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
403 views

Does removing solution affect a supersaturated solution

Given a mixture of: a saturated solution of a solute in a solvent together with excess of the solute compound as crystalline material. If one were to change the bulk composition of the mixture by ...
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1answer
15k views

Why is M1*V1 = M2*V2 only used for diluting solutions?

Why is $M_1V_1 = M_2V_2$ only used for diluting solutions? Why can it not be used to figure out how many moles to add to make a solution more dilute?
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1answer
71 views

What is the interaction between dissolved ions of opposite valence in a solution at rest?

NaCl is dissolved in water. Ions sodium and chloride are sufficiently free from each other so that they may occupy different regions of the solution after an active transport process through a ...
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1answer
738 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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1answer
52 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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1answer
1k views

How to determine the proton concentration in the following solution in mol/L? [closed]

A $\pu{0.8L}$ solution contains $\pu{0.60 g }\ce{ NaOH}$ in water. Then the above question follows. It's been a long time that I made some chemistry exercises. Now I'm stuck with a couple of ...
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1answer
406 views

USNCO Question - Determining solute using spectrophotometer

Below is a question from the 2017 USNCO: The concentration of which approximately 0.01M solution could be most accurately determined by a visible spectrophotometer (or colorimeter)? (A) $\ce{Mn(NO3)...
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1answer
40k views

What is the relation between molarity and molality? [closed]

Is the following equation correct: $$m = \frac{1000 \times M}{M \times M_b - 1000 \times d},$$ where $M$ - molarity, $m$ - molality, $d$ -density of solution, $M_b$ - molar mass of solute?
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1answer
6k views

Does glycerin promote bacterial growth the same as water?

A sodium chloride + water solution draws the water out from bacteria through the process of osmosis. Would a sodium chloride + glycerin solution have the same antibacterial effect? If I understand ...
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1answer
223 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 ...
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1answer
386 views

What is the concept behind the calculations for the dilution of solutions?

I'm interested in the concept behind this computation and was wondering if anyone could give me some pointers or hints. I've prepared $0.28~\mathrm{L}$ solution of $0.8500~\mathrm{M}$ of $\ce{Al(NO3)3}...
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1answer
1k views

How to find the mass of a solute given a mass fraction? [closed]

How many grams of $\ce{CuSO4 * 5 H2O}$ are needed to prepare a $20\%$ (w/w%) solution of $\ce{CuSO4}$?
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1answer
3k views

White of an egg

What happens when you dissolve white of an egg in water? Firstly, what's white of an egg? Is it the white part? Or implies whole of an egg? I couldn't relate much of it with colloids, either.
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1answer
5k views

Concentration uncertainty due to volume measurement with cylinder

(All volumes were measured using a measuring cylinder which has a $\pm\pu{0.5 cm3}$ uncertainty) You have a $\pu{50 cm3}$ of $\pu{0.5 M}$ solution to begin with You then make a $\pu{0.4 M}$ ...
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1answer
13k views

What is the difference between IPA and Ethanol in terms of solubility?

I have read an article online that says that ethanol could be used in a solvent extraction of two solids, but it also says that isopropyl alcohol could also be used, but must be used in higher ...
2
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1answer
65 views

What is the mechanism of endothermic dissolution?

My real question is in fact "How can dissolution happen if it's endothermic?" However, there have been many questions regarding this exact topic and the answers about Gibbs free energy ...
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1answer
299 views

Methods to increase the speed of dissolving potassium sulfate in water apart from heating, grinding or shaking

I bought potassium sulfate to be used as a fertilizer. The fertilizer comes in the form of small pebbles 1-2mm in diameter. Wikipedia states that the solubility is around 111g/liter at 20°C. I ...
2
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1answer
266 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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1answer
2k views

How do Invert Sugars deter crystallization in Sucrose solutions?

Invert Sugars, by themselves, are notorious for their reputation to crystallize fast (think honey), but their addition to solutions of Sucrose (think simple syrup) deters the crystallization process. ...
2
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1answer
213 views

Recovering iodine from activated carbon

I have a sample of an iodine solution that has been dyed brown to mask the amount of iodine within. I have added activated carbon to 100 mL of the sample and mixed for 3 hours to remove the iodine ...
2
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2answers
140 views

Solubility of salts

A saturated solution is prepared at 70 °C containing $\pu{32.0 g}~ \ce{CuSO4.5H2O}$ per 100 g solution. A 335 g sample of this solution is then cool to 0 °C so that $\ce{CuSO4.5H2O}$ crystallises out....
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1answer
915 views

With a partition coefficient how do you decide which solute concentration is the numerator?

Kpc = [X(in solvent A)]/[X(in solvent B)] I realise that Kpc is actuallly a ratio but when you need the numerical value it has to be treated as a fraction. When it has to be treated as a fraction ...
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1answer
1k views

Melting point of ocean salt: eutectic?

I'm interested in the melting point of ocean salt. While sodium chloride has a melting point of 801 °C, ocean salt contains 15 % other ions, mainly sulphate, magnesium, calcium and potassium (the ...
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1answer
1k views

How to calculate the depression in freezing point of a solution in which there are multiple solutes being added?

In just about every problem I've encountered earlier, all such questions describe the process for calculating the depression in freezing point for a solution wherein there is only one solute. However, ...
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1answer
161 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 ...
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1answer
9k 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 ...
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2answers
437 views

How to determine the composition for a sucrose/ zinc nitrate solution from its freezing point?

A $4~\mathrm{g}$ mixture of sucrose ($\ce{C12H22O11}$) and zinc nitrate ($\ce{Zn(NO3)2}$) is dissolved in $150~\mathrm{g}$ of water. If the resulting solution freezes at $-0.768~^\circ\mathrm{C}$, ...
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3answers
36k views

How is Langmuir adsorption isotherm different from Freundlich's?

I see no difference between the two. Both say that the degree of adsorption reaches a limiting value at high pressures and at very low pressures degree of adsorption is directly proportional to the ...
2
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2answers
86 views

How do you achieve phase separation of a methanol / chloroform solution?

If I'm washing a methanol solution with chloroform, can I just add water in a 1:1 mixture with the methanol and expect it to break? Do I need to do anything else to cause the aqueous phase to separate ...
2
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1answer
218 views

Why lowering of vapour pressure is not a colligative property?

In my textbook, it is written that lowering of vapour pressure is not a colligative property but relative lowering of vapour pressure is a colligative property. But why is that? There is literally no ...
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1answer
389 views

Universal symbols for molar mass, molarity, and molality

This is a really basic (perhaps trivial) question, but I just want to confirm: What are the SI symbols for molar mass, molarity, and molality? For molality and molarity, there is a difference, but I’...
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1answer
367 views

Effect of impurities on Enthalpy of vapourization

How does the Enthalpy of vapourization change when impurities are added? I know that the boiling point of a substance increases on addition of impurities, but how does the Enthalpy of vapourization ...
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1answer
526 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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2answers
716 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 ...
2
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1answer
669 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 ...
2
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1answer
55 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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3answers
434 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
302 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 ...
2
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1answer
2k views

Equation to find specific gravity (or density) from a solution of sugar and water

Is there an equation or simple way to calculate the final density of a solution made from x grams of sugar and y liters of water? And would it work in reverse? if we have y liters of water at z ...
2
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1answer
148 views

Is volume expansion possible upon dissolution of solute?

I am aware that there is volume reduction upon dissolution of ionic solutes, due to the formation of hydrated spheres of aqueous ions where water molecules aggregate around the solute ions. But ...
2
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1answer
229 views

What is the molecular mechanism behind oncotic pressure?

I can't wrap my head around the idea of oncotic pressure and osmolarity, logically. I imagine a blood vessel. It is filled with proteins, like a ton of proteins and solutes. So this means, according ...
2
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1answer
346 views

Does the rate of movement of ions in a salt bridge affect the total voltage produced by a Galvanic cell?

I was thinking that different salts used in a salt bridge in a voltaic cell may have different rates of flow of ions in them (perhaps ionic radius or some other property affects the rate?) I was ...
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1answer
82 views

What solutes will give the largest reduction in volume when dissolved in water

This question is inspired by another question. If you take some common salt (NaCl) and some water and mix them, then the volume of the solution is less than the volume of the constituents. I did ...
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1answer
3k 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 ...
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1answer
1k 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 ...
2
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1answer
154 views

Sugar dissolution test

Is there a way to detect whether sugar is completely dissolved in a cup of water other than looking at the bottom of the cup? I was wondering if there is a test or something that can be carried out ...
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1answer
457 views

Mixing Different Solutions with Different Wavelengths to Get Different Colors?

I recently was told that the reason you can mix colors (blue and yellow make green because wavelengths 605nm + 450nm = green) was based on wavelength (which seems very obvious when you think about it ...
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1answer
1k views

High/low density water solution values

I would like to know what min and max values of densities are achievable with water solutions. There are some conditions: 1. Normal or close to normal temperature; 2. Non-radioactive solutions/...
2
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2answers
157 views

How do I find a concentration from a sample tested on a spectrophotometer?

I have an assignment to calculate the concentration from a sample. The assignment is: You have 100 µL of RNA. You take 10 µL from the sample and put it in 990 µL of water in the cuvette. The OD is 0....
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1answer
85 views

Max Ionization Extent

How is this formula derived? What does it mean; what is the use of this formula? I know that at infinite dilution, ionization extent should be very high because of Le Chatlier's principle. But I'm ...

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