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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.

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2answers
198 views

When making a calibration curve, do we have to use the wavelength at maximum absorbance?

If you are making a calibration curve for $\ce{CuSO4}$ where you plot absorbance against concentration, does the wavelength have to be exactly at the maximum of the peak? Or can it be somewhere else ...
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4k views

Is sodium acetate strong or a weak electrolyte?

Since it is formed of a strong base and a weak acid it should be a strong electrolyte but a chemistry teacher said that it is a weak electrolyte.....
3
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271 views

Is HDPE affected by long term exposure to methanol?

For at least several years I'be been storing various chloride solutions with methanol as a solute in Nalgene containers, which I believe are made from high density polyethylene (HDP). But recently ...
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3answers
6k views

How to determine electrolyte concentration in solutions?

The original question is here We've been given the sports drink vs orange juice challenge. To find out which has more electrolytes. I could test for conductivity but that alone wouldn't tell me ...
3
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1answer
636 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 ...
3
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1answer
114 views

Adding ethanol to louche

I'm watching MIT chemistry by Donald Sadoway. In one of his lectures devoted to solutions and phase separation, he performs experiments with absinthe. First he mixes absinthe with 5 $\times$ water ...
3
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2answers
617 views

Interpretation of miscibility curves

I stumbled across miscibility curves in the section Solubility of Liquids in Liquids (Organic Chemistry, by Wallwork and Grant) today. I'm not sure if my problem is with the way the content was laid ...
3
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2answers
2k views

Mass of salt required to make a 1.2 g/ml solution

I would like to make an NaCl and water solution with a density of 1.2 g/ml. How would you calculate the grams of NaCl required to make a 1000 ml solution? I have used density of mixture = (mass NaCl +...
3
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1answer
2k views

Effect of impurities on enthalpy of fusion of ice

When I freeze water with some impurities (1% NaCl by mass), the mixture seems to have a much lower enthalpy of fusion that pure water. The impurities cause the freezing point to depress to 0.6°C. I ...
3
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2answers
553 views

Colligative properties and sizes of particles

Why do colligative properties only depend on the number of particles and not the size? *My argument being that since the root cause of these properties is the occurrence of solute particles on the ...
3
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2answers
69 views

Understanding what is happening when something is dissovled

Let's start with a saturated solution of NaCl in water. At this point, any further addition of NaCl at the same T and P would not dissolve. However, if I then add another fully soluble salt (say AgNO3)...
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2answers
382 views

Dissolving in DMSO semantics

What does it mean when a substance (powder) is 'dissolved in DMSO and used at $\mathrm{5~\%}$' Does is mean that the substance is first dissolved in DMSO and then added to another solution where it ...
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3answers
1k views

What is the procedure to create stock solutions?

Until now to execute this recipe, each time i had to count those milligrams/Liter. An enough difficult procedure. I am posting here this question to help me understand the procedure of creating ...
3
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1answer
233 views

When are we justified in making assumptions in questions

The density at $20^\circ\mathrm{C}$ of a $0.500~\mathrm{M}$ solution of acetic acid in water is $1.0042~\mathrm{g/mL}$. What is the molality of the solution? The molar mass of acetic acid is $M(\ce{...
3
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1answer
251 views

Relation between freezing point depression and vapor pressure

My lab manual defines the freezing point as "The temperature at which the vapor pressure of the substance in its liquid phase is equal to its vapor pressure in the solid phase." It goes on to explain ...
3
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1answer
10k views

Why does ethanol and water mixture show positive deviation from Raoult's Law?

So, my teacher said, "For a solution to show positive deviation from Raoult's Law, it must have a compound which is lacking hydrogen bond and a compound which has hydrogen bond." This is because the ...
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3answers
1k views

Proof of Dynamic Nature of Equilibrium

Here is how my textbook proves that dissolution of solid in liquid is dynamic in nature. It considers the example of a saturated solution of sugar. It says that, Though the solution is in ...
3
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1answer
3k views

Does NaCl reduce the surface tension of water?

Does NaCl reduce the surface tension of water? And why? For example soap does it, and I was wondering if NaCl does the same.
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2answers
7k views

About pH of an aqueous solution of SO2

Probably we can have an aqueous solution of $\ce{SO2}$ by dissolving it in water, because we would have an equilibrium between $\ce{SO2(g)}$ and $\ce{SO2(aq)}$: $$\ce{SO2(g) <=> SO2(aq)}$$ How ...
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3answers
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Computer killed by insecticide; what compounds are likely?

A friend of mine sprayed "Black Flag Home Defense" insecticide under her computer. It died immediately. I'm trying to figure out why, and how fixable it might be. I found an MSDS, but it only says ...
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2answers
578 views

Mixing of powders to make stock solutions

For a solution such as: Luria-Bertani (LB) Broth: 10 g tryptone 5 g yeast extract 10 g of NaCl ($M = 58.44\ \mathrm{g/mol}$) q.s. to 1 l, pH to 7.2, autoclave. I would like to make a bulk amount ...
3
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1answer
108 views

Residual stress in polymer coatings

A paper talks about the residual stress when coating polymers. It says that residual stress is the sum of the "heat stress" (due to the difference in thermal expansion coefficients) and the "shrinkage ...
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1answer
775 views

Electric field effect on reactions

What would be the effect of putting a solution in a strong electric field? Would the reactions in the solution be affected? I'm thinking yes – lots (if not all) – chemistry is dependent on charge (...
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1answer
93 views

Flaw in my logic on Henry's Law?

It states mathematically $ p=Kx $ where $x$ is mole fraction of dissolved gas and $p$ is partial pressure of the gas. Dissolution of gases is exothermic, so with increase in temperature, solubility $x$...
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1answer
3k views

Differences between miscible and soluble

What are the differences between soluble and miscible? So far I found this (page 3 http://faculty.sites.uci.edu/chem1l/files/2011/03/D01MANmiscibility.pdf): soluble=solid dissolves into a liquid ...
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1answer
259 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 ...
3
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2answers
9k views

Diluting acetic acid to obtain a solution of pH 5 [closed]

What percent of a solution needs to be acetic acid for a particular $\mathrm{pH}$? I have 100% acetic acid, and want $1~\mathrm{L}$ of solution with a $\mathrm{pH}$ of 5. I've done some research, but ...
3
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1answer
292 views

Solve this mole fraction calculation with incomplete information

I am currently trying to solve a problem that seems quite simple at the beginning but the complexity reveals itself soon thereafter. The problem is the following: You mix a known mass of water ...
3
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2answers
1k views

What is hard and soft water and how does the process of dissolution work?

This is a very basic question about solubility, especially solution of table salt in water and solution of sugar in water. I have heard about terms like hard water, soft water, filtering of water to ...
3
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1answer
225 views

Why do acids usually completely react with bases?

When a neutralisation reaction happens, for example, $ \pu{100 mol l^-1}$ of $\ce{HCl}$ with $\pu{100 mol l^-1}$ $\ce{NH_3}$, why does all of the base and acid get converted to salt? Why isn't there ...
3
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1answer
11k views

What properties does a solvent with a high dielectric constant have?

My professor commented that water has a higher dielectric constant than alcohol. Okay, but on what basis? He didn't elaborate; he asked us which one seemed "more electric" and most answered water. ...
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1answer
2k views

Permanent suspension of cocoa powder into water

I have failed in permanently suspending cocoa powder into water. I have tried heat (212'f) and pressure (40 psi) into a sugar water solution (50/50). Also, powdered milk and evaporated milk have ...
3
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1answer
278 views

Condition for formation of azeotropes

Consider a binary azeotropic solution of two volatile components $A, B$. I wanted to try and find out the required concentrations of $A, B$ in the solution in terms of their vapour pressures. I tried ...
3
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2answers
328 views

Why does coke foam up when I add it to (cold) black coffee (no sugar, no milk)? [closed]

Album of the different gifs detailing this situation: Album of coke-coffee related gifs I thought that the answer would be similar to the ice-cream float situation, but I don't see what in the coffee ...
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2answers
2k views

How do we turn PTFE powder into a paste we can dilute in a solvent

We want to create a binder we can use in our filter elements that is PTFE based, so we need to somehow create a paste, we can thin down with a solvent that will still hold the PTFE in suspension, long ...
3
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2answers
682 views

Why is partial pressure used as a metric for oxygen in blood?

I know haemoglobin basically acts as an oxygen buffer. But when we talk about non-bound oxygen in blood (or water), we're referring to the amount of O2 in solution (aqueous state). From a biochemistry ...
3
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1answer
178 views

pH of a redox reaction between nickel(IV) oxide and silver

For the following reaction: $$\ce{NiO2(s) + 4 H+(aq) + 2 Ag(s) -> Ni^2+(aq) + 2H2O(l) + 2Ag+(aq)}$$ $$ E^\circ = 2.48\ \mathrm V$$ Calculate the $\mathrm{pH}$ of the solution if $E = 2.23\ \...
3
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1answer
47 views

vertically growing icicle

I made some "super" soap bubbles with my kids using the following ingredients: liquid dish soap tap water corn syrup We left the solution out over night last night here in Maine and the temperature ...
3
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1answer
701 views

What happens when a semipermeable membrane allows only one solute to pass through?

I'm essentially a medical student where we deal a lot with osmosis. But when we are taught, it is done generally with only a single solute in consideration. What if two different solutes are used on ...
3
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1answer
3k views

How to calculate the osmotic pressure of a sucrose solution?

The boiling point of an aqueous solution containing sucrose, $\ce{C12H22O11}$, is $101.45~^\circ\mathrm{C}$. Calculate the osmotic pressure of this solution at $35~^\circ\mathrm{C}$, at which the ...
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1answer
1k views

Molecular weight determination from freezing point depression

Which is the better solvent for molar mass determinations by freezing point depression, benzene or cyclohexane? Which is the better method for molar mass determination, freezing point depression or ...
3
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1answer
21k views

Can you find the mass of solvent with mass of solute, volume of solution, and solution density?

If you have, for example, $\pu{10 g}$ of a solute dissolved into $\pu{100 ml}$ of a solution, and the solution density is $\pu{1.5 g ml^-1}$, can you just multiply $100\ \mathrm{ml} \times 1.5\ \...
3
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1answer
741 views

What is the total concentration (in mol dm−3) of ions in each of the following solutions, assuming complete dissociation

$0.750\ \mathrm{mol\ dm^{-3}}$ solution of $\ce{K2CO3}$ (I believe is $2.25\ \mathrm{mol\ dm^{-3}}$) $0.355\ \mathrm{mol\ dm^{-3}}$ solution of $\ce{AlCl3}$ (I believe is $1.42\ \mathrm{mol\ dm^{-3}}$...
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1answer
110 views

Why is the maximal percent concentration of acids similar to their molar mass

Why is the usual percent concentration of a concentrated acid's solution similar to its molar mass? For example: ...
3
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1answer
154 views

metal salt solutions g/l means hydrate or anhydrous

I want to redo an experiment. They've used Nickel chloride: 40 g/L Nickel chloride can be bought in two forms: anhydrous ($\ce{NiCl2}$) and hydrate ($\ce{NiCl2....
3
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1answer
346 views

Properties of azeotropes

Consider two liquids with vapour pressures in pure form being ${P^o}_A$ and ${P^o}_B$. ${P^o}_B >{P^o}_A$ which implies liquid B is more volatile. If the liquids formed an ideal solution, then a ...
3
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1answer
711 views

Why any non polar compounds dissolve in nonpolar substance like Benzene what is the reason behind it? [duplicate]

In case of ionic solvent the ionic solute dissolve in it because due to polar nature of water it break the bond between the ions through hydration energy and the ionic solvent dissolve in it. So I ...
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1answer
3k views

Why do chloroform and benzene exhibit negative deviation from Raoult's law?

Chloroform is a polar molecule, and benzene is nonpolar. Shouldn't the chloroform-chloroform and benzene-benzene intermolecular forces be stronger than chloroform-benzene interactions (like dissolves ...
3
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1answer
263 views

How to determine fire hazard of heating ethylene glycol to dissolve borax and boric acid

I am looking to replicate instructions provided in the last paragrph of this article that requires dissolving borax (Sodium Tetraborate decahydrate ($\ce{Na2B4O7·10H2O}$)) and boric acid in ethylene ...
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1answer
1k views

Finding out pKa of acid from molar conductivity

I'm reading about the electrical properties of solution where there is a problem like that: The molar conductivity of $0.0250\ \mathrm M$ $\ce{HCOOH(aq)}$ is $4.61\ \mathrm{mS\ m^2\ mol^{-1}}$. ...