Questions tagged [aqueous-solution]

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

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25 views

Why is the solution of ammonium bifluoride more acidic than aqueous ammonium fluoride?

At low concentrations of aqueous $\ce{NH4HF2}$ $(w = 1–2\,\%)$ $\mathrm{pH}\approx 3.$ But aqueous $\ce{NH4F}$ $(w = 20–40\,\%)$ has $\mathrm{pH}\approx 7.$ Yet the equilibria of $$ \begin{align} \ce{...
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68 views

How does strong acids conduct electricity in water?

How do strong acids conduct electricity in water? I have just studied ionization of water and I'm confused about some points. First: I know that water ionizes in a very small amount ($10^{-14}$) so ...
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1answer
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Dissociation equilibria of ammonium bifluoride in water

Ammonium bifluoride or ammonium hydrogen fluoride is a salt of a weak base and a weak acid. The weak acid is because the second equilibria of $\ce{HF}$ written as: $$\ce{HF + F- <=> HF2-}$$ and ...
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2answers
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How is NaOH a base? [closed]

Firstly, how is $NaOH$ created? My teacher said that before it is $NaOH$, it is $NaO^-$. $$NaO^- + H_2O = NaOH + OH^-$$ If so, that means that $NaO^-$ is a base, which would make $NaOH$ it's conjugate ...
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0answers
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Does aqueous ammonium fluoride solution release hydrogen fluoride vapors?

Can $\ce{HF}$ vapors be released from $\ce{NH4F}$ solution in water $(w(\ce{NH4F}) = 40\,\%)$ at room temperature? I assume that dissolving $\ce{NH4F}$ in water produces small amount of $\ce{HF}.$
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3answers
267 views

Tap water pH adjustment using citric acid

I've lowered tap water pH from 7 to 6 using citric acid. After couple of hours pH raised again to 7. What is the reason for this raise? Citric acid overcomes waters buffering feature then raise the $...
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0answers
28 views

Destroying micellar particles using electrolytes

I learnt that micellar particles formed by ionic detergents forms due to the negative charges of H2O molecules are facing the solution, hence micellar particles repel each other. I also learnt that ...
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1answer
32 views

Aluminum electrodes for NaCl [duplicate]

Upon using aluminium Electrodes for a concentrated solution of NaCl, i conducted electrolysis on the solution for nearly 4-5 hours. There was definitely a gas possibly hydrogen being evolved at the ...
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0answers
26 views

Ionic product value and pH/pOH

when studying basic acid and base reactions I got some conceptual question. When calculating the pH or the pOH of water we use the following formula: $$\mathrm {pH}+\mathrm{pOH}=14$$ This comes from ...
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1answer
2k views

Get the molar mass of an unknown liquid in a dissolution

A dissolution has $10$g of some unknown liquid and also $90$g of water. The freezing point of this dissolution is $-3.33^\text{o}$C. What is the molar mass of the unknown liquid in g/mol? Alright....
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1answer
52 views

Why do bubbles form and stay when I shake a bottle of tea?

I have some bottled tea and I noticed that shaking it creates some foamy bubbles that stay for quite a while (at least half an hour if not more). I originally thought it has something to do with my ...
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2answers
42 views

Seeking safe, water-soluble chemicals for an IR spectroscopy experiment

I am working with a custom-built device which is intended to perform some mid-infrared chemical measurements. It consists of four thermopile sensors with optical windows. In front of each window is ...
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46 views

leaving a spoon in a cup of tap water for about 12 hours makes a pattern of bubbles, why? [closed]

I left the spoon in the water after showing the cup from the tea that I was drinking last night makes a spoon like the pattern of bubbles
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1answer
41 views

How to prepared saturated salt solution (NaCl)? [closed]

What do they mean by "add 321 g saturated NaCl solution"? Description does not contain volume.
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2answers
50 views

How do I calculate the amount of preservatives one would need for a cleaning solution?

I plan on making a very simple cleaning solution to clean metal contacts on PCB boards. It cannot contain anything that is flammable or hazardous so I've come up with the solution below. Distilled ...
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4answers
1k views

Causing a metal or glass marble to float in an aqueous solution

I am trying to find a way that you could cause metal (Aluminum) or glass to float in a mixture of water and some water-soluble material. I am aware that salt can be used to heighten the density of ...
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0answers
63 views

Neutralisation reaction of HCl (aq) + NaOH (aq): How NaCl forms?

Consider the neutralisation reaction $$\ce{HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)}.$$ I am struggling to understand what happens to $\ce{Cl}$ in this reaction, and how it joins with $\ce{Na}$. $\...
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1answer
72 views

MgO as food supplement - solubility in water

A number of magnesium food / sports supplements contain it as MgO - which is practically unsoluble in water. The recommended quantity is somewhere around .3g / day, so not an insignificant amount. How ...
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0answers
19 views

How to know which way to calculate an extraction

I have been solving a number of extraction problems and thought I had figured out how to solve each problem depending on if I started in an aqueous solution or in an organic solution. However, I just ...
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0answers
27 views

Why does vapor pressure of ice decrease faster than water when temperature decreases?

In melting point depression, I have learnt the explanation from the textbook that (e.g. aq. solution): Definition of melting point: ice and water exist in equilibrium (have the same vapor pressure). (...
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1answer
50 views

Common Ion Effect explanations

From my textbook, it is stated that: e.g. If we add a basic salt $\ce{NaF}$, it will fully dissociate to give $\ce{F-}$. Then if we add $\ce{HF}$, since it is a weak acid, the high concentration of $\...
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1answer
59 views

How does solutions of two liquids work? [closed]

When two liquids mix, and they are not hindered by a polarity mismatch (like oil and water), why don't they always form a homogenous mixture? Due to entropy, a liquid will disperse itself evenly. This ...
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1answer
46 views

Converting w/v to mole fraction

If I have 10 mL 0.9% w/v $\ce{NaCl}$ solution, I can deduce that the solution contains 0.09 g of $\ce{NaCl}$. Imagine that this is standard laboratory conditions and 1 ml = 1 g is acceptable. Is the ...
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86 views

Aspirin Hydrolysis at pH 2

Conducting an experiment, I found that very little salicylic acid was evolved performing hydrolysis at pH 2 and at 45 degrees C. In fact, far more salicylic acid was evolved at pH 7. This comes as a ...
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38 views

Which solute depresses the freezing point of water the most?

I am curious which solute depresses the freezing point of water the most. I know that NaCl depresses it to about -21 C, but was wondering what would be the lowest freezing point of water you could get,...
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1answer
73 views

Identification of aqueous solutions of sodium hydroxide, sodium acetate and potassium thiocyanate using nickel(II)

I'm very new to chem — taking an intro to chemistry course where we are currently focused on substance identification. I have two substances, both aqueous solutions of either $\ce{NaOH},$ $\ce{KSCN},$ ...
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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 ...
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1answer
51 views

Balancing complex redox reaction of gold treated with sodium cyanide

How would you balance this reaction: $$\ce{Au(s) + NaCN(aq) + O2(g) + H2O(l)-> Na[Au(CN)2](aq) + NaOH(aq)}?$$ Here’s what I’m came up with. First we can balance any atoms besides hydrogen and ...
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0answers
30 views

What happens to dissolved ions when an aqueous solution evaporates?

I'm working on a chemical design project where zeolite crystals containing $\ce{Na+}$ cations is ion-exchanged via an aqueous solution of $\ce{AgNO3}$, $\ce{Cu(NO3)2}$, and $\ce{Zn(NO3)2}$, also ...
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1answer
45 views

Indirectly Measuring Diffusion of NO2 into Water

I am working on a data science project with the central hypothesis is that air-born pollutants can become water-born through diffusion. The example I am using as a proof of concept is $\ce{NO2}$. The ...
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3answers
6k views

Electrolysis of aqueous lead nitrate

When going through one of my chemistry textbooks, I saw that the electrolysis of aqueous lead nitrate led to oxygen being formed at the anode and lead being formed at the cathode. However, in school, ...
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1answer
73 views

Finding Ka of a monoprotic weak acid from pH and concentration of added sodium salt

A solution of $\pu{0.36 M}$ of the sodium salt of a generic monoprotic weak acid $\ce{HA}$ has a $\mathrm{pH}$ value of $8.782.$ $K_\mathrm{a} = ?$ Why doesn't the following formula work in this ...
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0answers
14 views

HCl Concentration vs HDPE Permeation

I've learned that HCl escapes HDPE. I looked up why and it turns out it's because of the small size of the molecule. That factor is unlikely to be affected by the concentration of HCl in water, but I ...
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1answer
83 views

Preparation of ammonium acetate buffer for HPLC

Buffer solutions are typically prepared by dissolving an appropriate salt in water and then adjusting the $\mathrm{pH}$ to the desired position by addition of the conjugate acid or base. For example, ...
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2answers
89 views

Criterion for gravimetric analysis of silver

If the only criterion for gravimetric analysis of silver is solubility of precipitate, which one of the following two compound are we supposed to choose? $K_\mathrm{s}(\ce{AgCl}) = \pu{1.78E-10}$ and ...
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2answers
67 views

Does carbonation permanently increase the acidity of soda water?

If you carbonate water, and then expose the resulting soda water to the atmosphere and wait until it goes completely flat, will the (former) soda water end up more acidic in final equilibrium than ...
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0answers
70 views

Nernst equations for the reduction of sulfate(IV) and nitrate(V) anions

Write a Nernst equation $(\pu{25 °C})$ for system: $$\ce{SO3^2- + 3 H2O + 6 e- -> S^2- + 6 OH-}\tag{R1}$$ and system: $$\ce{NO3- + 3 H+ + 2 e- -> HNO2 + H2O}\tag{R2}$$ I am not really sure if ...
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0answers
24 views

Calculating the solubility for chromium(III) hydroxide using the complex ion constant

Problem $$ \begin{align} \ce{Cr(OH)3(s) &<=> Cr^3+(aq) + 3 OH-(aq)} &\quad K_\mathrm{sp} &= \pu{6.7E-31} \\ \ce{Cr^3+(aq) + 4 OH-(aq) &<=> Cr(OH)4-(aq)} &\quad K_\...
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2answers
6k views

Lugol's iodine 5 % aqueous solution

There is Lugol's 5 % solution with 5 g of pure iodine and 7.5 g of potassium iodide. In one ml there should be 12.5 mg of iodine in sum. But there are suggestions telling that two drops of this ...
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1answer
31 views

Does PEO particle size decrease when dissolved in water?

I am looking to make metallic ink for inkjet printing and using PEO 1 wt% (MW ~600,000) as a binder. The print head I am hoping to use has a nozzle diameter of 80 microns. The metal powder dispersed ...
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0answers
39 views

Problem in the calculation of ionic strength of a solution

Recently I've been trying to answer the question 10-13 (c) of 9th edition of Fundamentals of Analytical Chemistry of Skoog et al. Comparing my answers with the student manual , I realized that my ...
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1answer
49 views

Why are some weak acid equilibrium approximations invalid in very dilute solutions?

Using two approximations for the dissociation of a weak acid, we can write $$K_\mathrm{a}= \frac{[\ce{H+(aq)}]^2}{[\ce{HA(aq)}]}$$ One of these two approximations we use is that the concentration of ...
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0answers
43 views

Why does sodium citrate in water turn black when blueberries are added?

I recently started making oral rehydration therapy for someone I'm taking care of who developed POTS after COVID-19 infection. (ORT was recommended by their doctor.) I use the standard ingredients of ...
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1answer
90 views

pKa = pH for strong acid — strong base?

I have learnt that for a weak acid — strong base titration, $\mathrm{p}K_\mathrm{a} = \mathrm{pH}$ at the half equivalence point. However, the same conclusion is not drawn when discussing strong acid —...
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When multiple sources give the content of an ingredient my an unqualified percentage, can I safely assume this is by weight? Or; it's not a wart

I am trying to make a simple scented shampoo and body soap for my own use and for Christmas gifts. I statr with a base of 32 oz – (a bit under a kg) of a mild commercial castille soap (Dr. Bronner’s ...
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39 views

Molarity of a mix between solid and solution

$\pu{50 g}$ of solid $\ce{NaOH}$ is added to $\pu{1.5 L}$ of $\pu{2.4 M}$ $\ce{NaOH}.$ Water is then added to the mix until the solution reaches $\pu{5 L}.$ I need to find molarity of the final ...
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2answers
99 views

Why does a proton react with water to form hydronium ion and why does that ion has an overall positive charge? [closed]

Take this is an example: $$\ce{HCl(aq) -> H^+(aq) + Cl^-(aq)}$$ and $$\ce{HCl(aq) + H2O -> H3O+ + Cl^-(aq)}$$ Clearly the proton latches on to the water molecule but why? Also, why does the ...
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1answer
3k views

How to interpret the instruction of the dilution of hydrogen peroxide?

I am required to prepare $\pu{120cm3}$ of hydrogen peroxide to each of one of my students tomorrow. Some material is given to me on the method of preparing the solutions. Within the method of ...
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1answer
48 views

Does CH3COOH + H2O (vinegar) lose its antibacterial and antiviral properties when exposed to air?

I have been reading about using CH3COOH + H2O (vinegar) as a mild antibacterial and antiviral agent. For example: https://pubmed.ncbi.nlm.nih.gov/15698693/ Note, before anyone gets confused (or ...
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2answers
6k views

Best way to dissolve/emulsify beeswax and carnauba wax in water-based solution

What I can use to dissolve beeswax and carnauba wax and keep it in an aqueous solution? I do not want to use ethanol or acetone as they are too harsh. I am adding about $\pu{5\%}$ wax to a $\pu{16oz}$...

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