Questions tagged [aqueous-solution]

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

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29 views

pH of an aqueous solution of Mg2+ kept rising above that of clean water. What's going on?

In a recent inorganic chemistry lab session, we tested the pH of various ions in water. The water turned out to be on the acidic side (5.5 with $\mathrm{pH}$-paper, 5.59 with $\mathrm{pH}$-meter). A ...
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What pH value of 1M sodium crotonate solution supposed to be?

I need to prepare the $\pu{1M}$ solution of sodium crotonate, however, I don't have one in lab, but I do have sodium hydroxide and crotonic acid. Thus, I calculated that for $\pu{100 mL}$ of $\pu{1M}$ ...
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31 views

Disparity between LeChatelier's Principle and Solutions

Let's say that there is a solution $\ce{Na+(aq) + Cl-(aq) <=> NaCl(s)}$ If the above solution is at equilibrium we can say that it is saturated and hence no more Sodium Chloride will dissolve. ...
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33 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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44 views

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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32 views

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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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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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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27 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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43 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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1answer
53 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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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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43 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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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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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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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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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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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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57 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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158 views

Aspirin Hydrolysis at pH 2

Conducting an experiment, I found that very little salicylic acid was evolved performing hydrolysis at $\mathrm{pH \ 2}$ and at $\pu{45 ^\circ C}$. In fact, far more salicylic acid was evolved at $\...
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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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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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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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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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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
94 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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1answer
74 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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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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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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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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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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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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41 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
50 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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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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106 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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107 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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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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303 views

Do strong acids actually dissociate completely?

Do strong acids actually dissociate completely (every single molecule dissociates), or are they just assumed to do so for the sake of simplicity? That seems odd, considering weak acids, many of which ...
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141 views

What is the difference between these two formulas for pH of weak acids?

In the German Wikipedia article on $\mathrm{pH}$, I found the following formula for calculating the $\mathrm{pH}$ of weak acids (which are there defined of having $4.5 < \mathrm{p}K_\mathrm{a} < ...
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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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56 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 ...
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45 views

When blue vitriol is dissolved in water [closed]

when CuSO4.5H2O is dissolved in water, what physical and chemical effects happens to its water of crystallization? While solving a stoichiometric problem the ques was that 1litre of CuSO4.5H2O was ...
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319 views

Can Anyone Explain the Mechanism of the Birnbaum-Simonini reaction?

When silver acetate reacts with iodine and $\ce{CCl4}$, it gives esters and 2 moles of $\ce{AgI}$ but when it reacts with iodine and lead acetate, why it gives alkyl halide, $\ce{AgI}$ and $\ce{CO2}$....
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1answer
52 views

Calculating the density of a magnesium sulphate solution

I am trying to calculate the density of a magnesium sulphate solution and came across this paper which determines an equation from experiment to do that. However, I am having trouble understanding the ...
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28 views

Aluminum Monoacetate Solubility in Aqueous Medium?

Does anyone have access to the aqueous solubility value of aluminum monoacetate? I would expect it to be slightly soluble but I've searched the internet and haven't found any solubility values. : /
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1answer
47 views

Basic behavior of ammonia in aqueous medium [closed]

Thanks to the reversible reaction $$\ce{NH3 + H2O <=> NH4+ + OH-},\tag{R1}$$ we know that ammonia acts as a weak base. However, I was wondering why it ends up forming ammonium $\ce{NH4+}$ and ...
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1answer
41 views

What is the mechanism of endothermic dissolution?

My real question is in fact "How can dissolution happen if it's endothermic?" However, there have been many questions regarding this exact topic and the answers about Gibbs free energy ...
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44 views

Water solubility of different types of Iron III

For an experiment I require an aqueous solution of Iron(III). My school has the following compounds, which of them are water soluble? I believe that only Iron(III) oxide is insoluble, but I would like ...

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