Questions tagged [precipitation]

For questions related to the chemical reactions and processes that result in a chemical reaching its solid phase.

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26
votes
1answer
775 views

Why is it that every snowflake is unique?

It's pretty hard to believe in around 4.5 billion years of this planet's existence, no snowflake pattern was repeated, and that's not including potential earth-like planets. Is there a proof to the ...
18
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3answers
2k views

How do Precipitation Reactions behave in the Absence of Gravity?

How do precipitation reactions behave in the absence of gravity, say on the International Space Station (ISS)? I have seen water taking the shape of a sphere and not that of the container in space due ...
12
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3answers
4k views

Why exactly does precipitation occur?

In a solution, we have ions floating around but when we have a precipitate, they're arranged as they would be in a solid. This conversion should cause a decrement in the entropy of the system and ...
12
votes
1answer
200 views

In the wet medium of an ocean, how does a hard shell form?

In general, if you were to try make something hard in a liquid medium (especially water) it is quite difficult to make the material solid. Things such as mollusks though, have no problem generating ...
10
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3answers
3k views

Experimental calculation of solubility product constant

In order to calculate the $K_\mathrm{sp}$ of lead(II) iodide, I mixed $\pu{6.0 mL}$ of $\pu{0.01 M}$ $\ce{Pb(NO3)2}$, $\pu{6.0 mL}$ of $\pu{0.02 M}$ $\ce{KI}$, and $\pu{8.0 mL}$ of water, and a ...
10
votes
1answer
449 views

Reaction of barium peroxide forming barium carbonate

I stumbled across this reaction: $$\ce{BaO2 + H2CO3 -> BaCO3 + H2O2}$$ This reaction seems quite similar to the variant with sulfuric acid $$\ce{BaO2 + H2SO4 -> BaSO4 + H2O2}$$ which is well ...
9
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7answers
22k views

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

What is the easiest way to create a precipitation reaction at home, preferably with easily retrievable chemicals? I need this because I'm making a video for my film education.
8
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4answers
135k views

Reaction of silver nitrate and hydrochloric acid

Consider the reaction of $\ce{AgNO3}$ and $\ce{HCl}$. I read that silver chloride would be formed. But $\ce{H} > \ce{Ag}$ in reactivity, then how could $\ce{Ag}$ displace $\ce{H}$ from $\ce{HCl}$ ? ...
8
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2answers
2k views

Why do carbonates, oxides, and pure metals precipitate before metal sulfides?

Water tends to leach metals near the surface and deposit them deeper through precipitation in two layers. The upper layer is usually made of metal carbonates, oxides, and occasionally pure or native ...
8
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0answers
281 views

DIY hand sanitiser solution forms spongy substance

I am trying to make my own hand sanitiser since it’s sold out everywhere. The formula I use is 1 part aloe vera gel in 2 parts 100% isopropyl alcohol. The problem is when mixing the two, the solution ...
7
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3answers
716 views

Can precipitation occur in states of matter other than liquids?

This answer to Are precipitation and crystallization both analogous between chemistry and meteorology? discusses the history and use of the term "precipitation" in chemistry. From what I ...
7
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1answer
10k views

What is the chemical composition of Turnbull's blue?

I was studying qualitative analysis from this book and I found some tests for testing the presence of the cation $\ce{Fe^{++}}$. There was a test in which we add $\ce{K4[Fe(CN)6]}$ solution to a ...
7
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3answers
2k views

How much calcium hydroxide will precipitate after addition of sodium hydroxide into saturated calcium hydroxide solution?

Below was question 34 in the USNCO 2017 exam: If $\pu{0.10 mol}$ of solid $\ce{NaOH}$ is added to $\pu{1.00 L}$ of a saturated solution of $\ce{Ca(OH)2}$ $(K_\mathrm{sp} = \pu{8.0 \times 10^-6})$, ...
7
votes
3answers
17k views

Why does silver sulfate not precipitate in this double displacement reaction?

Aqueous silver nitrate is mixed with aqueous sodium sulfate. We were asked to perform this reaction in lab in my chemistry class, and we did not observe a precipitant being formed. However, the ...
6
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2answers
20k views

What reactions occur when mixing copper sulfate and sodium hydroxide?

I tried reacting copper sulfate with sodium hydroxide to get copper hydroxide, which should precipitate, according to the following equation: $$\ce{2NaOH + CuSO4 -> Cu(OH)2(s) + Na2SO4}$$ I ...
6
votes
4answers
15k views

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

The inside of our kettle is lined in a blue-green deposit. Our water is very hard, but what minerals could cause the coloration?
6
votes
1answer
534 views

What chemical reaction can cause this blue-ish deposit?

Recently I noticed that some of our glasses and cutlery had developed a blue-ish deposit as you can see for the two sets of spoons below. For each set the spoon on the left has the blue-ish deposit ...
6
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1answer
2k views

Saturation of multiple solutes

Can a liquid which is saturated with a single solute, dissolve a different solute, or is saturation a universal thing? I ask because I’ve seen that different solutes have different points (amounts) at ...
6
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2answers
868 views

How to find the mass of dissolved AgCl when placed in a solution of NaCl?

I think the following problem in my textbook is malformed: Solid $\ce{AgCl}$ is placed in $1\,\mathrm{L}$ of $0.55\,\mathrm{M}$ $\ce{NaCl}$. Find the mass of $\ce{AgCl}$ which dissolves. I know ...
6
votes
1answer
938 views

How can I make a black precipitate without a sulfide?

I'm supposed to make a black precipitate using only the following chemicals: copper sulfate(II), lead nitrate, acetic acid, barium chloride, sodium hydroxide, copper(II) carbonate, methanol, potassium ...
6
votes
1answer
143 views

Determine the concentration of hydrogen cations to prevent precipitation of monocalcium phosphate?

Determine the $\ce{[H+]}$ needed to just prevent precipitation by $\ce{H2PO4-}$ in a $\pu{0.25 M}$ $\ce{H3PO4}$ solution that has $\ce{[Ca^2+]} = \pu{0.15 M}$. The $K_\mathrm{a1}$ of $\ce{H3PO4}$ is ...
6
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3answers
18k views

How does boiling water affect its hardness?

Does boiling water reduce its hardness, or on the contrary, increase it? It seems there are ambivalent phenomena at play here: boiling will evaporate pure water, thus increasing the concentration of ...
5
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1answer
963 views

Mathematical explanation of blank titration in Mohr method for argentometry

In my book it is written that in order to minimize systematic error in Mohr method for argentometry it is a common procedure to conduct a blank titration with $ \mathrm{Ag^+} $ against a $\mathrm{CrO_{...
5
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2answers
567 views

Aluminium sulphate solubility as function of the pH

earlier I asked about how to know the aluminium sulfate solubility as function of the ph (see the previous question here). I found this diagram on the page 57 of Rubin, A. J., & Hayden, P. L. (...
5
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1answer
1k views

Constructing an equation for the precipitation of a salt

I was asked to write a balanced equation, as well as the net ionic equation, for the formation of $\ce{CaCO3}$ by precipitation. The equations should also include state symbols. Unfortunately, I am ...
5
votes
1answer
804 views

Which calcium salt is good enough to make calcium benzoate?

This question is inspired from the following questions: Reaction of citric acid and calcium chloride Precipitation of citric acid by CaCl2 and Ca(OH)2? The answer to the 1st question says that ...
4
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4answers
27k views

Difference between precipitation and crystallisation

What is the main difference between precipitation and crystallization. Is precipitation a chemical change and crystallization a physical change. How can we say that the resulting solute is precipitate ...
4
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2answers
236 views

Finding sulfate contamination in crystallized silver nitrate

What is the best way to check for a small amount of sulfate contamination (if any) in silver nitrate? Usually, I would use dilute barium chloride to precipitate out the resulting insoluble white ...
4
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3answers
1k views

CaSO4 precipitate in mixture of Na2SO4 and CaCl2 solutions

I have been stuck on a chemistry problem for a long time now and if anyone here can help me I would be eternally grateful. 40. Du tillsätter $\pu{100 ml}$ $\pu{0,01 M}$ $\ce{Na2SO4}$-lösning i $\pu{...
4
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2answers
4k views

Method and Tips for Inorganic Qualitative Analysis

In a few weeks time, I will be doing an inorganic qualitative analysis test which is very pressed for time (a majority of people don't finish). The form of the test is most likely going to be that ...
4
votes
1answer
181 views

Why is only the carbonate anion used to precipitate Barium?

Q: Why is the $\ce{CO3^2-}$ anion used to precipitate Barium from $\ce{BaBr2}$ and not another anion, such as $\ce{PO4^3-}$, or $\ce{SO4^2-}$? I am studying high school Chemistry, and the current ...
4
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1answer
7k views

Do all double displacement reactions lead to precipitates?

I know that most of the double displacement reactions form some kind of precipitates as their products. But do all of the double displacement reactions form precipitates? I have searched on this site ...
4
votes
1answer
3k views

How to remove sulfuric acid from sample

I have problem with my experiment. My experiment is acid hydrolysis of ethyl benzoate. The acid that I used is sulfuric acid. My problem is when I get the precipitate (impure benzoic acid) I have to ...
4
votes
1answer
113 views

Why use "molecular equation" to refer to a chemical equation describing a precipitation reaction?

When we describe a precipitation reaction using a chemical equation, we have the choice of either writing the net ionic equation (i.e. leaving out spectator ions) or writing the respective ionic ...
4
votes
1answer
216 views

Why is the test for sodium as dihydrogen antimonate so specific?

I have been attending lectures of salt analysis in my college. We are at group 6 cations or also known as group zero cations, namely $\ce{NH4^+}$, $\ce{K^+}$, $\ce{Na^+}$, $\ce{Mg^2+}$. The lecturer ...
4
votes
1answer
238 views

Is chromate a suitable indicator for the titration of Ag⁺ with Cl⁻?

To titrate $\ce{Cl-}$ with $\ce{Ag+}$ we use chromate $\ce{CrO4^2-}$ as an indicator. The titration reaction is: $$\ce{Ag+ + Cl- <=> AgCl}\tag{R1}$$ $$K_1 = \frac{1}{K_\mathrm{sp}(\ce{AgCl})} =...
4
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2answers
527 views

What's the reddish powder that oozes out of a black rock?

As an artist, some of the work I do involves the use of seashells, sea rocks/stones, etc. I picked up a black rock from shore at one of the beaches here in Florida and it looked somewhat clumpy with ...
4
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1answer
76 views

Co-precipitation particle size

If we are creating a precipitate of (say) Barium Sulfate from a solution of Barium Chloride mixed with Sodium Sulfate, what determines the particle size? I assume one of the factors will be ...
4
votes
1answer
3k views

How to determine which salt will precipitate from a solution containing multiple ions?

I have a solution containing $0.2\:\mathrm{mol}$ of $\ce{Br^-}$ ions and $\ce{SO_4^2-}$ ions each. Now if I add excess $\ce{AgNO3}$ in this solution, what will precipitate? $\ce{Ag2SO4}$ or $\ce{...
4
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3answers
146 views

Does brewing tea with hard water reduce the amount of bioavailable fluorine?

I read that brewed tea contains a relatively large concentration of Fluorine. Fluorine can have negative health effects such as Skeletal Fluorosis. EDIT: I understand some Fluorine is necessary and ...
4
votes
1answer
572 views

Gravimetric analysis of barium or sulfate

Which is a better way to obtain barium sulfate precipitate for gravimetric analysis: by adding $\ce{Ba^2+}$ ions to sulfate ion solution, or the other way round? I think it is better to precipitate ...
4
votes
1answer
134 views

Measurement of Water Clarity

Turbidity is essentially the clarity of water. Turbidity can be measured in many ways such as a turbidimeter, secci disk or a turbidity tube (which incorporates a secci disk at the bottom). If you had ...
3
votes
3answers
895 views

Obtain precipitated iron?

Is it possible to obtain pure, precipitated iron with no oxidation by some chemical process? Alternatively is it possible to electrically purify iron using an anode and cathode?
3
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2answers
8k views

Why are transition metal hydroxides insoluble?

From what I understand, adding $\ce{NaOH}$ to a solution containing transition metal ions gives transition metal hydroxide precipitates. Why is $\ce{NaOH}$ soluble but transition metal hydroxides ...
3
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2answers
4k views

Why did my iron nails not dissolve in hydrochloric acid?

I was trying to dissolve iron metal in HCl to make iron chloride, but ran into some problems. I'll give a brief background of my experiment. I took iron nails and put them in a container filled with ...
3
votes
1answer
128 views

Are precipitation and crystallization both analogous between Chemistry and Meteorology?

A comment under the Space SE question Is there really precipitation on Mars? Does frost count? brings up the use of the term "precipitation" in chemistry and we wonder if precipitation in ...
3
votes
1answer
1k views

Does gold always become gold chloride when dissolved with HCl and an oxidizer and can it always be precipitated with sodium metabisulfate?

I tried to extract gold from computer parts by STRIPPING the gold using $\ce{HCl}$ and $\ce{H2O2}$ by dissolving the copper & nickel underneath but i added FAR too much $\ce{H2O2}$ by a stupid ...
3
votes
2answers
117 views

Why do reusable heat packs have a limited time frame before the reaction becomes irreversible?

I have two "rechargeable" heat packs which from my understanding operate on the phase change $$ CH_3COONa_{(aq)} \rightleftharpoons CH_3COONa_{(s)} + \Delta H.$$ Triggering the ...
3
votes
2answers
75 views

Preparation of Barium Hexaaluminate using co-precipitation reaction mechanism

I am preparing Barium Hexaaluminate (BHA) using $\ce{Ba(NO3)2, Al(NO3)3}$, and $\ce{(NH4)2CO3}$. For $\pu{1 mol}$ of each $\ce{Ba(NO3)2}$ and $\ce{Al(NO3)4}$, I am using $\pu{1.5 mol}$ of $\ce{(NH4)...
3
votes
1answer
62 views

Chemical based Water Purifier

I am currently researching as too which is better for purifying a water sample. I have obviously tried the standard Google search for 'Aluminium Sulphate or Ferric Chloride' and have come up with lots ...