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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Effect of Temperature on pH of Water
The $K_\mathrm w$ is a function of temperature. It is $10^{-14}$ at $25\ \mathrm{^\circ C}$. When the temperature is $50\ \mathrm{^\circ C}$, the $K_\mathrm w$ can be calculated to be somewhere around ...
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Why does the ionic product of water remain constant after addition of non-neutral solute?
In my textbook, it is given that the ionic product of water $K_\mathrm{w}$ remains constant even when a non-neutral solute such as an acid is added to it.
$$K_\mathrm{w} = \ce{[H3O+][OH-]}$$
When a ...
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Acidity of hydrogen chloride in acetic acid
A question asked to find the $\mathrm pK_\mathrm a$ of $\ce{HCl}$ in acetic acid. The equation of $\ce{HCl}$ disassociating in water is: $$\ce{HCl + CH3COOH \leftrightharpoons CH3COOH2+ + Cl-}$$ I ...
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Quantum mechanical explanation for Le Chatelier's principle?
We know from basic chemistry that a reaction reaches equilibrium as described by Le Châtelier's principle. What's the quantum mechanical explanation to this principle? How a change in temperature/...
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How can a protein folding transition state have zero lifetime?
I'm doing a module on my Biochemistry course looking at protein folding, and in a discussion of [folding] transition states I was a little confused at the thought of a zero-lifetime transition state - ...
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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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What does “to the left” mean?
However, the concentration of hydronium and hydroxide ions will be very, very small; in fact, the equilibrium that's established in solution lies so far to the left, that only 18 in 1010 molecules of ...
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How to determine the pH of a mixture of two weak acids?
We have two solutions:
Solution 1 is $\ce{HCOOH}$, its concentration is $c_1 = \pu{10^-2 mol/l}$, its volume is $V_1 = \pu{50 ml}$, and its $\mathrm{pH}_1 = 2.9$.
Solution 2 is $\ce{CH3COOH}$, its ...
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What do curly brackets {} mean?
I learned that square brackets ex: $[\ce{H2O}]$ can be used to denote the concentration of water molecules in a fluid. The notation used much in equilibrium problems and such.
However, sometimes I ...
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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
$$[\ce{HF}] = 0.08~\...
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Derivation of van 't Hoff equation for temperature dependence of equilibrium constant
While I was reading about the usefulness of the quantity $\Delta H$, I found that it can be used to calculate the how the equilibrium constant varies with temperature. How can this be done?
Does it ...
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Why do solutions become saturated?
Why can a solvent dissolve only a particular amount of solute?
If we add more solute to the solution, the number of solute particles in contact with water increases. So rate of dissolution should ...
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Decomposition of calcium carbonate in a sealed vessel
For the equilibrium
$$\ce{CaCO3(s) <=> CaO(s) + CO2(g)}$$
$\Delta H^\ominus = 178\ \mathrm{kJ\ mol^{-1}}$ and $\Delta S^\ominus = 160\ \mathrm{J\ mol^{-1}}$.
I'm asked to suppose that $1\ \...
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How to calculate partition coefficients?
Below is a transcript of this doubtful question:
A weak monobasic organic acid $\ce{HA}$ is soluble in both water
and $\ce{CHCl3}$. $\pu{500.0 cm3}$ of a solution of $\ce{HA}$ in $\ce{CHCl3}$, ...
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What is the correct unit for the equilibrium constant?
I have the following equation
$$K_a = \dfrac{c\alpha^2}{1-\alpha},$$
with units $c= \pu{mol/cm^3}$ and $\alpha$ is the same. I'm not sure how to get the correct units for $K_a$. What I have come up ...
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