Questions tagged [solutions]
This tag should be applied to questions dealing with solutions of any kind. A solution is a liquid or solid phase containing more than one substance where, for convenience, one (or more) substance(s) called the solvent is treated differently from the other substances, which are called solutes. If water is the solvent, then the more appropriate 'aqueous-solution' tag should (also) be specified.
978
questions
1
vote
1
answer
144
views
(Effective) number of molecules interacting with light to produce optical activity
The question is: How can I get a sensible and concrete (not relative) value for the number of molecules light has interacted with to cause an optical activity phenomenon?
Specifically, my issue in ...
- 11
1
vote
1
answer
2k
views
Mass of sugar that was added to the water (Raoult's law)
Water has a vapour pressure of $15.5~\mathrm{mmHg}$ at $25~\mathrm{^\circ C}$. An unknown amount of the non-volatile sugar glucose ($\ce{C6H12O6}$) is added to $1.31~\mathrm{kg}$ of water and the ...
- 55
3
votes
1
answer
2k
views
Acidic and alkaline salt solutions: why do some salt form acid/bases while others don't [closed]
I have a question regarding salts and their solutions. How come some salts, like sodium carbonate and ammonium chloride, produce acids/bases when dissolved in water? Moreover, how can you predict ...
- 140
2
votes
1
answer
72
views
How do these solutions "react"?
If I were to combine solutions of $\ce{(NH4)2CO3}$ and $\ce{HNO3}$ in water, the only ionic compounds that could form are $\ce{H2CO3}$ and $\ce{NH4NO3}$ right? But since both are soluble no ...
0
votes
0
answers
125
views
Different ion effect
I need to have the highest concentration of (bi)carbonate ions in a water solution.
Thus far, my only idea was to use Potassium Bicarbonate (safe and cheap) as it has the highest solubility but it ...
- 19
0
votes
0
answers
410
views
What happens to the attraction of glycerol to a positively charged acetate rod if water is added
I know that glycerol is more polar than water because it has stronger intermolecular forces and its also more viscous. If I were to add water to a glycerol solution, would the solution get less polar ...
2
votes
1
answer
4k
views
Number of grams of CO2 released from a carbonated water
The partial pressure of $\ce{CO2}$ gas in a bottle of carbonated water is $3.84\mathrm{~atm}$ at $25\mathrm{~^\circ C}$. How much $\ce{CO2}$ gas (in g) will be released from $0.5\mathrm{~L}$ of the ...
- 55
0
votes
1
answer
44
views
What does "at%" refer to in sol-gel method?
I'm reading on the preparation of ZnO thin films for UV stimulated emission and I found a method called Sol-Gel. During this I found a paragraph saying, " the ration Ag/Zn in the sol is 3 at%......". ...
- 11
6
votes
1
answer
20k
views
What is the solvent and what is the solute?
This question is and I am learning about mixtures, solutions, solutes, solvents, and other terms related to these words.
I know that a solute is the substance being mixed with or dissolved into the ...
- 71
0
votes
2
answers
2k
views
Is water a heterogeneous molecule? [closed]
My question is based upon the statement found here:
an element may be homogeneous on a larger scale, compared to being heterogeneous on a smaller scale. This is known as an effective medium ...
- 383
1
vote
0
answers
443
views
Enthalpy of mixing in a regular solution
In a mixture of $A$ and $B$ where $A$ and $B$ are randomly mixed and the average coordination number is $z$. If there are $n_B$ molecules of $B$ in the mixture these will be in contact with a total of ...
- 9,676
0
votes
0
answers
88
views
How to quantify the amount of paracetamol present
What is the most accurate way of determining the number of moles of paracetamol from a solution, mixed with acid or base?
I do not have access to more advanced laboratory methods like liquid ...
1
vote
1
answer
1k
views
Entropy of mixing
$$S=k_\mathrm B\ln\mathit\Omega$$
For the mixing of two types of molecules:
$$\mathit\Omega=\frac{N!}{N_1!N_2!}$$
Therefore, subbing in and using Stirling’s approximation ($\ln{N!}=N\ln N-N$):
$$\...
- 9,676
4
votes
1
answer
51
views
Kinetics of air evolving from water on heating
Is there a simple relationship describing the kinetics of air evolving from water on heating?
For example, if I let water at room temperature and pressure saturate with air, it should have some ...
- 1,662
12
votes
2
answers
11k
views
Why does shampoo lather much more the second time it is applied?
When I shampoo my dirty hair, the first time it does not lather very much. The second time it lathers a lot. Why is this?
- 173
0
votes
0
answers
27
views
How to sequester Na+ which prohibits the formation of a micro-emulsion in solution
I am mixing alkaline solutions ($\ce{Na2CO3}$) with crude oil containing carboxylic acids to create micro-emulsions. The carboxylic acids react with the alkaline moieties to create an in-situ ...
4
votes
3
answers
557
views
Finding equilibrium concentrations in solution from initial reagent concentrations and equilibrium constant
We have the following reaction:
$$\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 $\ce{A}$...
- 1,865
14
votes
3
answers
32k
views
Why iron reacts differently with concentrated and dilute sulfuric acid?
When $\ce{H2SO4}$ is dilute,
$ \ce{Fe +H2SO4 -> FeSO4 + H2} $
and when $\ce{H2SO4}$ is concentrated,
$\ce{3Fe +8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 +8H2O}$
What made the reaction with ...
- 283
1
vote
2
answers
5k
views
Can I extract water from diethyl ether to get anhydrous diethyl ether?
I am trying to get anhydrous diethyl ether. So, I am considering using a condensor to heat up diethyl ether and extract water. Would this method work?
- 31
0
votes
2
answers
4k
views
Getting the molality of a solution given molarity and density
If a solution of $\ce{HNO3}$ has a molarity of 16 and a density of
$1.42\ \rm{g/mL}$, what is the molality of the solution?
Well, a molarity of 16 means that there are 16 moles of solute for every ...
- 825
0
votes
2
answers
2k
views
Get the molar mass of an unknown liquid in a dissolution
A dissolution has $10$ g of some unknown liquid and also $90$ g of
water. The freezing point of this dissolution is $-3.3\, ^\text{o}$C.
What is the molar mass of the unknown liquid in g/mol?
Alright....
- 825
5
votes
2
answers
16k
views
Solubility in carbon tetrachloride
Which of these substances is more soluble in $\ce{CCl4}$?
$\ce{CH3F}$
$\ce{I2}$
$\ce{Na2SO4}$
$\ce{HCl}$
How do I even solve this kind of exercise?
My guess is that $\ce{CCl4}$ is ...
- 825
2
votes
1
answer
170
views
Ion pair definintion in chemistry
I read in the journal of organic chemistry:
A less striking, but nonetheless significant, attenuation of the reactivity of phenyl selenide anion can be achieved by varying the counterion and/or the ...
- 51
2
votes
0
answers
82
views
If a conductivity meter is calibrated with aqueous standards, can it be used to measure the conductivity of an organic-based solvent system?
Trying to figure out if the calibration solutions for a conductivity probe/meter must be of a similar nature to the system which will be measured. I can only find aqueous calibration solutions online, ...
- 99
1
vote
2
answers
626
views
Calculate concentration gradients in FPLC
Our FPLC works with two solutions:
A: 20 mM Tris.HCl, 0.2 M NaCl, pH 7.8
B: 20 mM Tris.HCl, 1.6 M NaCl, pH 7.8
I'm interested in sample volume from 102 mL to 117 mL. The FPLC will have a linear ...
- 642
1
vote
2
answers
4k
views
Molarity is dependent on temperature?
Okay I know that as the temperature rises the number of particles in a given volume decreases. The molar volume likewise increases. So the number of molecules per liter would decrease as the ...
- 2,087
7
votes
2
answers
276
views
Is there a potentiometric method for monitoring salt formation in organic solvent?
I work in a pharmaceutical R+D lab, and currently aim to develop a validatable potentiometric method for determining the optimal amount of acid to add to a basified small organic molecule for ...
- 99
3
votes
2
answers
5k
views
What does all chromatography have in common?
We're learning about chromatography in class, and I'm confused about all the different types (e.g. those that separate liquid-liquid solutions vs. those that separate liquid-solid solutions vs. those ...
- 465
1
vote
1
answer
9k
views
p-value for ions in a solution?
The question in my class notes read as:
Calculate the p-value for each ion in a solution that is $2.00 \times 10^{-7}\ \mathrm{M}$ in $\ce{NaCl}$ and $5.4 \times 10^{-4}\ \mathrm{M}$ in $\ce{HCl}$....
- 229
3
votes
1
answer
4k
views
Calculating the concentration of a diluted solution
I have this problem:
From a stock solution of initial concentration of $10~\mathrm{mg/l}$, I take $2\,\mathrm{ml}$, and then I add $10\,\mathrm{ml}$ of distilled water.
I am supposed to calculate ...
- 161
2
votes
1
answer
242
views
History of octanol-water partition coefficient
We are aware that one of the basic information about a material is the logP value it has. The logP is worked out from the partitioning between the octanol and the water phases. Does anyone know who ...
- 273
1
vote
1
answer
117
views
Weight Percent of Solutions Given Without Units
I have been performing haloform reactions using sodium hypochlorite. The most available source is common household bleach, which is a solution of $\ce{NaClO}$ in water. The bottles invariably give a ...
2
votes
3
answers
385
views
Something about the idea of Molarity is confusing me
Okay, so molarity is defined as moles of solute per liter of solution. It is used to describe the concentration. So in the lab, when I see a bottle labeled something like $\mathrm{3.5~M}~\ce{H2SO4}$, ...
4
votes
1
answer
5k
views
Is there a certain amount of titrant that is ideal?
For an AP chem lab dealing with determining the amount of citric acid in orange juice by titrating with NaOH, one of the discussion questions goes like this:
Choose an amount of beverage to be ...
- 90
1
vote
1
answer
79
views
Formalin fallen out of solution
Is there a way to bring back into solution a bottle of formalin that has crystallized? The bottle has been stored for several years at room temperature.
Thanks in advance.
- 11
3
votes
1
answer
677
views
Is a supersaturated solution still a solution?
Given that a solution must be a homogenous mixture, and having crystallized solids at the bottom of a solution is most definitely not homogenous, can a supersaturated solution still be technically ...
- 151
15
votes
2
answers
7k
views
Justification for Freezing Point Depression & Boiling Point Elevation in Solutions?
I was wondering if the following justification for freezing point depression and boiling point elevation are conceptually correct. The reason why I ask this question is because I have been self ...
- 161
0
votes
2
answers
6k
views
What is the difference between reacting and dissolving?
When one chemical is added to another how would we come to know whether the compound dissolves in it or reacts with it? For example $\ce{AgNO3}$ dissolves in $\ce{CCl4}$ whereas it could also have ...
- 380
0
votes
0
answers
460
views
acids, bases, salts, etc
All the chemical compounds can be categorized as acids, bases, and neutral compounds.
There are different theories, namely Arrhenius Theory, Brønsted-Lowry Theory, Lewis Theory, which define the acids ...
- 125
4
votes
1
answer
345
views
Making a non-CN dissolved gold solution ideal for electroplating
I've had success electroplating $\ce{Ni}$ and $\ce{Cu}$, but interestingly never $\ce{Al}$. My focus here is on plating with $\ce{Au}$, specifically onto an $\ce{Ni}$ surface.
In general from my own ...
- 3,564
8
votes
2
answers
1k
views
Is there a soluble salt, or compound that when dissolved in water results in a solution with density less than pure water?
Generally water soluble salts tend to 'fit between' the molecules of water such that the volume of the resulting solution does not increase much relative to the volume and added mass of the salt. So ...
- 2,743
1
vote
1
answer
3k
views
Why are the reactants in the solubility product constant multiplied by their coefficients and raised to the power of their coefficients?
It is probably easiest for me to explain the question in an example. Consider the following chemical reaction:
$\ce{MgF2(s) -> Mg^{2+} (aq) + 2F- (aq)}$
Plugging this into the formula for the ...
- 90
5
votes
1
answer
2k
views
Is the density of the solution significantly different from the density of the solvent?
I am working on a mathematical model for the dissolution of coffee in water. I need to know some precise details about the effects of dissolution on the density of the mixture of the substances (that ...
- 151
25
votes
4
answers
29k
views
How does oil on the surface of water prevent rust?
I distinctly remember a side-by-side comparison from a book where there are two nails submerged in water, in two beakers: one nail had a layer of oil on top of the water, and that nail didn't rust; ...
- 1,202
7
votes
1
answer
861
views
Can I equalise osmotic pressure using two different solutes?
I understand that there is a pressure gradient between an aqueous solution, e.g. salty water, and, say, pure water due to osmosis. My question is, is it possible to match or almost match, the osmotic ...
- 305
5
votes
1
answer
9k
views
What is the lethal dose ( LD50 ) of coffee?
Of course, there are many types of coffee, so I would like a range of lethal dose amounts for the average human, from the mildest of lattes to the most hardcore of espressos.
Pure caffeine's lethal ...
- 2,207
0
votes
1
answer
378
views
Reduced-pressure (vacuum) evaporation/drying of 15 liters of aqueous solution
I have 15 liters of aqueous solution inside an aluminum stock pot which rests upon a hot plate. I want to reduce the boiling point from 150°C to 100°C using reduced pressure.
What is the most ...
2
votes
1
answer
10k
views
Using vapor mole fraction and pressure to determine liquid mole fraction
I am studying Chemistry by Zumdahl and Zumdahl (9th edition) and I have come across a question in Chapter 11 that I can't figure out the explanation for:
Liquid A has vapor pressure x , and liquid B ...
- 41
5
votes
1
answer
453
views
The partition coefficient for a chemical species across a membrane
What factors influence the partition factors across a membrane for a chemical species? Wikipedia defines the partition coefficient as:
In the physical sciences, a partition-coefficient (P) or ...
- 233
-1
votes
1
answer
1k
views
Are concentrated salt solutions stable over time?
I have to use dilute salt solutions incredibly frequently, and it takes valuable time to make them from pure reagents every time I need them.
Are concentrated salt solutions fairly stable over time?
...
- 242