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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Equilibrium-Get Chemistry [on hold]

Nitrogen dioxide is one of the many oxides of nitrogen (often collectively called "NOx") that are of interest to atmospheric chemistry. It can react with itself to form another form of NOx, dinitrogen ...
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63 views

What would be the concentration of products in this calcium producing system?

I wanted to figure out a way to make calcium metal with potassium oxide. $\ce{K2O}$ undergoes disproportionation at $\pu{350-430 °C}:$ $$\ce{2 K2O -> K2O2 + 2 K}$$ Now, if I mixed in $\ce{CaO}$ (...
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71 views

Is it possible to have only liquid in a closed container?

I recently read an answer by Aman Rusia for this question: Is a liquid in a container always in equilibrium with its vapour? In it, they say that You can't have a container filled with only ...
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How can I calculate the equilibrium of a reduction reaction? [closed]

I'd like to calculate the equilibrium in reducing the metal in a salt with a more reactive metal, e.g. $$\ce{HgSO4 + Pb → Hg + PbSO4}$$ Which as a side note, I know can only happen at low ...
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1answer
33 views

Calculating partial pressure equilibrium constant Kₚ given initial pressure and equilibrium pressure

A reaction $$\ce{A(g) <=> B(g) + C(g)}$$ happens in constant volume and constant temperature. The reaction starts only with gas $\ce{A}$ (no $\ce{B}$ or $\ce{C}$) with given pressure $...
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176 views

Why is the equilibrium constant unitless?

I read that the equilibrium constant is unitless because the molar activities of each of the species are used in the equilibrium expression, not the actual concentrations themselves. I understand that....
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1answer
38 views

Is “mass-action ratio” identical to “reaction quotient?”

Mass-action ratio Reaction quotient According to their definitions expressed in the above Wikipedia articles, these two concepts seem to be totally identical. Is that true? If not, what is the ...
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How can I calculate the equilibrium between several reactions?

If I mix xNaOH + yCdCl2 + zZnCl2 in an aqueous medium, how can I calculate the final equilibrium quantities of the resulting salts (which I suppose may be the following): Q1 NaOH Q2 CdCl2 Q3 ZnCl2 Q4 ...
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Equivalents Triethylamine in Swern-oxidation

Hey folks, so I've been wondering why the use of 5 equivalents of Et3N in this case of a Swern-oxidation is necessary. I have done this reaction succesfully quite a few times now, but all the ...
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28 views

Reactivity Series vs Equilibria? [closed]

I'm trying to grasp various aspect of the concept of reactivity series. Will more reactive elements displace less active elements until they have been entirely displaced, or is there an equilibrium ...
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25 views

Are there any exceptions to Le Chatelier’s principle? [duplicate]

Peter Atkins says In introductory chemistry, we meet the empirical rule of thumb known as Le Chatelier’s principle: When a system at equilibrium is subjected to a disturbance, the ...
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45 views

Finding the temperature at which the system reaches equilibrium

I’m really stuck on this problem. This involves dissolving Borax: $$\ce{Na2B4O7•10H2O(s)<=>2Na^+(aq) + B4O7^2-(aq) + 10H2O}$$ $$\begin{align}\Delta H&=\pu{109 kJ/mol} \\ \Delta S&= \pu{...
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Changing conditions of gaseous mixture

A gaseous mixture of $\ce{NO2}$ and $\ce{N2O4}$ is sealed in 4 identical vessels with movable pistons. When the conditions are modified as described in 1) to 4), in which condition does the molar ...
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22 views

Shift of Equilibrium

A friend of mine stumbled upon this question while revising equilibrium. Apparently the answer is A. The answer obviously cannot include adding a catalyst. Furthermore, according to le Chatelier's ...
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1answer
49 views

What does it mean for chemical reaction network to be in equilibrium?

What does being in "equilibrium" mean for a set of chemical reactions? If we have some number $n$ of $\ce{A}$ molecules and $m$ of $\ce{B},$ and the following reaction where $\ce{A}$ and $\ce{B}$ can ...
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83 views

Equilibrium constant for a solid-solid equilibrium

Suppose there are two equations: $$ \begin{align} \ce{A(s) &<=> B(g) + C(s)} &\quad &K_1 \tag{R1}\\ \ce{B(g) &<=> D(s) + E(s)} &\quad &K_2 \tag{R2} \end{align}$$ ...
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119 views

How to explain disagreement between Le Châtelier's principle and the simplified Gibbs free energy equation?

For example, for the dissolution of a salt in water that is exothermic, heating the solution would drive the reaction towards the solid form of the salt according to Le Châtelier's principle. However,...
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62 views

How to calculate the variation of the standard reaction enthalpy for the CO, CO2, H2O, H2 equilibrium?

For the reaction $$\ce{CO2 (g) + H2 (g) <=> CO (g) + H2O (g)}$$ the equilibrium constant $K_p$ has a value of $0.534$ at $\pu{960 K}$ and $1.571$ at $\pu{1260 K}$. Calculate the variation of ...
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1answer
62 views

How do I write a procedure for creating a buffer?

I need to write an original procedure with exact numbers for creating a buffer: Create a buffer using $\ce{CH3COOH}$ and $\ce{CH3COONa}$ that has a $\pu{pH}$ of exactly $3.75$. A $\pu{50 mL}$ ...
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74 views

Do maxima in Gibbs energy also correspond to equilibrium positions?

ΔrG=(∂G/∂ξ ) at constant p and constant T, where ξ is the extent of reaction. By Second Law implication, ΔrG= 0= (∂G/∂ξ ) at equilibrium. If we consider a graph of G against ξ, this would mean we ...
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How can equilibrium lie to one side ? Surely it’s not at equilibrium anymore? [closed]

Surely they’re not at equilibrium any more? I understand that a favourable condition can make a reaction in one direction go faster, but then surely either the forward or backward reaction is faster ...
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1answer
176 views

How does increase in volume change the speed of reaction in production of NO2?

$$\ce{2 NO + O2 <=> 2 NO2}$$ I understand that increasing the volume $×2$ means lower pressure so production of $\ce{NO2}$ is slowed down, but when asked how to express this mathematicaly I can'...
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67 views

Freezing point of solution

It's stated in my textbook that at the freezing point, the vapour pressure of the solid phase equals the vapour pressure of the liquid phase. In a mixture, since the vapour pressure of the solution is ...
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1answer
98 views

Why is the dissociation reaction of acetic acid in water initially endothermic and then exothermic?

Why is the dissociation reaction of acetic acid in water initially endothermic as temperature is increased and then becomes exothermic as it is increased further? My understanding from Le Chatelier's ...
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21 views

What happens to reaction quotient and equilibrium constant when pressure changes?

For example, considering $\ce{N2 (g) + 3H2 (g) <=> 2NH3 (g)}$ I learned that, for example, if I increase the pressure, the equilibrium constant $K_\mathrm{c}$ is not affected but the ...
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Adding pure solid/liquid in heterogeneous equilibrium [duplicate]

If I have the heterogeneous equilibrium $$\ce{aA(s) + bB(g) <=> cC(g) + dD(g)}$$ I understand that the equilibrium expression is $$K_c = \frac{[\ce{C}]^c[\ce{D}]^d}{[\ce{B}]^b}$$ and that $\...
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1answer
64 views

Henry law and equilibrium

Is Henry's law a consequence of the equilibrium between a substance S in aqueous phase and the same substance S in gaseous phase? What I mean is, is it correct to treat Henry law as a manipulation of ...
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2answers
48 views

Reaction quotient and Gibbs free energy at the start of a reaction

According to the equation 33 above, shouldn't be all the reactions be spontaneous initially? Because the reaction quotient Q, is zero at the start of the reaction and logarithm of Q makes it a very ...
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1answer
63 views

K in Gibbs free energy

When we write for an equilibrium that $$\Delta G^\circ = -RT \ln(K)$$ Which type of $K$ , ie is it $K_\text{concentration}, K_\text{pressure}$ or $K_{\chi}$ because all these have different numeric ...
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39 views

Can a cation form a bond with only the oxygen in hydroxide ion?

$$\ce{Al2O3 + 2 NaOH → 2 NaAlO2 + H2O}$$ In this reaction between an amphoteric oxide and a base, I do not understand how $\ce{Al}$ makes a bond with oxygen atoms since the water is found in the ...
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Le Chatelier's Principle Having No Effect

Consider the following equilibrium system: $$\ce{2 IBr(g) <=> I2(g) + Br2(g)}$$ Would a decrease in the volume of the system effect the equilibrium? I think it would not affect the ...
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332 views

If change in free energy (G) is positive, how do those reactions still occur?

I was doing a couple of problems for homework: Calculate $K_\mathrm{sp}$ of $\ce{AgI}$ at $55.0\ \mathrm{^\circ C}$ Calculate $K_\mathrm{b}$ of $\ce{NH3}$ at $36.0\ \mathrm{^\circ C}$ I have to use ...
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1answer
46 views

What happens if at equilibrium pressure is increased by decreasing the volume? [duplicate]

I think, according to Le Châtelier's principle both the conditions i.e. increasing the pressure and decreasing the volume must shift reaction towards the side on which there are less amounts of ...
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2answers
78 views

pH of strong acid weak acid mixture [closed]

Question: $\ce{H2S}$ ($\pu{0.1M}$; $K_\mathrm{a} = 1.2×10^{-20} $) and $\ce{HCl}$ ($\pu{0.3M}$) with same volume are mixed together. What is the resultant $\mathrm{pH}$? My approach: Let the volume ...
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Common ion effect

Let $\ce{HA}$ ($x$ molar) be a strong electrolyte and $\ce{HB}$ ($c$ molar) — weak electrolyte. As $\ce{HA}$ is strong electrolyte, it dissociates completely: $$ \begin{array}{lcc} \ce{&HA &-&...
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Amount of benzoic acid required to alter pH of a NaOH-solution

I am trying to do a practice problem but I can't figure it out: How many grams of benzoic acid needs to be added to 0.10 l of a NaOH-solution with a concentration of 1.0 mM to reduce the pH of said ...
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1answer
80 views

Methyl Orange Indicator-Reason for small amount of NaOH [closed]

I used methyl orange as my indicator to titrate a weak acid: At first, I added 3 drops of methyl orange to a solution of the weak acid, $\ce{CH3COOH}$, and the solution turned red. Then, after ...
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1answer
41 views

Calculating molecular weight of an acid based on given values of mass, volume, pH and pKa

This is what I thought was an easy problem but according to a given answer I am doing it wrong: $\pu{11 mg}$ of a monoprotic acid was dissolved in $\pu{0.5 l}$ of water. The resulting $\mathrm{pH}$ ...
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1answer
91 views

How to calculate the equivalent mass of Na2S2O3? [closed]

Let us consider the following reaction $$\ce{I2 + 2 Na2S2O3 -> 2 NaI + Na2S4O6}$$ Now, in order to calculate the equivalent mass of $\ce{Na2S2O3}$, first I need to calculate it's $n$-factor which ...
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1answer
48 views

Equilibrium constant for a multi-step reaction [closed]

If a reaction proceeds in steps, is the equilibrium constant of every step taken into account to arrive at the final constant? Or can we just calculate equilibrium constant for the overall reaction ...
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How addition of a soluble salt affects equilibrium involving precipitation with a base sharing the same cation?

I have the following reaction at equilibrium: $$\ce{Ba(NO3)2(aq) + KOH(aq) <=> Ba(OH)2(s) + 2 KNO3(aq)}$$ Will there be a change in the equilibrium if the salt $\ce{KCl}$ is added? Will the ...
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1answer
120 views

How to calculate the equivalent weight of KMnO4?

Let us consider the following reaction $$\ce{2 KMnO4 + 16 HCl → 2 KCl + 2 MnCl2 + 8 H2O + 5 Cl2}$$ Now, in order to calculate the equivalent mass of $\ce{KMnO4}$, first I need to calculate it's $n$-...
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Given Kd find equilibrium concentrations of the reactants

$$\ce{Biotin + Avidin → Complex}$$ Biotin is a vitamin derivative that binds extremely tightly to avidin (a protein found in egg white) with a $K_\mathrm{d}$ of $\pu{1e-15 M}$. If you make a ...
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Correct Generalization for Adair Equation?

I know how to derive the Adair Equation for n binding sites the long way, writing n+1 mini equations and linking them to relate all sub $K_b$ values to $K_{b-intrinsic}$. Tried to find a general ...
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1answer
64 views

Reaction of HF in water [closed]

I was wondering, if we put $\ce{HF}$ into a glass of water the acid will be dissolved according to this reaction: $$\ce{HF->F- + H+}$$ Now there is a proton travelling across the water. All $\ce{...
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1answer
39 views

Calculating pH of weak base and strong acid: Why is K(a) not required?

Question: 35mL of 1.5M $\ce{HCN}$, a weak acid(K(a)= $6.2*10^{-10}$) is mixed with 25mL of 2.5M $\ce{KOH}$. Calculate the pH of final solution. The solution given in my textbook is as follows:- $\ce{...
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1answer
29 views

When there is an increase in temperature, how is the pH of the ocean affected? (Question is related to ocean acidification)

This is my current understanding: Ocean acidification is the result of atmospheric $\ce{CO2}$ dissolving in the ocean's water. When this occurs the $\mathrm{pH}$ of the ocean decreases (from the ...
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3answers
49 views

Which of the following options are correct? [closed]

The equilibrium constant $K$ for the reaction $\ce{2HI <=> H2 + I2}$ at room temperature is $2.85$ and at $\pu{698 K}$ is $0.014$. This implies that: a) $\ce{HI}$ is exothermic compound b)...
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1answer
33 views

pKa value of an indicator

Can we deduce the actual value of $\mathrm{p}K_\mathrm{a}$ of an indicator if the $\mathrm{pH}$ range has been given? I know that $\mathrm{pH}$ range is physically the range of values over which an ...
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23 views

Saturation dissolved oxygen level at pressure

The saturation level of dissolved oxygen in contact with a moist atmosphere is $$c = 0.21(p_\mathrm{atm} - p_\mathrm{vap}) K_\mathrm{H} M$$ where the $p_\mathrm{atm}$ and $p_\mathrm{vap}$ are the ...