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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2
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1answer
1k views

Relative lowering of vapour pressure

Why is lowering of vapour pressure (Po - Ps) temperature dependent? And why is relative lowering of vapour pressure (1 - Ps/Po) independant of temperature?
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1answer
959 views

Molarity of pure water [closed]

The molarity of pure water is 55.5 M at which temprature is obtained this value? Further, you will come across that 1000 mL = 1000 g (for water only, but at which temprature?)
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2answers
330 views

Is osmosis really a special case of diffusion across a semipermeable membrane?

A general idea we have about osmosis is that it is the movement of solvent particles through a semi permeable membrane from a region of high concentration to a region of low concentration. This seems ...
2
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1answer
207 views

Freezing point of solution

It's stated in my textbook that at the freezing point, the vapour pressure of the solid phase equals the vapour pressure of the liquid phase. In a mixture, since the vapour pressure of the solution is ...
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2answers
4k views

Relation between size of ion and hydration energy [closed]

Suppose I take 1 tablespoon of an ionic crystal and put it in excess water. We know that shall the hydration energy of the crystal be more than the lattice energy, the crystal will separate in ions ...
2
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1answer
419 views

How to find the concentration of barium ions in a mixture of barium sulfate and barium thiosulfate?

I have a hard time with selective precipitation problem. A mixture of $\ce{BaSO4}$ and $\ce{BaS2O3}$ is shaken with pure water until a saturated solution is formed. Both solids remain in excess. ...
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1answer
432 views

Is vapour pressure a surface phenomenon?

As a fact, I know that vapour pressure doesn't depend on surface area. Does this imply it is not a surface phenomenon also? It shouldn't be as then it would depend on surface area of molecules and ...
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2answers
79 views

How do you get contents of large flask into a smaller separatory funnel?

Separatory flasks that I use have a ground glass joint, but it is not clear how that joint is to be used. Videos I have seen just show people pouring stuff into the throat of the funnel. Normally the ...
2
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1answer
557 views

Why do Cu⁺ ions spontaneously form copper metal and Cu²⁺ ions in solution?

The standard electrode potentials for three reactions involving copper and copper ions are: $$ \begin{align} \ce{Cu^2+(aq) + e- &-> Cu+(aq)} &\quad E &= \pu{+0.15 V} \\ \ce{Cu^2+(...
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0answers
466 views

Henry's law p = kx vs m = kp

What exactly is the difference between the following equations? $$p = kx \qquad\text{and}\qquad m = kp$$ Is the $k$ in both same, because I have seen same $k$ in textbooks for both equations?
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1answer
105 views

Difference of Ascorbic acid dissolved or precipitated in Glycerol?

Difference of Ascorbic acid (AA) dissolved or precipitated in Glycerol? Referring to pat US20110008445A1 Solution 1 At 25C, AA was dissolved in glycerol and alcohol (subsequently removed by ...
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1answer
565 views

Why is the entropy of solidifying solution higher than that of a pure solvent?

According to a source, Solutions have a greater entropy than pure liquids as the particles in a solution are more separated and solvent molecules separate the solute particles. If the number of ...
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1answer
49 views

Neutralisation Reaction Confusion

What will happen when $\pu{1 mol}$ of $\ce{H2SO4}$ reacts with $\pu{1 mol}$ of $\ce{NaOH}$? Will $\pu{1 mol}$ each of $\ce{NaHSO4}$ and water be formed? Or will $\pu{0.5 mol}$ of $\ce{H2SO4}$ will ...
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2answers
52 views

Heating 2% solution to get 4% solution

I have a 2% solution of Zinc sulfate in water (in heptahydrate form) that I want to turn into 4% solution instead of having to buy 4% solution separately. Would heating it to 100 degrees Celsius and ...
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1answer
1k views

Methyl Orange Indicator-Reason for small amount of NaOH [closed]

I used methyl orange as my indicator to titrate a weak acid: At first, I added 3 drops of methyl orange to a solution of the weak acid, $\ce{CH3COOH}$, and the solution turned red. Then, after adding ...
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0answers
111 views

while using Henry's law does it matter if the solvent is volatile or not?

I am studying about binary solutions (with liquid solvents) and came across Henry's law. This is how it's stated in my textbook: Henry's law states that at a constant temperature the solubility of ...
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0answers
30 views

How addition of a soluble salt affects equilibrium involving precipitation with a base sharing the same cation?

I have the following reaction at equilibrium: $$\ce{Ba(NO3)2(aq) + KOH(aq) <=> Ba(OH)2(s) + 2 KNO3(aq)}$$ Will there be a change in the equilibrium if the salt $\ce{KCl}$ is added? Will the ...
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1answer
7k views

Is calcium chloride an acidic or basic salt?

What I reason: Calcium chloride is the salt of hydrochloric acid and calcium hydroxide. Calcium hydroxide is usually not considered a strong base, and I believe this is because of it's low solubility. ...
5
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2answers
1k views

What happens if you mix two insoluble liquids but with the same density? [closed]

Would it make two separate phases? or would it make something like and emulsion?
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1answer
109 views

Adjustment of calcium, magnesium and alkalinity in drinking water?

It's been a long time since I did any molar chemistry in school and despite doing a lot of reading on the subject this week, I am making a mess of some basic calculations. I hope that someone who ...
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0answers
426 views

Trichloroacetic acid aqueous solution

I have bought some anhydride of trichloroacetic acid (TCA) and would like to prepare an acidic solution. My problem is, that I don't know how much "powder" to mix with how much water to produce an x% ...
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2answers
489 views

Does the amount of solute affect rate of solvation?

I know that in order to increase the rate of solvation, you need to increase how often solute and solvent particles come into contact. You can do it by: agitating the mixture increasing the surface ...
2
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2answers
632 views

Thickening and/or slowing evaporation of IPA-based ink

The conundrum I have a security printing ink that I make by adding an IR-absorbing dye to a 50/50 mix of Isopropyl Alcohol and distilled water. The ink solution is pale green but dries virtually ...
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2answers
265 views

Scientific Reason for Salt Solution Gaining Volume

A little background to this question: my mom placed a glass with salt and enough water to just cover the salt in a room to "absorb negative energy" out of the room at her office. It obviously "worked"....
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1answer
580 views

What is the minimum operating temperature of chemical hand warmers?

I have been looking at chemical hand warmers such as Hot Hands, Grabber and HotSnapZ. Unfortunately, I cannot find a minimum operating temperature for these types of devices. Logic tells us that they ...
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1answer
2k views

Calculate pH at equivalence point [closed]

Calculate the pH at the equivalence point of a titration of 62 mL of 0.1 M $\ce{CH_3NH_2}$ with 0.20 M HCl. The $\ce{K_b}=4.4\cdot10^{-4}$. At the equivalence point, the moles of CH3NH2 equals the ...
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0answers
465 views

Will hydrogen chloride dissolved in ethanol react with magnesium?

Magnesium will react with aqueous HCl to form magnesium chloride and hydrogen gas. Simple. But I've just read in my textbook that HCl in a solution of ethanol no reaction will take place. There is no ...
2
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1answer
865 views

How to prepare a Gaussian input file for a binary solvent?

The UV absorption energy spectrum of a molecule has been recorded experimentally using binary solvent (DMSO:Water=9:1 v/v). I am trying to calculate the absorption energy of the same molecule using ...
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0answers
374 views

Can a solute be physically filtered out of a solvent?

Suppose that I have a substance dissolved in water. I then pour the solution into a filter. The filter's pores are large enough to allow the passage of water, but not the passage of the substance. In ...
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0answers
67 views

Freezing point lowering for a mixture of many liquids

I have been taught that if I have a solute of molality $m$ mixed with a liquid, the freezing point in lowered by an amount $K_\mathrm{f}\cdot m$ where $K_\mathrm{f}$ is the molal freezing depression ...
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1answer
163 views

How to keep raspberry ketone from forming crystals again after dissolving in alcohol?

I dissolved raspberry ketone 700 mg in 10 ml of 99% isopropyl alcohol. The solubility according to pub chem is 1 g/ml. After dissolving, I added room temperature water to bring the final volume to 70 ...
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1answer
529 views

How dependent is the molal depression constant on the nature of solute?

I've been reading about the molal depression constant (freezing point depression constant) for binary solutions in class. I encountered a problem (see below) in which the constant $K_f$ was to be ...
11
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1answer
986 views

Is there a name for this algorithm to calculate the concentration of a mixture of two solutions containing the same solute?

There is an algorithm called "Mischungskreuz" (German for "x of mixing") that is sometimes taught as a shortcut to figure out the following problem: You have two solutions that ...
20
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2answers
1k views

Can a stoichiometric mixture of oxygen and methane exist as a liquid at standard pressure and some (low) temperature?

This answer to the question Pre-mixing cryogenic fuels and using only one fuel tank written by a non-chemist (me) begins with: At STP: LOX's boiling point is 90.19 K Methane's freezing point is 90....
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1answer
53 views

How to take a sample of a hot salt solution without it precipitating in the cooler glassware due to the difference in solubilities at different temps?

I'm doing an investigation to see the effect of temperature on the solubility product of strontium hydroxide. I made a supersaturated solution left in the oven overnight at 85°C for equilibrium to be ...
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0answers
299 views

Does the mole fraction of a solution change with Vant Hoff factor?

I reason that as mole fraction is a measure of colligative properties, increase in the Vant Hoff factor ( and hence increase in the value of colligative properties) should also leave a mark on the ...
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1answer
85 views

Reactions between Ca(OH)2 and CO2, and Sr(OH)2 and CO2

So I'm doing an investigation, and it involves using supersaturated solutions of Ca(OH)2 and of Sr(OH)2. I notice that there's always a flaky precipitate formed on top. I need to know about the ...
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4answers
2k 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 ...
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0answers
50 views

Is the analyte included in the ionic strength equation?

I don't quite understand the calculation for ionic strength of a solution. The formula includes the concentration and charges of the ions in solution, however, is the analyte (whatever we're trying to ...
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2answers
2k views

Volume change in positive deviation from Raoult's Law

Let us take a mixture of ethanol and acetone as an example. When ethanol is mixed with acetone, the hydrogen bonding between ethanol molecules gets disturbed as actone molecules get in between the ...
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1answer
349 views

How do I make a solution of spinach to titrate with pottasium permanganate? [closed]

My teacher said something about straining it but I didnt quite get it
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0answers
55 views

Separating NiCl2 and CoCl2

My undergraduate lab is currently doing a project in which we have to separate inorganic compounds from organic compounds, identify each compound, and quantify how much of each compound there is. We'...
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1answer
1k views

Ionic factor of glucose? [closed]

I am trying to find the $K_\mathrm{b}$ for 50 g of glucose dissolved in 1 kg of ethanol, given the change in boiling point is $\pu{2.2 °C}$. The molality is therefore 0.278. But what is the ionic ...
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3answers
1k views

An aqueous solution of NaCl has a mole fraction of 0.21. What is the mass of NaCl dissolved in 100.0 mL of solution? [closed]

Work mole fraction of NaCl = 0.21/0.21+0.79 If there is 1 mol of total solution, there will be 0.21 mol NaCl and 0.79 mol H2O 0.21 mol NaCl = 12.27 g 0.79 mol H2O = 14.23 g this would yield a ...
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1answer
89 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 $$D = \frac{C_\mathrm{A}(\text{ext})}{C_\mathrm{A}(\text{orig})}$$ ...
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1answer
447 views

How to measure the electrical conductivity of a substance? [closed]

Suppose you are given these substances: $\ce{NaOH(aq)}$ $\ce{HCl(aq) }$ $\ce{C6H12O6(aq) }$ $\ce{NH3(l)}$ Are there rules to figure out how conductive each compound is? Is it based on ...
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3answers
281 views

Solubility of solids in liquids

How does crystallisation happen and why? I have been told that when a solid is dissolved in a liquid solvent, an equilibrium is set up between processes of dissolution and crystallisation. But if ...
2
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1answer
267 views

Why zinc sulphate solubility is higher in ethylene glycol than water?

I'm trying to find saturation point for dissolved zinc sulphate in water and ethylene glycol. Based on my knowledge, water is more polar than ethylene glycol as reflected in its higher dielectric ...
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2answers
107 views

Wouldn't adding a proton acceptor still make a solution just as acidic?

Say if you add NH3 to a solution, and it accepts a proton, it still becomes NH4+ in a solution, which is also acidic. A base should decrease the hydrogen ion concentration in a solution, but how does ...
5
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2answers
528 views

Decrease in temperature of an aqueous salt solution decreases conductivity

Why does the conductivity of a water solution drop as the temperature decreases? How are these two related?

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