All Questions
Tagged with equilibrium physical-chemistry
434
questions
34
votes
2
answers
190k
views
What would be the effect of the addition of an inert gas to a reaction at equilibrium?
Why does a dissociation reaction shift to the right with the addition of an inert gas?
- 989
33
votes
4
answers
69k
views
Why are solids and liquids not included in the equilibrium constant? What about in a reaction rate calculation?
Take for instance the reaction
$$\ce{H2(g) + I2(s) <=> 2HI(g)}$$
The equilibrium constant would not include the solid $\ce{I2}$, but why is this? I have read that its concentration is a ...
- 3,256
26
votes
4
answers
4k
views
Relation between chemical kinetics and chemical equilibrium
In my chemistry book, the law of chemical equilibrium is derived from the law of mass action:
For a reversible chemical reaction $$\ce{aA +bB\rightleftharpoons cC + dD}$$ where $a$, $b$, $c$ and $d$ ...
- 5,685
25
votes
2
answers
3k
views
Which equilibrium constant is appropriate to use?
I have learnt that the standard free energy change is related to the equilibrium constant of a reaction by,
$$\Delta G^\circ = -RT \ln K$$
Here, does $K$ refer to $K_p$ or $K_c$?
Also, please give ...
- 1,245
25
votes
2
answers
13k
views
Why does water dissociate to H3O+ and OH- rather than H+ and OH-?
Why does water dissociate to
$\ce{H3O+ + OH-}$
instead of $\ce{H+ + OH-}$?
This question came to surface when I was learning about acids and bases, and learned this definition:
$\mathrm{pH=}-\log_{10}[...
- 383
15
votes
2
answers
3k
views
Le Chatelier's principle: Are there any exceptions?
The way Le Chatelier's principle is presented in most introductory chemistry books (high-school) is as though it's an indisputable law of the physical world (in the sense that we're never shown an ...
- 18.8k
14
votes
4
answers
4k
views
Is there a reason for the mathematical form of the equilibrium constant? [duplicate]
Why are the two molarities multiplied and not added, and why is each raised to the power of the coefficient rather than multiplied by it? What is the reasoning behind this form? Was it simply ...
- 939
14
votes
2
answers
905
views
Apparent paradox in the formation of ice at room temperature
The formation of ice out of liquid water can be written down like this:
$$\ce{H2O (l) <=> H2O(s)}$$
We can calculate the change in standard Gibbs free energy (per mol substance) in the following ...
13
votes
3
answers
9k
views
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 $\ce{H+}$ ...
- 557
13
votes
3
answers
6k
views
Why exactly does precipitation occur?
In a solution, we have ions floating around but when we have a precipitate, they're arranged as they would be in a solid. This conversion should cause a decrement in the entropy of the system and ...
- 197
13
votes
2
answers
9k
views
Why does the equilibrium constant change on scaling the stoichiometric coefficients of a reaction?
I read in my textbook that if we multiply a chemical reaction by some factor(let's say $b$) its new equilibrium constant becomes $K^b$.But I don't understand why this happens..
What is the difference ...
- 141
13
votes
2
answers
2k
views
Why should a system try to reverse any change that has been done to it?
I understood Le Chatelier's principle perfectly but my question is: Why should a system try to reverse any change that has been done to it?
I understand equilibrium constant, mole concept and ...
- 1,161
13
votes
2
answers
4k
views
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 ...
- 7,402
12
votes
1
answer
43k
views
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 ...
- 780
12
votes
4
answers
9k
views
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 ...
- 863