All Questions
Tagged with equilibrium solutions
59
questions
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
10
votes
2
answers
1k
views
Apparent contradiction in the type of deviation of an ethanol-water mixture
For a mixture of $\ce{EtOH}$ and $\ce{H2O}$: $\Delta H_{\text{mix}} < 0$ (exothermic) and $\Delta V_{\text{mix}} < 0$ (volume contraction). This means that the unlike interactions are stronger ...
7
votes
4
answers
2k
views
Gibbs Free Energy of Solutes and Solutions
Using the equation $$\ce{CaSO4 (s) <=> Ca^2+ (aq) + SO4^2- (aq)},$$ and $\Delta H/\Delta S$ values, calculate $\Delta G$ at $50~^\circ\mathrm{C}$ when the solution is saturated with $\ce{Ca^2+}$ ...
- 71
6
votes
1
answer
111
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
$$D = \frac{C_\mathrm{A}(\text{ext})}{C_\mathrm{A}(\text{orig})}$$ ...
- 71
6
votes
1
answer
43k
views
Degree of association, van't Hoff factor and dissociation constant
$\ce{CH3COOH->CH3COO- + H+}$
\begin{array}{c|c c c}
\mathbf{Initial} & \mathrm{1~mol} & \mathrm{0~mol} & \mathrm{0 ~mol} \\\hline
\mathbf{Final} & \mathrm{1-\alpha ~mol}&...
- 719
6
votes
1
answer
731
views
If volatility depends on intermolecular forces, then why in Raoult's law, two substances have different volatility?
I have a doubt, Ideal solutions are solutions where intermolecular forces between solute-solute and solvent-solvent are nearly equal to solute-solvent. Since intermolecular forces between A-A = B-B, ...
- 181
5
votes
1
answer
643
views
Why do my equilibrium calculations on this HF/NH4OH buffer system not match those in literature?
I've been trying to reproduce Figure 2 from this research paper (full text available).
The Problem
However I can't seem to get the same values as in the paper. I did the math both by hand and with ...
- 161
4
votes
4
answers
4k
views
Why does the degree of dissociation change when we dilute a weak acid even though the equilibrium constant 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 ...
4
votes
3
answers
1k
views
Dynamic equilibrium in unsaturated solutions
One standard definition of equilibrium in beginner chemistry is that for a reversible reaction, (dynamic) equilibrium has been achieved when the rate of the forward and backward reactions are equal. ...
- 143
4
votes
3
answers
817
views
Finding equilibrium concentrations in solution from initial reagent concentrations and equilibrium constant
We have the following reaction:
$$\ce{A + B<=>2C +D}$$
The initial concentration of $\ce{A}$ and $\ce{B}$ are $\pu{1M}$ each. $K_c$ is $\pu{1.0E8}$. Find the equilibrium concentration of $\ce{A}$...
- 1,891
4
votes
1
answer
6k
views
Difference between freezing point and melting point
I do not understand why for mixtures freezing point is lower than melting point. Are not the two representing the same equilibrium between solid and liquid which we are approaching from two different ...
- 41
4
votes
1
answer
159
views
Why is the van ’t Hoff relation an approximation?
Lately, I've been looking and thinking about the fact that a professor told us in an advanced physiology lecture. When it came to mentioning osmotic pressure and the van ’t Hoff relationship
$$
\pi = ...
- 41
4
votes
1
answer
8k
views
How is the formula of mean activity coefficient derived?
The mean activity coefficient is defiend as follows:
$$\gamma_\pm = (\gamma_+\gamma_-)^{1/2}.\tag{1}$$
If Debye-Hückel equation
$$-\log\gamma_i = 0.5z_i^2\mu^{1/2}\tag{2}$$
is used, then the mean ...
- 143
3
votes
2
answers
2k
views
Calculate the titer of a solution
I hope this is the right place to ask. We have this exercise without solution
One litre of diluted sodium hydroxide solution (c = 0.15mol/litre) is
to be prepared in the laboratory. The titer from ...
- 423
3
votes
1
answer
1k
views
Solution to Raoult's Law for a volatile binary solution (no pun intended)
Raoult's Law
In a closed container, $$P_A=P_A^\circ x_A$$ where $P_A$ is the pressure of compound in gaseous phase, and $x_A$ is the mole fraction of the liquid component A in the liquid mixture. If ...
