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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Why do salts such as NaCl dissolve?

If we look at solubility of salts in water, we are told that they disassociate, because the positive $\ce{Na}$ ion is attracted to the partially negative oxygen in water and the negative $\ce{Cl}$ is ...
Gerard's user avatar
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19 votes
2 answers
30k views

How does volume contraction in solvent mixing work?

I recall seeing chemistry demonstrations where a significant amount of a solute is dissolved in a solvent and the solution volume barely changes. Questions regarding this: 1) How is this possible? 2)...
docscience's user avatar
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-1 votes
2 answers
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Calculate pH of a mixture of a strong base and acid. Knowing only the pH, wt/v%, and volume of both solution. [closed]

Title explains all. I have been stuck on this for an hour and for some reason cannot understand it. I have tried to do an ICE table but get stuck halfway as I do not know whether I would use the w/v ...
Oliver A.'s user avatar
6 votes
2 answers
30k views

What is an equivalent?

I want to know what is an equivalent and how is it different from equivalent mass. How to calculate and why is it used in chemistry for knowing concentration?
Uzair's user avatar
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50 votes
9 answers
515k views

Why does ice water get colder when salt is added?

It is well known that when you add salt to ice, the ice not only melts but will actually get colder. From chemistry books, I've learned that salt will lower the freezing point of water. But I’m a ...
cspirou's user avatar
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13 votes
2 answers
10k views

Should bromine water be called a solution?

Bromine water is a reagent which is used to test for unsaturation in organic compound. It is $2.8~\%$ bromine in water. In many places, it is refer to as bromine solution. But it is observed that ...
Nilay Ghosh's user avatar
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6 votes
2 answers
1k 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"....
Kendall's user avatar
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21 votes
1 answer
2k views

How to think of solvated electrons?

This excellent answer explains at length what's happening in this fascinating video entitled Liquid Electrons - Periodic Table of Videos. In the screenshot below, the metallic-looking solvated ...
uhoh's user avatar
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19 votes
3 answers
59k views

Why there is no change in water level when salt is added?

Let us say we have one glass of water and after that when we add one or two spoon of salt then we notice that salt dissolves in it but when we measure the water level we found that there is no ...
Shashank's user avatar
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12 votes
5 answers
41k views

Is it possible to separate/remove sugar from common drinks, such as juice?

Is it possible to remove sugar from a drink (for example, juice) using common household equipment?
R S's user avatar
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16 votes
1 answer
1k views

What is happening in this video of solvated electrons donated from sodium in ammonia?

I just saw the Periodic Video Liquid Electrons - Periodic Table of Videos where sodium is added to liquid ammonia. The demonstration shows that even if electrons are solvated, if you have a high ...
uhoh's user avatar
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7 votes
1 answer
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Why do some solid chemicals dissolve better in colder water?

I just discovered that some solid chemicals, such as $\ce{Na2SO4}$, dissolve better in cold water than hot water from here and would like to know if there is any particular reason as to why. Is it ...
user2813274's user avatar
5 votes
3 answers
12k views

Can there be more solvent in a solute?

Something I know that leads to this question: Water dissolved in ethanol. It might sounds weird to say water as a solute. Textbooks always says that solvent is the one present in larger quantity. ...
most venerable sir's user avatar
3 votes
1 answer
5k 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.
shiva22's user avatar
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23 votes
5 answers
6k views

Can gases be "immiscible"?

Anyone know of any examples of gas mixtures that phase separate, analogously to the way immiscible liquids do? They would have to be extremely non-ideal. I might guess one might have to be much ...
ericksonla's user avatar
  • 1,690
20 votes
2 answers
13k views

What causes the lowering of vapour pressure in volatile/nonvolatile solvent mixtures?

"Based on Figure 13.18, you might think that the reason volatile solvent molecules in a solution are less likely to escape to the gas phase, compared to the pure solvent, is that the solute molecules ...
Leponzo's user avatar
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17 votes
2 answers
15k views

What is the reason for the blue color of an ammoniated electron?

I am quoting a line from a book regarding reactivity of alkali metals with liquid ammonia. The blue colour of the solution is due to the ammoniated electron which absorbs energy in the visible region ...
aman's user avatar
  • 391
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 ...
Tyreke Davis's user avatar
14 votes
3 answers
34k 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 ...
Ahmed Fwela's user avatar
11 votes
1 answer
64k views

Does concentration of salt increase or decrease rate of rusting?

I want to know whether increasing the concentration of salt, specifically $\ce{NaCl}$, increases or decreases the rate of rusting. There are conflicting theories that explain opposite outcomes: ...
Tejas Ramdas's user avatar
9 votes
1 answer
3k views

Vapor pressure of immiscible liquids

I have read that vapour pressure of a mixture of two immiscible liquids is $$P=P^0_A + P^0_B$$ where A and B are immiscible liquids. If they are immiscible, they would form separate layers. Thus ...
ABC123's user avatar
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7 votes
1 answer
492 views

Is it possible to have Volume(solution) < Volume(solvent before adding solute)?

I understand the answer to the question "Is it possible to have Volume(solution) < Volume(solvent) + Volume(solute)?" is "yes" -- but it is possible that adding a solute causes the solvent to ...
zacronos's user avatar
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28 votes
5 answers
17k views

Why is water "the universal" solvent?

This is an old question that our textbook tried to answer but worsened the situation. Many things are soluble in water. So many, that studying solutions will always require studying aqueous ones. It ...
M.A.R.'s user avatar
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23 votes
4 answers
18k views

Can other substances be dissolved in a saturated solution?

If I have a liter of water fully saturated with sucrose would it be possible to dissolve something like salt or any other substance in the water? Or when the solution is saturated, is it impossible to ...
Samantha Clark's user avatar
16 votes
2 answers
25k views

Why does like dissolve like?

Polar solvents love polar solutes to be dissolved in it and non polar with non polar. Often said as like dissolves like. Okay, polar loving polar can be understood with help of the facts: same polar ...
Pranjal Rana's user avatar
13 votes
1 answer
2k 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 ...
Karsten's user avatar
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12 votes
3 answers
41k views

How is dissolving a physical change and not a chemical change?

When salt dissolves in water it dissociates and it is no longer in a lattice structure. The electrostatic forces are no longer there and are replaced by water-ion interactions. To me that sounds like ...
la.vie.en.rose's user avatar
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 ...
Renganathan Subramanian's user avatar
9 votes
3 answers
2k views

Where does the Fe(III) ion go?

Iron(II) sulphate solution is added to a test-tube. Following this, potassium manganate solution is added gradually to the test-tube as well. The observation seen is that the green solution turns pink ...
Sara's user avatar
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9 votes
1 answer
6k views

Why does permanent marker writing come off a white board when coated with white board marker?

Why is it that dry erase markers allow permanent markings to come off? Here's a demonstration.
DarkLightA's user avatar
9 votes
3 answers
3k views

Why is there a decrease in the total volume when NaOH dissolves in water?

When a solute is added to a solvent, the volume of the solution should be equal to the sum of the individual volume of the solute and solvent (i.e total volume), right? But why is there a decrease in ...
Yitian Chen's user avatar
9 votes
2 answers
81k views

What is the differences between partial pressure and vapour pressure?

Was looking at Henry's law and Raoult's law constants and there seemto be lots of equations involved. Henry's law involves partial pressure and the latter involves the vapor pressure. Wondering what ...
Uzair's user avatar
  • 555
8 votes
3 answers
980 views

Detailed kinetic explanation for vapor pressure reduction by dissolved solute?

The following problem was asked in JEE Mains 2020 (Sept 2, Shift 1), An open beaker of water in equilibrium with water vapor is in a sealed container. When a few grams of glucose are added to the ...
Rahul Verma's user avatar
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8 votes
2 answers
18k views

Thermodynamics adding salt to water changes the temperature

$5\:\mathrm{g}$ of an unknown salt are dissolved in $325\:\mathrm{g}$ of water. Both the water and the salt are initially the same temperature. The water's temperature falls by $11.4\:\mathrm{^\circ{}...
okarin's user avatar
  • 375
8 votes
2 answers
2k 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 ...
docscience's user avatar
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6 votes
1 answer
21k 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 ...
ShadowWolf's user avatar
6 votes
1 answer
1k views

Phase abbreviations for non-aqueous solutions

When writing a chemical equation, how do you indicate that a chemical is dissolved in a non-aqueous solvent? For example, it would be inappropriate to write X (aq) when X is dissolved in benzene, ...
Sam Lewis's user avatar
5 votes
1 answer
2k views

Raoult's Law and Mole Fraction

Raoult's Law states that the partial vapor pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture....
Tyrion Lannister's user avatar
5 votes
1 answer
15k views

Deviation from Raoult's law because of adhesive and cohesive forces

A solution made of two or more compounds have adhesive and cohesive forces. Cohesive forces are the attractive forces between the same molecules. Adhesive forces are the attractive forces between ...
Rafique's user avatar
  • 1,009
4 votes
1 answer
614 views

Solvated solids

I have a very basic question concerning solvation. If a solid (solute) was dissolved in a liquid (solvent), is the solute still in the solid state? or does it convert into another state of matter when ...
Error404's user avatar
  • 273
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 ...
M.M's user avatar
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3 votes
1 answer
182 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: ...
EJC's user avatar
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3 votes
3 answers
3k 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 ...
DoubtExpert's user avatar
3 votes
1 answer
48k views

Calculating the molar mass of a solute from freezing point

A $\pu{4.305 g}$ sample of a nonelectrolyte is dissolved in $\pu{105 g}$ of water. The solution freezes at $\pu{-1.23^\circ C}$. Calculate the molar mass of the solute. $k_f$ for water is $\pu{1.86 C/...
James's user avatar
  • 31
3 votes
1 answer
3k views

Electrode Potential at Equilibrium

At each electrode-electrolyte interface there is a tendency of metal ions from the solution to deposit on the metal electrode trying to make it positively charged. At the same time, metal atoms of the ...
Tyrion Lannister's user avatar
2 votes
3 answers
2k views

Saturated vs Supersaturated

The way I was told is that a saturated solution contains the maximum amount of solute and a supersaturated solution contains more solute than a solution can hold at a particular temperature. But I was ...
Sarah's user avatar
  • 95
2 votes
1 answer
2k 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^\circ &= \pu{+0.15 V} \\ \ce{Cu^2+(...
Mayuri Vaish's user avatar
1 vote
2 answers
412 views

Does adding solutes to water alter its triple point? [closed]

Does adding solutes to water alter its triple point? If yes, how do we find the new temperature and pressure of this point?
NoLand'sMan's user avatar
1 vote
2 answers
1k views

Freezing Point Depression and Temperature Decrease

I don't have a problem understanding the chemical mechanisms underlying freezing point depression or colligative properties in general, but what I cannot seem to grasp is how if you add salt to ice ...
MattGeo's user avatar
  • 153
0 votes
1 answer
2k views

What if solute and solvent exist in equal quantities?

A solution is made of solute and solvent, like salt in water, however, what if the solute and solvent exist in equal quantities? Which one is the solute and which is the solvent? If one of them is ...
Lailak Al Kahachi's user avatar