Questions tagged [aqueous-solution]
For questions relating to compounds dissolved in water and resulting reactions and acid-base equilibria.
1,039
questions
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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 ...
5
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0answers
64 views
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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1answer
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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1answer
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
$$
\begin{align}
\ce{...
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1answer
44 views
Dissociation equilibria of ammonium bifluoride in water
Ammonium bifluoride or ammonium hydrogen fluoride is a salt of a weak base and a weak acid.
The weak acid is because the second equilibria of $\ce{HF}$ written as:
$$\ce{HF + F- <=> HF2-}$$
and ...
1
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0answers
32 views
Does aqueous ammonium fluoride solution release hydrogen fluoride vapors?
Can $\ce{HF}$ vapors be released from $\ce{NH4F}$ solution in water $(w(\ce{NH4F}) = 40\,\%)$ at room temperature?
I assume that dissolving $\ce{NH4F}$ in water produces small amount of $\ce{HF}.$
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28 views
Destroying micellar particles using electrolytes
I learnt that micellar particles formed by ionic detergents forms due to the negative charges of H2O molecules are facing the solution, hence micellar particles repel each other.
I also learnt that ...
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1answer
34 views
Aluminum electrodes for NaCl [duplicate]
Upon using aluminium Electrodes for a concentrated solution of NaCl, i conducted electrolysis on the solution for nearly 4-5 hours. There was definitely a gas possibly hydrogen being evolved at the ...
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0answers
27 views
Ionic product value and pH/pOH
when studying basic acid and base reactions I got some conceptual question. When calculating the pH or the pOH of water we use the following formula:
$$\mathrm {pH}+\mathrm{pOH}=14$$
This comes from ...
0
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2answers
43 views
Seeking safe, water-soluble chemicals for an IR spectroscopy experiment
I am working with a custom-built device which is intended to perform some mid-infrared chemical measurements. It consists of four thermopile sensors with optical windows. In front of each window is ...
0
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1answer
53 views
Why do bubbles form and stay when I shake a bottle of tea?
I have some bottled tea and I noticed that shaking it creates some foamy bubbles that stay for quite a while (at least half an hour if not more). I originally thought it has something to do with my ...
5
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47 views
leaving a spoon in a cup of tap water for about 12 hours makes a pattern of bubbles, why? [closed]
I left the spoon in the water after showing the cup from the tea that I was drinking last night makes a spoon like the pattern of bubbles
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1answer
43 views
How to prepared saturated salt solution (NaCl)? [closed]
What do they mean by "add 321 g saturated NaCl solution"? Description does not contain volume.
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65 views
Neutralisation reaction of HCl (aq) + NaOH (aq): How NaCl forms?
Consider the neutralisation reaction
$$\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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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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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
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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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,...
0
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1answer
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 $\...
7
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1answer
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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2answers
99 views
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^-$$
If so, that means that $NaO^-$ is a base, which would make $NaOH$ it's conjugate ...
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1answer
51 views
Balancing complex redox reaction of gold treated with sodium cyanide
How would you balance this reaction:
$$\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 ...
0
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1answer
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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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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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 ...
3
votes
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, ...
1
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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 ...
2
votes
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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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}$$
I am not really sure if ...
4
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2answers
52 views
How do I calculate the amount of preservatives one would need for a cleaning solution?
I plan on making a very simple cleaning solution to clean metal contacts on PCB boards. It cannot contain anything that is flammable or hazardous so I've come up with the solution below.
Distilled ...
2
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0answers
24 views
Calculating the solubility for chromium(III) hydroxide using the complex ion constant
Problem
$$
\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_\...
1
vote
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
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 ...
0
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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 ...
2
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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
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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27 views
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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2answers
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 ...
2
votes
1answer
50 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 ...
2
votes
2answers
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 ...
3
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1answer
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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40 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 ...
4
votes
2answers
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 ...
0
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1answer
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 ...
0
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1answer
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 $\ce{CO2}$....
0
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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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0answers
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 ...
2
votes
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
...
0
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1answer
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 ...
