\ce{HCN}$ decrease due to common ion effect?
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In a binary liquid solution of A and B, if A exhibits positive deviation from Raoult's Law then why component B will also exhibit positive deviation? [closed]

Explain how and why is it necessary for component B to exhibit positive deviation from Raoult's Law as well?
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pH for an HA/NaA solution using a contour map

The following question has troubled me for a while now. A virtual weak acid $\ce{HA}$ dissociates as follows: $\ce{HA <=> H^+ + A^-}$ with the acid dissociation constant $K_\mathrm{a} = 10^{-3....
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Le Chatelier’s Principle chem [closed]

How would I answer a question like this on a test? Removal of one of the products of a chemical reaction has the effect of causing the reaction to go to completion. Explain this in terms of Le ...
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Le Chatelier’s principle Chemistry question [closed]

In caves we sometimes see large structures known as stalactites and stalagmites. These formations are made of crystals of the insoluble compound calcium carbonate, CaCO 3 (s), also known as limestone. ...
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Relative humidity and vapor-pressure in equilibrium

I have quite an unclear understanding of relative humidity. I am writing my understanding on the topic and please correct me wherever I'm wrong: What I understood: Let's say $\ce{H2O}$ has a (...
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Preparation of phosphate buffer of ph 7.4

Can I make a phosphate buffer of pH 7.4 starting with phosphoric acid and then adding NaOH until the pH reaches 7.4. What are the disadvantages of using this method over sodium phosphates?
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1answer
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How does the concentration of a liquid increase? [closed]

Here the answer is A, I thought that both solids and liquids had constant concentrations and only aqueous solutions and gasses have changes in concentration. how does adding extra ester increase the ...
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Ambiguity in the direction of dissolution equilibrium

The following reaction is usually carried out to test for the carbonate anion in an inorganic salt; $$\ce{CO3^2- +BaCl2/CaCl2 -> BaCO3/CaCO3(s) + 2 Cl-}$$ The resulting carbonate is stated to be an ...
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Physical Chemistry - Chemical Equilibrium [closed]

Q1) N2 (9) + 3H2(9) - 2NH3 (9) Assume K=6, for initial concentration of hydrogen and ammonia at 4 and 0.2 moles, respectively. Calculate for what initial value of nitrogen concentration, the extent of ...
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Standard Gibb's Free energy change, standard state and equilibrium

I just want to confirm if I am right in thinking that: statement: When a reaction in standard state is in equilibrium, then equilibrium constant K=1 Reason: since in a equilibrium, $Q=K$ and $ΔG=0$. ...
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Why is the rate of absorption constant? [closed]

In a comparison between absorption and adsorption, absorption was stated to take place at a constant rate, as opposed to adsorption, which slows down as the system reaches equilibrium. How does ...
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Osmotic Pressure of Aqueous Solution

The osmotic pressure of an aqueous solution at $25$ Celsius is $92.0$ $kPa$. Calculate the boiling point of the solution. (Assume that the density of the solution is $1.0$ $g/mL$, ignore the mass of ...
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reversible reactions and equilibrium

I recently began learning about equilibrium. I was taught that in a reversible reaction amounts of reactants decreases and that of products increases. I understood this simply as reactants react to ...
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How can one determine the order of equilibrium constant for aromatic compounds? [closed]

I have tagged a question, The whole point is- what makes pyridine have more Kc
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1answer
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Enthalpy in the van't Hoff equation

In the van't Hoff equation, why do we say that the change in enthalpy at standard pressure is constant? My book derives the equation for a mixture of ideal gases reacting with each other. The proof ...
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Complex formation in water and Henry's law

I've been trying to solve the following problem for a while now. Consider a mixture of two different gases ($A$ and $B$) for which Henry's law holds. When gas molecules $A$ and $B$ do not interact ...
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1answer
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Partial pressure of gases in a container with a piston

I've been having problems with the following problem. Figure 1. A container with a piston like that shown in Figure 1 is filled with $0.10$ $mol$ of Ar and $1.00$ $mol$ of water (liquid and vapor). ...
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Equilibrium in Gas Phase and Pressure

In one task/example there is gas phase reaction and it is said that reaction takes place at pressure of 1 bar and standard Gibbs energy of reaction is needed to be calculated. In this task 1 bar is ...
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1answer
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Equilibrium constant expression for an acid base reaction

While reading an organic chemistry textbook I saw the following Formula for calculating equilibrium constant of an acid-base reaction Consider following acid base reaction in which $\ce{HA}$(reactant ...
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Why does According to Le-Chateliers principle, adding heat to solid and liquid in equilibrium will cause the amount of solid to decrease

According to Le Chatelier's Principle the external changes must be counteracted but in this scenario the external factors causes the amount of solid to decrease because of obviously melting but if Le ...
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1answer
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In an equilibrium, why are partial pressures not affected by the coefficients of the balanced equation?

It's probably easiest for me to explain in an example. For the following reaction: $$\ce{2NOBr(g) <=> 2NO(g) + Br2(g)}$$ At equilibrium, if the partial pressure of $\ce{NOBr}$ was 6 atm, the ...
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1answer
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The effect of dilution on the rate of a system in equilibrium

I'm attempting to answer a question from my textbook, however the answer that the textbook provides doesn't make sense to me. In my mind, this dilution would instantly decrease the concentration of ...
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Calculating electric reduction(or oxidation) potential for complex ion formation equation?

I would like to calculate the standard electric potential($E°$) for the following equation. $$\ce{Pt^{2+}(aq) + 4Cl-(aq) → [PtCl4]^{2-}(aq)}$$ $K_f = \pu{1.0 * 10^16}, T =\pu{ 298K}$ I figured out $ΔG°...
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Equilibrium composition of methane–water system under given conditions

Calculate the equilibrium composition of a reactive system consisting of an equimolecular mixture of $\ce{CH4}$ and $\ce{H2O}$ at $\pu{900 K}$ and $\pu{1 atm},$ considered to be an ideal mixture of ...
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Why do chemical reactions attain equilibrium? [duplicate]

In the chapter 'Chemical Equilibrium', I studied that chemical reactions tend to attain equilibrium. But my question is why? Why do chemical reactions attain equilibrium? Is there any reason why they ...
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How do I comment on the Gibbs energy values standard and reaction in different situations? [closed]

I have the following graphs: Taking into account the following graphs, how do I comment on the Gibbs energy values standard and Gibbs energy of reaction in different situations (a, b and c), and how ...
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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 is degree of dissociation used to estimate strength of an acid?

Problem Which of the following will give strength of acid? A) pH B) Normality C) Degree of dissociation D) Dissociation constant Answer Question If pH is not considered as a metric to assess the ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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