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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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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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9 views

Effects of adding non-volatile solute in phase equilibrium

Suppose we have a phase equilibrium like this: H2O(l) ⇔ H2O(g) So the constant of equilibrium is the vapor pressure exercised by H2O(g), and it only changes with temperature. I don't understand why, ...
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9 views

How to describe the ionization equilibria of multiple ionizable species

For a weak acid [PB] in a buffered solution [H2PO4]/[HPO4] at pH 7.5 where: If some of the species [PB] was removed from the solution by partitioning on to an adsorbent, the equilibrium of [PB] ...
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2answers
153 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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0answers
30 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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2answers
118 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
67 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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19 views

carbon dioxide concentration of water [on hold]

If you let 10L of distilled water sit at atmospheric pressure, how much $\ce{CO2}$ will it contain in ppm when it reached it equilibrium with the air? (Assuming the air contains 350 PPM of $\ce{CO2}$...
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1answer
28 views

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

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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2answers
45 views

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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1answer
37 views

Buffer Systems, K(NH2)2 and HCL [closed]

25 .00ml of 0.100M R(NH2)2 with $Kb1=1*10^{-4}; Kb2 = 1*10^{-7}$ is mixed with amounts of .100M HCL a.) 0 ml b.) 5ml c.)10ml d.)12.5ml e.)25.00ml f.)37.50ml g.)50.00ml h.)60.00ml What is ...
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37 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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49 views

JEE Main Question - Find the Partial Pressure of Ammonia at equilibrium [closed]

Consider the reaction, N2(g) + 3H2(g) ⇌ 2NH3(g) The equilibrium constant of the above reaction is Kp . If pure ammonia is left to dissociate, the partial pressure of ammonia at equilibrium is given ...
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1answer
24 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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4answers
178 views

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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20 views

Increasing Solid in equilibrium [closed]

But when we increase the amount of liquid H2O in a closed system, doesn't this increase the pressure? Why this pressure is not increasing the concentration of gas H2O?My question was from this ...
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1answer
184 views

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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2answers
133 views

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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2answers
38 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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0answers
43 views

Mass-Charge balance equations [closed]

How to write mass balance equations and charge balance equations of the solution composed of $\pu{0.1M}\text{ }\ce{ NaH2PO4}~ \text{and}~\pu{0.05M}\text{ }\ce{ Na2HPO4}$? After writing the equilibria ...
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1answer
66 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
70 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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1answer
91 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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2answers
857 views

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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2answers
58 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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1answer
44 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 ...
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1answer
33 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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2answers
133 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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1answer
44 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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37 views

Why does K3PO4 not form a precipitate in an Fe(SCN)2+ equilibrium system?

In an experiment investigating Le Chatelier's principle, no change was observed with the addition of potassium phosphate. My understanding is that Fe3+ and PO43- ions should form insoluble FePO4.The ...
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1answer
72 views

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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2answers
826 views

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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43 views

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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2answers
61 views

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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1answer
31 views

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
73 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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1answer
69 views

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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22 views

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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1answer
54 views

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. ...
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1answer
53 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
71 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
29 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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1answer
84 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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2answers
229 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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2answers
62 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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40 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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2answers
49 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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30 views

Using Maxwell–Boltzmann distribution in reacting systems

In the book Physical Chemistry, a Molecular Approach by Simon and McQuarrie, the have used the Maxwell–Boltzmann distribution for velocity of molecules to estimate the the rate constant of a reaction. ...
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2answers
52 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)}$...