14 votes
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Why exactly does precipitation occur?

Short story Maybe it will help to think first about a ridiculous case. Say you have a large hydrophilic solid, and a small drop of water is added on top. We would not expect the entire solid to ...
Linear Christmas's user avatar
14 votes
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Are precipitations exothermic and/or endothermic?

No, absolutely not. Precipitation reactions can be either endothermic and exothermic. Table 1. Thermodynamic data of precipitation for some salts \begin{array}{cccccc} \hline \text{Salt} & \Delta ...
William R. Ebenezer's user avatar
11 votes

What is the simplest way to create a precipitation reaction at home?

Here's one easy way : Make a solution of salt ($\ce{NaCl}$) in water, and another solution of Silver Nitrate ($\ce{AgNO_3}$), which you can buy easily) in water. Upon mixing the two, $\ce{AgCl}$ (...
Chemobot's user avatar
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10 votes
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How do Precipitation Reactions behave in the Absence of Gravity?

In gravityless environment, all directions are equivalent save the very vicinity of the surface(*), where just few water molecules are toward the surface. Therefore, in the bulk volume, the ...
Poutnik's user avatar
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8 votes

Why exactly does precipitation occur?

Although you ask specifically about forming precipitates your question is also about the solubility of one substance in another. The simplest answer as to why precipitates form is because the free ...
porphyrin's user avatar
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8 votes
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How do I separate an Indium-Gallium alloy into Indium and Gallium?

The Gallium-Indium binary system is assessed by Bridget C. Rugg and Tim G. Chart in Calphad 14(2) 115-123 (1990). It is a very simple system, exhibiting essentially no solubility of In in Ga, and ...
Jon Custer's user avatar
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7 votes
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What reactions occur when mixing copper sulfate and sodium hydroxide?

As noted in your question and in one of the comments, copper forms many different complexes having a variety of colors from red to green to blue to black and probably more. Of course the situation ...
airhuff's user avatar
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7 votes

Finding sulfate contamination in crystallized silver nitrate

Barium nitrate has a water solubility of $\pu{10.5g/100mL}$ at $\pu{25^oC}$. It isn't specified in the question what concentration of sulfate you suspect might be present, but given that you are ...
airhuff's user avatar
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7 votes
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Finding sulfate contamination in crystallized silver nitrate

Your choices are restrained as the precipitation of $\ce{SO4^{2-}}$ in $\ce{BaSO4}$ is the classical way to quantify the former and an electrochemical determination (in aqueous solution) is not ...
Buttonwood's user avatar
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7 votes

Mathematical explanation of blank titration in Mohr method for argentometry

$\ce{AgCl}$ ppts before $\ce{Ag2CrO4}$. But in order to visually detect the $\ce{Ag2CrO4}$ you must add a slight excess of $\ce{Ag^+}$. Hence you use a "blank" with no $\ce{Cl^-}$ to account for the ...
MaxW's user avatar
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7 votes
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Why is only the carbonate anion used to precipitate Barium?

Actually, the textbook should remove this question. You should discuss this with your teacher. It will be a service to future students. The heavier elements of group II elements form insoluble ...
AChem's user avatar
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6 votes

How to remove sulfuric acid from sample

Sulfuric acid is an excellent dessicant and is also very non-volatile itself (it boils at 337 °C). In other words it would likely still have been there in yet another month. Your instructor ...
airhuff's user avatar
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6 votes
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Precipitation of CaCl2 and FeCl3 in Na2CO3

This must have been a very good question for a geochemist. They'd give you a complete answer with details of why $\ce{Fe2(CO3)3}$ does not but $\ce{Fe2O3}$ exist in our surrounding. Yet, I would like ...
Mathew Mahindaratne's user avatar
6 votes

Can precipitation occur in states of matter other than liquids?

As stated in my previous answer on precipitation, formation of precipitates in supercritical is a common issue. Ask those who do sub/supercritical fluid chromatography. Sometimes you inject a methanol ...
AChem's user avatar
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6 votes
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Magnesium vs calcium vs barium ions from these 3 tests

The unfortunate thing is that salts of these ions are white and can't be differentiated by just looking. But you can take solubility to your advantage. The solubility of the sulfates of alkaline earth ...
Nilay Ghosh's user avatar
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5 votes
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Aluminium sulphate solubility as function of the pH

The lack of continuity for the curve indicates that the concentration of $\ce{Al2(SO4)3}$ was below the detection limit of the analytical technique being used to measure the concentration of $\ce{Al2(...
MaxW's user avatar
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5 votes
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Are precipitation and crystallization both analogous between Chemistry and Meteorology?

In chemistry, on Earth in gravity, if a material from solution conformally, over all surfaces vertical and horizontal (e.g. the sides as well as the bottom of a container) is that still sometimes ...
AChem's user avatar
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5 votes

Can precipitation occur in states of matter other than liquids?

In "chemistry", we generally have a good idea of what we mean by precipitation: something falls down out of a liquid and we filter it off. Then we extend the definition to meteorology for ...
James Gaidis's user avatar
5 votes
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Doubt on the process to determine the amount of precipitate of a salt, product of a reaction between two solutions

Here is a summary of the steps I would use: Determine the concentration of silver and chloride ions in the mixture, assuming that no silver chloride precipitates. Compare the solubility product to ...
Karsten's user avatar
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5 votes

Magnesium vs calcium vs barium ions from these 3 tests

Magnesium sulfate $\ce{MgSO4}$ is soluble in water. So when adding some dilute sulphuric acid $\ce{H2SO4}$ to the solution of magnesium sulphate, no precipitate should occur. It should occur with ...
Maurice's user avatar
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5 votes
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Why are iodine precipitates yellow?

There is certainly some variance between different cases, but a major factor is that bonds to iodine are weaker than bonds to lighter halogens. The large size of the iodine atom decreases ...
Oscar Lanzi's user avatar
4 votes

How can I make a black precipitate without a sulfide?

Hint: Manganese dioxide is pretty black. Look up potassium permanganate and note its reactions especially the reduction in neutral solutions.
Oscar Lanzi's user avatar
4 votes

When our hard water is boiled, it leaves a blue-green residue in our kettle.

If your building's water pipes are made of copper, that could explain the blue-green coloration. Hopefully the inside of your pipe doesn't look like this, though:
IT Tsoi's user avatar
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4 votes

What reactions occur when mixing copper sulfate and sodium hydroxide?

Yes, as noted by @airhuff, there is not one but two reactions involving, one is formation of greenish-pale blue copper sulfate, $\ce{CuSO4}$ and other one is formation of black-brown copper(II) oxide $...
Nilay Ghosh's user avatar
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4 votes

Why exactly does precipitation occur?

Solubility is the concentration at which the chemical potentials of the solute in itself and in the solution are equal. The chemical potential of a substance is the change in Gibbs free energy upon ...
gsurfer04's user avatar
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4 votes
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How much calcium hydroxide will precipitate after addition of sodium hydroxide into saturated calcium hydroxide solution?

A less analytic aproach: Initial concentrations: $K_{\mathrm{sp}}=\ce{[Ca^{2+}][OH^-]^2}=x\cdot (2x)^2=8\cdot10^{-6}$ $\ce{[Ca^{2+}]=0.0126}$ M; $\ce{[OH^-]=0.0252}$ M. Now 0.1 mol NaOH is added. ...
Raoul Kessels's user avatar
4 votes
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Hydrolysis of transition metals' halides?

$\ce{MCl_n(aq)} + n\ \ce{H2O(l)} \rightarrow \ce{M(OH)n(s)} + n\ \ce{HCl(aq)}$ does tend to go to the right. "Basically insoluble" is not quantitative enough to generalize. If the hydroxide is very ...
James Gaidis's user avatar
4 votes

CaSO4 precipitate in mixture of Na2SO4 and CaCl2 solutions

When all of the $\ce{CaSO4}$ is dissolved completely, all the calcium ions originate from the $\pu{100 mL} \; \ce{CaCl2}$ solution, so it is easy to determine the amount: $$n_\ce{Ca^2+} = \pu{100 mL \...
Karsten's user avatar
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