Questions tagged [aqueous-solution]

For questions relating to compounds dissolved in water and resulting reactions and acid-base equilibria.

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12
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3answers
35k views

Differentiation between zinc, aluminium, and magnesium ions in solution

If I have three aqueous ionic solutions in which I know that the cation is $\ce{Al^3+}$, $\ce{Mg^2+}$, or $\ce{Zn^2+}$, how do I find out which is which? I was thinking to add $\ce{OH-}$ in the form ...
6
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2answers
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Why does CO2 lowers the pH of water below 7?

Ok so I understand that having a pH below 7 is considered to be acidic and I also understand that part of the definition of an acid is that it gives off H+ when dissolved in water(even though not all ...
5
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1answer
58k views

Preparation of iodine solution

How to prepare $\mathrm{0.1M}$ $\ce{I_2}$ solution. I have found in books that it should be prepared in $\ce{KI}$ solution but none of them explains why? Please explain in detail not just the ...
3
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2answers
3k views

Why doesn't water play a role in reactions in aqueous reactions?

$$\ce{Ba(NO3)2(aq) + Na2CO3(aq)}$$ In the above reaction both the substances are in water, however water plays no role in the reaction. Why is it that although water is present in the reaction, it ...
3
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2answers
4k views

Why doesn't a buffer solution change ph(Appreciably?)

Consider a buffer solution containing weak acid $\ce{CH3COOH}$ and its salt $\ce{CH3COONa}$: \begin{align} \ce{CH3COOH &<=> CH3COO- + H+} \tag{1}\\ \ce{CH3COONa &-> CH3COO- + Na+} \...
13
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2answers
6k views

Why are synthetic pH indicators used over natural indicators?

Synthetic indicators seem to be exclusively used when determining the pH of a substance with an indicator (with the exception of that school experiment where you boil cabbage to demonstrate natural pH ...
12
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1answer
307 views

What might serve as an initial starting photocatalyst for this large water-splitting solar simulator?

Question: What might serve as an initial starting photocatalyst for this large water-splitting solar simulator? Surely there must have been some planned experiments! The Gizmodo article Insane Light ...
12
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2answers
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Would sodium explode in salt water?

I’ve seen the video etc of sodium being put into freshwater and the reaction of flames/small explosion but I wonder if the same reaction would occur if conducted in salt water such as the ocean.
9
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2answers
783 views

Why does Devarda's alloy include copper?

Devarda's alloy is used in the detection of nitrates. However, judging by the reaction equation, only aluminium plays the role of reducer: $$\ce{3NaNO3 + 8Al + 5NaOH + 18H2O -> 8Na[Al(OH)4] + 3NH3(...
9
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1answer
19k views

Why do some substances ionize instead of dissolving in water?

My question can also be understood as what make something electrolyte or nonelectrolyte? I think this question stems mainly from my confusion with the definitions of ionizing and dissolving. ...
6
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1answer
4k views

Hybridization of Na in [Na(H2O)6]+

In the complex ion $\ce{[Na(H2O)6]+}$, the sodium cation forms 6 coordinate bonds with water ligands. Typically this octahedral form is associated with $\mathrm{sp^3d^2}$ hybridization as far as I ...
6
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2answers
12k views

Azeotropes and separation by distillation?

I have just recently learnt the theory of fractional and normal distillations and the basics of maximum and minimum boiling azeotropes. Most books say that the components of the mixture forming an ...
3
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1answer
872 views

Predicting pH of an acidic salt of an weak acid and weak base

Suppose we want to calculate pH of an $\ce{NH4HCO3}$ solution of known concentration. Now, $\ce{NH4+}$ will be hydrolised to give $\ce{H+}$ ions. Some $\ce{HCO3-}$ ions will be converted to (i) $\ce{...
2
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1answer
453 views

Why is water instead of hydroxide ions used to balance oxygen atoms in redox half equations?

When balancing half equations of redox reactions, $\ce{H2O}$ is used to balance any oxygen atoms? For example, this half equation $$\ce{NO3- → NH4+}$$ is balanced into: $$\ce{NO3- + 8 e- + 10 H+ → ...
22
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3answers
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Is "Sulfuric acid... makes a poor electrolyte... very little of it will dissociate into ions" really true? What does that actually mean?

While researching chromate conversion coating for edits to this answer in Space Exploration SE, I came upon the following passage in Corrosion Resistance of Stainless Steel to Sulfuric Acid Sulfuric ...
16
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1answer
885 views

Why does the graph of the electrical conductivity of sulfuric acid/water solutions have this knee in the ~85%-~92% range?

This answer to an earlier question regarding the electrical conductivity of sulfuric acid provides a graph showing the conductivity of sulfuric acid/water mixtures ranging from 0% to 100% sulfuric ...
13
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3answers
49k views

If caffeine is an alkaloid, why is coffee acidic?

I have just put together on my mind these two facts: caffeine is an alkaloid and brewed coffee is slightly acidic (pH = 5). My Biology teacher and my Chemistry teacher could not elaborate satisfying ...
9
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1answer
2k views

How could alcohol be made into a powder?

In the news recently is 'Palcohol', powdered alcohol, that you add to water or existing liquids to make it alcohol. Presumably this would dissolve and break apart into alcohol and {some other compound}...
6
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1answer
19k views

Is there a way to calculate how fast water will cool?

Is there a way to calculate how fast water will cool if you know the water's starting temperature and temperature of the environment that you put it in, such as a freezer?
5
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2answers
38k views

Does dissolving salt in water change the pH?

I am particularly interested in the effect or lack of effect of dissolved NaCl in regards to pH in water. It would be interesting also if anyone has any insight for other salts and their effects. ...
4
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1answer
1k views

How can I calculate the molar conductivity of a solution with multiple solutes?

I'm running an experiment mixing 2 different solutions, $\pu{5 mL}$ of $\pu{0.1 M}$ $\ce{NaCl}$ with $\pu{5 mL}$ of $\pu{0.1 M}$ $\ce{KCl}$. I am measuring the conductivity of the total solution in $\...
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1answer
6k views

Hypochlorous acid mechanism

When hypochlorous acid is dissolved in water, is it the chlorine atom or the oxygen that serves as the anti microbial agent?
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3answers
79k views

How to convert from w/w% to molarity?

After reading a number of explanations about it after googling, I'm a bit confused on this. Some explanations are doing it using a solution density, others aren't, though most are. On one site it's ...
0
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1answer
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Why are the reactants in the solubility product constant multiplied by their coefficients and raised to the power of their coefficients?

It is probably easiest for me to explain the question in an example. Consider the following chemical reaction: $\ce{MgF2(s) -> Mg^{2+} (aq) + 2F- (aq)}$ Plugging this into the formula for the ...
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1answer
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Is Phosphate (PO4 3-) solube in water? [closed]

Josh~ Superphosphate is used instead of just phosphate because superphosphate is a compound whereas phosphate is an ion. This means that phosphate must attach itself with a cation in order to give a ...
12
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2answers
468 views

Water exchange at Al (III)

Why is the rate of water exchange at Al(III) centres so slow ? According to this medical book (p.5) it is $10^{5}$ times faster at Mg(II).
11
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2answers
377 views

Vapor Pressure Paradox

This is quite an interesting situation I had thought of. Consider two beakers, each containing $\pu{180 g}$ of water. Also, suppose one of the two has $\pu{1.8 g}$ of glucose dissolved in it. Let's ...
10
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1answer
6k views

Why aren't the copper(II) ions in CuSO4 precipitated by hydroxide ions from water?

From my own experience and literature, I know that $\ce{CuSO4}$ is well soluble in water and dissociates into $\ce{Cu^2+}$ and $\ce{SO4^2-}$. $\ce{Cu(OH)2}$, however, is not: $K_\mathrm{sp} = 2 \cdot ...
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2answers
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Can sodium bicarbonate be considered an acid?

I was reading about acids and bases today and finally decided to question the statement that "baking soda is a base." Let's start with the dissolving of baking soda, $\ce{NaHCO3}$. The equation to ...
8
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2answers
5k views

Can lead(II) oxidize tin metal in aqueous solution?

According to my textbook, element $\ce{X}$ can oxidize element $\ce{Y}$ if $\ce{X}$ was lower in the activity series. Lead is lower than Tin in the activity series table in the textbook, but the ...
8
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2answers
397 views

Looking for caffeine partition coefficients

As part of a project, I'm looking to carry out a liquid-liquid extraction of caffeine from an aqueous phase to an organic phase, using dichloromethane or ethyl acetate. So I'm looking for the ...
7
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3answers
31k views

If you add AlCl3 to water, why does the pH decrease?

You are not adding any hydrogen ions, so why does the pH of the solution decrease? Thank you in advance. EDIT: I will add the context of my asking this question to clarify some details. This is not ...
6
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1answer
3k views

What are the active ingredients of shampoo, and how do they work?

After seeing one too many TV commercial about the fantastical properties of different high-profile shampoo products all "with documented effect" it suddenly struck me that I never actually researched ...
6
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0answers
4k views

Is iron(III) carbonate stable in water?

I searched for this onsite already, and also found the following answer on Quora: In aqueous environment, iron(III) is bound by water molecules and exists as $\ce{[Fe(H2O)6]^3+}$. Due to strong ...
6
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3answers
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Will this reaction form magnesium carbonate?

I have magnesium oxide pills I take. I know if I dissolve them they'll form magnesium hydroxide, and I'm trying to make pure magnesium from my pills. I've come up with a double replacement reaction, ...
6
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5answers
22k views

How to dissolve steel without affecting aluminium alloy

Disclaimer: I have very limited knowledge of chemistry My problem is the following: I have motorcycle part made from some sort of Aluminium alloy - most probably 6005, 6061-T6 or 7005. And inside of ...
6
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1answer
599 views

Trichloride ion (c.f. triiodide ion)

While triiodide ion is commonly known, why is that trichloride ion (and its salts) almost unheard of? While it does exist according to literature, why is the stability of trichloride ion in aqueous ...
5
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1answer
2k views

Why does pouring soda slowly and smoothly seem to keep more of the carbonation?

So, I caught myself gently pouring a can of soda into a cup of ice (making sure that there was room for air to move through so the stream of soda from the can to the cup was consistent and even) ...
5
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1answer
2k views

How is NaOH able to clear a solution of Paraformaldehyde?

While making a solution of $4~\%$ para-formaldehyde for immunohistochemistry (to fix the tissue), we add para-formaldehyde into water and stir. It looks like a chalky supersaturated solution even ...
5
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2answers
561 views

Decrease in temperature of an aqueous salt solution decreases conductivity

Why does the conductivity of a water solution drop as the temperature decreases? How are these two related?
5
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2answers
22k views

How much carbonation is in one liter of commercial fountain Coca-Cola

From what I understand generally Coke is carbonated to roughly 6.2 g per liter in bottles and cans, or 3.1 volumes of CO2. I was watching this video because I was curious about how fountain soda ...
5
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1answer
240 views

Why is the aqueous solution of KMnO4 slightly basic?

This is in the context of the various changes in oxidation state the permangananate ion can undergo with the variation of the pH of the medium. Besides the cases of strongly basic and strongly acidic ...
5
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2answers
2k views

Does H2CO3 exist in solution?

When $\ce{CO2}$ reacts with water, it supposedly forms $\ce{H2CO3}$, which is the aqueous form of $\ce{CO2}$. But it is hard to isolate, but its $K_\mathrm{a}$ value is pretty low (on the order of $10^...
5
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2answers
4k views

Is lithium bicarbonate an aqueous solution of lithium carbonate?

This question is related to: Are Lithium bicarbonate and​ Magnesium bicarbonate both soluble in water? What type of chemical reaction is this? How can bromine water be called a solution? In the ...
4
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1answer
581 views

Why do aqueous solutions always have to be electrically neutral?

I was reviewing some analytical chemistry and stumbled upon a section that explained the imperfection of using a salt bridge. It said that the using dissimilar ions is a problem because in, for ...
4
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1answer
506 views

How many protons does phenolphthalein lose in basic solutions?

So, I've looked it up and Wikipedia claims that two protons are released by Phenolphthalein when pH is over 8.2, but I've seen other sources that claim only one proton is lost. So, is it really just ...
4
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2answers
3k views

Why is water ignored in the ionic equilibrium of HF?

While trying to understand the solution of a problem given in my textbook, I realized I'm having some difficulty with the solution. The problem is as follows: The ionization constant of $\ce{HF}$ ...
3
votes
2answers
332 views

Disproportionation of silver(I) in aqueous solution

Use the following equations to predict whether or not $\ce{Ag+}$ ions will disproportionate in solution: $$ \begin{align} \ce{Ag+(aq) + e- &-> Ag} &\qquad E^\circ = \pu{+0.80 V}\\ \ce{Ag^2+(...
3
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2answers
8k views

Why would a solution of FeCl2 appear brown/yellow sort of like FeCl3?

If we prepare a solution of $\ce{FeCl2}$ by dissolving solid $\ce{FeCl2}$ powder in water, supposing the bottle of $\ce{FeCl2}$ was left open for sufficient time, is it possible for $\ce{FeCl2}$ to ...
3
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0answers
63 views

Molar ratios not leading to complete reaction in Schweizer's reagent production

In my home lab, I've reacted $\ce{Cu(OH)2}$ with aqueous ammonia to produce Schweizer's reagent. However, I'm surprised by the amount of ammonia required to react with this amount of $\ce{Cu(OH)2}$. ...