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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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2answers
139 views

How does pressure shift equlibrium

Here is a question from my practice problems: I know that the answer is A, but I don't know why. Is it because A has the most moles of gas on the left? thanks
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1answer
130 views

chemical equilibrium reaction for burned gases in engine

I do not understand how equation(3) occurs.(taken from the book Internal Combustion Engines by John B.Heywood) $$ $$ Consider a reactive mixture of ideal gases. The reactant species $M_a,M_b$ etc.and ...
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2answers
38k views

What does it mean for a reaction to favor the reactants/products?

(This example is purely hypothetical.) You have the reaction $$\ce{H2(g) + O2(g) <=> H2O2(g)}$$ at $T = 500\ \mathrm{K}$. The reaction reaches equilibrium at the following concentrations: $$\...
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1answer
23k views

Why x in equilibrium calculations can be “ignored”

You don't need to work out anything for me. I am just giving an example so you can explain something to me. For example: $$\ce{ClF3(g) <=> ClF(g) + F2(g)}\\ \ \ K_c=8.77\times10^{-14} \ \ @\ ...
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3answers
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How can the equilibrium shift, while Kc remains constant?

Consider the following reversible reaction. $$\ce{Cr2O7^2-(aq) + H2O(l) <=> 2 CrO4^2-(aq) + 2 H+(aq)}$$ What will happen to the position of equilibrium and the value of $K_c$ when more ...
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2answers
751 views

The reasoning behind predominance diagrams

Consider a one dimensional predominance diagram for a simple acid-base reaction: $$\ce{AH <=> A^- + H^+}$$ With equilibrium constant: $$K_a = \frac{[A^-]_{eq}[H^+]_{eq}}{[AH]_{eq}}$$ If I ...
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1answer
20k views

Calculating volumes of acid/base required to make buffer using pH and pKa

How would we use our $\mathrm{p}K_{\mathrm{a}}$ of the acid component of the buffer to calculate $\large \frac{[\ce{A-}]}{[\ce{HA}]}$? I know $$\mathrm{pH} = \mathrm{p}K_{\mathrm{a}} + \log\left(\...
5
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1answer
229 views

Equilibrium constant expression for heterogeneous equilibrium

Consider this reaction: $$\ce{CaCO3(s) <=> CaO(s) + CO2(g)}$$ for this, $K_c=\left[\ce{CO2(g)}\right]$ For a given temperature, $K_c$ will remain fixed. That means, the amount of $\ce{CO2}$ ...
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2answers
315 views

Equilibrium constant

I know that equilibrium constant depends on temperature and pressure. But according to Le Chatelier's principle when we change pressure of reagents the equilibrium is the same. Why?
2
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2answers
480 views

how many anions, acid molecules, hydronium cations, and water molecules in a certain volume of aqueous solution of an acid

The acid in question has pKa about 1.29. Density of 98% w/w solution is $d=1.323 \,\rm{g/cm}^3$. I would like to find the number of undissociated acid molecules ($\ce{HX}$), water molecules ($\ce{H2O}$...
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1answer
543 views

Salt Hydrolysis

Referring to this, when "hydrolysis of a salt" is its reaction with water: How is it that both the cation and anion of the salt are reacting in an equal amount with water? To state this specifically ...
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1answer
2k views

Ksp of Manganese Phosphate

I can't find the $K_{sp}$ value for Manganese Phosphate ($\ce{Mn_3(PO_4)_2}$) anywhere online. Has it been measured? What is it?
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1answer
202 views

Spontaneous inequilibrium in a gas in an isolated system?

Can an isolated system(of several phases) in equilibrium by itself move out of equilibrium? if a system contains for example an inflammable gas dispersed with another combustible gas such that the ...
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3answers
15k views

At equilibrium, the mass of reactants and products are equal. Does that mean the reaction stops?

This one is troubling me, and I even got it wrong in my exam: at equilibrium the mass of reactants and products are equal, does that mean the reaction stops? Please explain this one.
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1answer
13k views

How do you find the pH of a solution with a known pKa and Molarity?

How do you find the pH of a solution with a known pKa and Molarity?
5
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1answer
139 views

$K_{eq} $ vs $K_c$

I was wondering if there was a difference between $K_{eq}$ and $K_c$. I think they both refer to the Equilibrium Constant. If I'm wrong, could you please tell me the difference between the two? Thanks!...
4
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1answer
494 views

Interpreting equilibrium equations correctly

I've watched over this Khan video titled "Reactions in Equilibrium" and am still confused on the interpretation of equilibrium. Reactions in Equilirbium $\ce{N2(g) + 3H2(g) <=>2NH3(g)}$ ...
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1answer
521 views

Influence of solubility on the complexation constants at different pH values

Given some small chemical compounds whose solubility varies with pH, and in the case of compounds that can form complexes, I have seen that the complexation constant varies with pH. I think there ...
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0answers
772 views

Selectivity Coefficients of Ion Exchange Resins - Selectivity Reversal with TDS / Ionic Strength

I'm currently studying ion exchange resins and generally getting a bit stuck on some points of information which I do not fully understand / are not very well explained within the literature. I ...
7
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2answers
636 views

Chemical Equilibrium - Why do changes in pressure cause a shift in the ratio of products and reactants?

I understand Le Chatelier's principle and how every change to an equilibrium system causes an opposing reaction from the system. I also understand how, when pressure is increased, the equilibrium ...
8
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1answer
2k views

Simultaneous equilibria

Rephrasing: The following reactions are a small example of my big system $$(1)\ \ce{A + B <=> AB}$$ $$(2)\ \ce{AB -> CB}$$ $$(3)\ \ce{A -> C}$$ $$(4)\ \ce{C + B <=> CB}$$ with $...
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1answer
2k views

How do I calculate partial pressure here?

I need some help with partial pressures of reactions for a fuel cell project. The overall reaction for a fuel cell is $$\ce{H_{2} +\frac{1}{2}O_{2}->H_{2}O}$$ Which means that the mole fraction ...
7
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1answer
165 views

Are redox half-reactions “real”?

Are the half-reactions used in analyzing redox reactions a real thing or are they a conceptual shortcut? Is there a way to, however briefly, run a half-reaction by itself without the corresponding ...
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0answers
118 views

How much of the anion species is left over after the first precipitation?

Some barium chloride is added to a solution that contains both $\ce{K2SO4}$ ($\pu{0.050 M}$) and $\ce{Na3PO4}$ ($\pu{0.020 M}$). (a) Which begins to precipitate first: the barium sulfate or the ...
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4answers
20k views

Why are equilibrium constants unitless?

I haven’t quite reached the point where I can read a full-fledged text on chemical kinetics and thermodynamics yet, so bear with me, please. I’m wondering why a value like $K_\text{eq} = \frac{[\ce{...
8
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1answer
1k views

How to calculate the equilibration time of two connected chambers of salt solution, initially at different concentrations?

I am trying to build a system of two connected chambers, one of which is also connected to a cuvette, so I can perform a spectrometry experiment with different concentrations of $\ce{KNO3}$ solution. ...
12
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3answers
89k views

How do I calculate the degree of dissociation in equilibrium?

In my textbook, for calculating the percentage dissociation of $\ce{HF}$ for the given equation: $$\ce{HF + H2O <=> H3O+ + F-}$$ The solution is: Initial Concentrations $$[\ce{HF}] = 0.08~\...
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2answers
3k views

Problems in the concept of ionic equilibrium

While trying to understand the solution of a problem given in my text book, I realized I'm having some difficulty with the solution. The problem is as folows: The ionization constant of HF is $3.2 \...
13
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3answers
16k views

Reaction between silver nitrate and aluminum chloride

I googled a bit about what $\ce{AgNO3 + AlCl3}$ will yield and found out the following: $\ce{3AgNO3 + AlCl3 -> Al(NO3)3 + 3AgCl}$ Why is that? I know that $\ce{Ag}$ is higher up in the reactivity ...
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1answer
257 views

Why is it that the bigger the side-chain is, its hydrogen atoms tend to be more equatorial?

The most stable cyclohexane form is the chair conformation but on the other hand, the bigger the side-chain of the cyclohexane is, its hydrogen atoms become more equatorial rather than axial, which ...
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4answers
3k views

What software can calculate aqueous solution equilibria?

What software is available out there to calculate the equilibrium in a set of reactions in aqueous solution? In particular, I'm interested in software general enough to simulate things like titration ...
32
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4answers
18k views

Gibbs free energy-minimum or zero?

A reaction proceeds towards the direction of lesser Gibbs free energy (at constant $T$ (temperature) and $P$ (pressure)). So, we could say that Gibbs free energy at equilibrium is minimum. On the ...