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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How to know when dissolution is complete?

In a given solubility equilibrium, I know that if $ Q >K_s$, then the salt will precipitate until $ Q =K_s$. If $ Q <K_s$, however, would the precipitate dissolve until $ Q =K_s$ too?
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1k views

How to determine the minimum pH at which iron(III) hydroxide dissolves completely?

Knowing $K_\mathrm{s} = 6\cdot10^{-38}$ for $\ce{Fe(OH)3}$ in neutral solutions, calculate the minimum pH of an acidic solution in order to completely dissolve $\pu{10 mg}$ of $\ce{Fe(OH)3}$. Data: $V ...
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986 views

How to determine sulfate ions in a solution by precipitation? [closed]

For example I am given an unidentified solution and am told that it may or may not contain sulfate ions. How can I confirm or deny the presence of sulfate in this solution?
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211 views

Fast and complete ways to remove chloride from solution (sub ppb levels)

Main question: We are trying to reduce the chloride concentration in a solution to sub-ppb levels. I have to dissect a fruit fly in this solution so I am interested in removing any chloride that is ...
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2answers
522 views

Common ion effect math problem

The question was: If you are given a $1$ Litre solution of $\ce{CaF_2}$where there is $2.0 \times 10^{-5}$ M $\ce{Ca^{2+}}$. How many mililitres of $0.1$ M $\ce{NaF}$ would you need to precipitate $...
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Triiodide ion gravimetric analysis Reaction Equation

Last week I did a gravimetric analysis from the following reaction. $\ce{AgNO3 + (CH3)4N+I3- -> AgI(s) + (CH3)4N+NO3- + I2}$ The objective was to identify if my reactant was triiodide or ...
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Do we cool the solution to form a precipitate because of lower melting points?

If we have two compounds in aqueous solution, in order to separate one from the other the solution is placed into an ice bath. For example the formation of $\ce{KClO3}$ from a combination of $\ce{...
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1answer
366 views

What is the difference between fractional freezing and fractional crystallization?

More simply put, what is the difference between freezing and precipitation when considering a mixture? Take two scenarios: First a mineral in water. If the temperature of this solution is lowered, ...
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What chemicals could be added to human urine to cause harmful chemicals to precipite out?

What chemicals could be added to human urine to render it drinkable with no harmful side effects? Urine is salty and contains other dissolved solids. Thus, drinking untreated urine would result in ...
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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?
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1answer
676 views

How to calculate the amount of substance of barium sulfate that is precipitated?

Determine the amount (in mol) of barium sulfate that will be precipitated when $200.0~\mathrm{cm^3}$ of $0.450~\mathrm{mol\,dm^{–3}}$ barium nitrate solution is added to an excess of sodium sulfate ...
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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 ...
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1answer
264 views

How to separate benzyl alcohol and meta-cresol

Benzyl alcohol and meta-cresol boiling point's are not so different, the fractional distillation will be very difficult, what can i do for separate this two composites ?
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Precipitation occurred when adding vanilla extract to oak extract. What caused this?

Sorry if this is a very obscure question, but I don't know where to ask it. 120ml of oak extract, made by soaking oak chips in ethanol, was added to a flask. At this point, the solution was very dark ...
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The behaviour of Ag3PO4 in solution

To a $\pu{1L}$ flask, we add $\pu{4.1900 g}$ ($\pu{0.01001 mol}$) of $\ce{Ag3PO4}$, then fill it up with water. Knowing the following constants, we are asked to find the concentration of all species ...
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554 views

Precipitation of citric acid by CaCl2 and Ca(OH)2? [closed]

I need to precipitate citric acid from an aqueous solution in the form of calcium citrate. There are, to my knowledge, two different methods of doing this: using $\ce{CaCl2}$ and which will react ...
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2k 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 ...
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1answer
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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 ...
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Precipitaiton of aragonite

I'm not positive what this questions is asking. The prompt says "Write balanced equations for the following processes. Chemical species should be the dominant ones at the given $\mathrm{pH}$. Show ...
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1answer
245 views

How to decide from the solubility product constants which hydroxide precipitates first?

Salts of $\ce{Fe^3+}$ and $\ce{Al^3+}$ are in a beaker of water. If NaOH is added slowly, what compound would precipitate first? For me, I think it's $\ce{Fe^3+}$ because of its lower $K_\mathrm{sp}$...
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What is the simplest way to create a precipitation reaction at home

Whats 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.
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1answer
990 views

Ion/Counter ion layers in the colloid precipitate of silver chloride

You use a precipitation method to determine [Ag+] in an unknown sample using Cl- ions. Reaction is conducted in presence of HNO3 in excess (relative to Ag+) Which statement is correct concerning the ...
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196 views

How to choose which reactants to have in excess?

In a precipitation reaction, how do I know which soluble reactant I should put in excess? E.G. $$\ce{Na2SO4 +Pb(NO3)2 -> PbSO4 + 2NaNO3}$$ In my book, $\ce{Na2SO4}$ is added in excess, but can we ...
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Precipitation of Calcium ions in basic Sodium Hydroxide solution?

I recently conducted an EDTA titration of milk to find its Calcium contents. I got a value significantly smaller than the theoretical value. (≈10 times smaller). I made $50ml$ samples to which I added ...
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559 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 ...
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337 views

How to predict precipitate upon evaporation from calcium ions and either chloride, carbonate, or nitrate counterions?

An aqueous solution containing $\ce{Ca^2+}$, $\ce{Cl^-}$, $\ce{CO3^2-}$, and $\ce{NO3^-}$ is allowed to evaporate. Which compound will precipitate first? The correct answer is $\ce{CaCO3}$. I had ...
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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 ...
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1answer
447 views

Dissociation of silver chloride in a solution

When silver chloride is exposed to light it can dissociate to silver metal and atomic chlorine. It might be a silly question, but could the chlorine go back into the solution as chloride ions ? if so ...
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1answer
482 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 ...
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1answer
324 views

Analysis of mixture by precipitation and complexometric titrations

I've performed an experiment about chloride mixtures. First using $\ce{AgNO3}$ as titrant, I've titrated the mixture to determine the amount of total chloride. Then by direct titration with $\ce{EDTA}$...
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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 ...
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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 ...
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Reaction of citric acid and calcium chloride

I was planning to extract citric acid from lemon juice by reacting the lemon juice with calcium chloride hoping it would react to form calcium citrate and precipitate according to the reaction $$\ce{...
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Original concentration calculation homework

A student performs the following gravimetric analysis of iron ions in a water system $$\ce{Fe^2+ (aq) + CO3^2- (aq) <=> FeCO3 (s)}$$ If this student used excess carbonate and obtained the ...
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How to separate sodium iodide dissolved in water?

Am fairly new to chemistry and apologize if the question and the description are too vague.If you think I lack basic background knowledge to deal with something like this, please point me to a ...
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1answer
255 views

Does precipitated copper carbonate contain impurities

I recently performed a double replacement reaction between copper sulfate and sodium carbonate to yield copper carbonate as a precipitate. I then filtered the precipitate, but I noticed that the ...
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1answer
16k views

What are the products of a reaction between copper sulfate and sodium bicarbonate?

I have been trying for a while to determine what products are produced when copper sulfate reacts with sodium bicarbonate at room temperature and standard pressure. However, while I was looking, I ...
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Generating Precipitation Diagrams with CompuTherm Pandat

I am trying to develop precipitation diagrams for an Ag-Cu-Sn alloy to figure out the kinetics involved using the CompuTherm Pandat Software (Demo Version). The precipitation diagrams need the ...
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1answer
147 views

Is NaCl in water considered “solution” despite of NaCl's having some precipitation?

Is $\ce{NaCl}$ in water aqueous? For a certain amount of $\ce{NaCl}$, it can dissolve in water but if you add more $\ce{NaCl}$ it can't dissolve any more. So, if in a certain reaction $\ce{NaCl}$ is ...
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Stoichiometry reactions for water clarification

If ferric chloride was added to a water sample which had calcium bicarbonate alkalinity present, would the reaction be a ‘stoichiometry reaction’ or a ‘limiting reagent reaction’? For example, if 1 g ...
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193 views

Is there an alternative wet chemical method or electrochemical method to obtain precipitation of iron, nickel and silicon powder? [closed]

There are many methods available to obtain powdered metals and alloys. Wikipedia show some of them. Another form is grinding with posterior removal of wheel particles. All these methods produce metal ...
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1answer
94 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 ...
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1answer
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Do all double displacement reactions have precipitates?

I know that most of the double displacement reactions form some kind of precipitates in their products. But do all of the double displacement reactions form precipitates? I have searched on this site ...
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1answer
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Is an iron (II) sulphate solution supposed to turn cloudy when silver nitrate is added?

$\ce{AgNO3}$ is not suppose to cause a precipitation when mixed with $\ce{FeSO4}$, but the acidified solution turns slightly cloudy when $\ce{AgNO3}$ is added. Is this suppose to happen? solutions ...
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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 ...
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176 views

Alkalinity in Water

If you add Alum - $\ce{Al2(SO4)3}$, to a clay water sample which contains $\ce{Ca(HCO3)2}$ - due to the water's alkalinity, the pH of this water sample would drop as Alum drops the pH levels. How ...
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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 ...
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1answer
2k 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{...
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531 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 ...
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777 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?