Questions tagged [aqueous-solution]

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

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4
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1answer
976 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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4answers
6k views

Can one predict the entropy change for aqueous phase reactions without calculation?

I have seen several sources that claim aqueous solutions always have more entropy than pure liquids or solids, however, some aqueous ions have negative standard entropy. This opens the possibility of ...
4
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1answer
283 views

Balancing Redox Equations - Half Reactions

How do I balance this using the half-reaction method: $$\ce{Zn(s) + HCl(aq) -> Zn^{2+} (aq) + H_2 (g)}$$ I would first split it up in its ionic components: $\ce{Zn(s) + H^+ + Cl^- -> Zn^{2+} (...
4
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1answer
180 views

Boiling aluminum in high-alkalinity water

This question ultimately relates to brewing beer, but more specifically to water treatment before brewing. Though I can't get a water quality report, I suspect I have high levels of bicarbonate ...
4
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1answer
76 views

Boiling solutions with two salts

If you dissolve two different ionic compounds (that don't make a precipitate) in water and then boil the solution so all the water evaporates, the salts will re-crystallize. Is it possible that you ...
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2answers
1k views

Problems with precipitation of transition metal solution

I am trying to make a solution of "trace elements"--primarily transition metals-- for use in biological media; bacteria require elements like Cobalt, Molybdenum, iron, etc. in trace amounts. I am not ...
4
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1answer
484 views

How does the composition of ice differ from that of water in a partly frozen solution?

Take any solution, then start freezing it at sufficiently low temperature. Soon a small amount of ice forms. I'd like to know how the composition of dissolved salts and gases in the bit of ice differs ...
4
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1answer
2k views

How is hydration free energy of a solute measured experimentally?

I am reading a paper (Shirts, M. R.; and Pitera, J. W. and Swope, W. C. and Pande, V. S. J. Chem. Phys. 2003, 119, 5740-5761). Near the beginning of the paper (page 5745), the authors state: ...
4
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1answer
378 views

What does m± represent in the equation for mean activity of a salt solution?

I need to find the activity $a_\pm$ for a $\pu{0.0120 M}$ solution of $\ce{Na3PO4}$, and have calculated the activity coefficient, $\gamma_\pm = 0.389$. I know that $$a_\pm = \frac{m_\pm}{m_0}\gamma_\...
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1answer
5k 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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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 ...
4
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1answer
472 views

How does monoethanolamine (MEA) increase pH?

I know pH of a solution increases with increase concentration of $\ce{OH-}$. I'm wondering: when adding MEA, is the $\ce{OH-}$ group from the MEA breaking off, or is it the whole MEA molecule taking ...
4
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1answer
461 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 ...
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1answer
3k views

Temperature change and gas evolution for vinegar and baking soda experiment

This is sort of 2 questions in 1, but I think they are related. Could someone please explain why this endothermic reaction doesn't further decrease the temperature when the amount of baking soda is ...
4
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1answer
435 views

Counterions in adsorption of ions

When an ion is adsorbed from an aqueous solution onto a solid, what happens to its counterion? Obviously, the solution does not become charged - does this mean that it too is adsorbed? (Example: $ \...
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1answer
3k 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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1answer
207 views

How do I make a dysprosium chloride solution from dysprosium oxide?

I know that dysprosium oxide is insoluble in water. I was told that I need to add concentrated $\ce{HCl}$ to the compound and then evaporate the $\ce{HCl}$ off. From looking at the reaction equation, ...
4
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1answer
140 views

Best x-ray dopant?

An x-ray computed tomography scanner has been used in an attempt to look at the pore space of a limestone rock sample (a carbonate, $\ce{CaCO3}$) saturated with a $\mathrm{12\ wt\%}$ sodium iodide ($\...
4
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1answer
191 views

Why is Iron very rare in seawater compared to many other elements?

I don't know the associated technical words to research this question. There was high presence of Iron in the oceans in anoxic precambrian times, and today copper is 5 times more abundant in the ...
4
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1answer
82 views

Colloids and Ions

Suppose I have this reaction: $$\ce{3NaOH(aq) + FeCl3(aq) → 3NaCl(aq) + Fe(OH)3}$$ My questions: $\ce{Fe(OH)3}$ doesn't have the (aq) suffix because it isn't separated in water as opposed to $\ce{...
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1answer
471 views

How would an increase in the concentration of a sucrose solution affect the rate of its acidic hydrolysis?

Regarding the acidic hydrolysis of sucrose $$\ce{\underset{sucrose}{C12H22O11} + H2O + \underset{catalyst}{H+} -> \underset{glucose}{C6H12O6} + \underset{fructose}{C6H12O6} + H+},$$ I think ...
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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 $\pu{16oz}$...
4
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1answer
391 views

Does carbonated water change over the course of several days, or was my container leaky?

I have a Klean Kanteen flip-top growler, allegedly leakproof at up to 35psi of pressure, that I filled with some freshly-carbonated water 4 days ago — just to see how long it would last. I used a Soda ...
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2answers
20k views

Electrolysis of aqueous copper (II) nitrate

There are two copper blocks sitting in the $\ce{Cu(NO3)2 (aq)}$ solution, a battery is attached onto both of them, providing enough energy to start the reaction. Since solid pieces of copper are ...
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0answers
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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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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0answers
328 views

Solubility of PbSO4

The solubility of $\ce{PbSO4(s)}$ increase with the addition of $\ce{H2SO4}.$ Why? I don't quite understand this. When dissolving $\ce{PbSO4(s)}$ we get the equilibrium equation: $$\ce{PbSO4(s) <=...
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143 views

How can copper(II) sulfate crystallize outside a glass vial?

I'm making copper sulfate crystals in glasses. Within a few weeks, the copper sulfate seems to crystallize both inside and outside the glass: (A few weeks after making a new solution) (Yet another ...
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0answers
187 views

Why does viscosity decrease when divalent cations are dissolved into aqueous solutions of sodium carboxymethylcellulose?

Sodium Carboxymethylcellulose (CMC/NaCMC/Aqualon) is a common product used in many instances for its unique properties, especially its ability to make solutions viscous. It is well known that the ...
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0answers
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How to break down soap and detergents?

I am building a greywater harvesting system. It is a 3-stage system: The 1st stage breaks down soap and detergents. The 2nd stage filters the water. The 3rd stage pumps water out of system. What ...
3
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2answers
10k views

Long-term storage of Ascorbic Acid mixed with Sodium Bicarbonate

Every day I mix two parts of ascorbic acid powder with 1 part of sodium bicarbonate powder and place the resulting powder into an airtight container. I have noticed that if the resulting powder is ...
3
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3answers
559 views

What is the compound called when it is in solution?

When a compound precipitates out of solution, for example Calcium Carbonate from a water solution, it is called the precipitate. What is the same compound called before it precipitates out - once it ...
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1answer
2k views

Reaction of aqueous sodium carbonate with aluminum foil

Aqueous sodium hydroxide is known to react with aluminum foil in an exothermic, hydrogen-gas releasing reaction like $$\ce{2NaOH(aq) + 2Al(s) + 2H2O(\ell) → 2NaAlO2(aq) + 3H2(g)}$$ However, on ...
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2answers
2k views

How to dissolve white dextrin in water?

Dextrin is labelled as highly soluble in water. I have white dextrin (analytical from Sigma Aldrich). When I mix it in water, no matter how long I stir and how little dextrin I put, I get a suspension....
3
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2answers
7k 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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2answers
253 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
180 views

Calculating pH of rain water

The concentration of $\ce{SO2}$ in the atmosphere over a city on a certain day is $\pu{10 ppm}$. Given that solubility of $\ce{SO2}$ in water is $\pu{1.3653 mol L-1}$ and $\mathrm{p}K_\mathrm{a}$ of $\...
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2answers
59 views

Precipitating silver(I) salts from the solution of barium(II) cyanate and iodide

Consider a $\pu{10.0 mL}$ solution containing $\pu{1.0e-10 M}$ each of $\ce{Ba(CN)2}$ and $\ce{BaI2}$. If $\pu{3.5e-9 mol}$ of $\ce{AgNO3(s)}$ is added to this solution, will any precipitate(s) form? ...
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3answers
637 views

What does the hydrolysis of a salt tell us about its basic/acidic character?

I'm curious to know how basicity and acidity arises when a salt or covalent compound is dissolved in water.
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2answers
184 views

Would dissolving a salt and letting it sit for 48 hours have an effect on the solution?

If one were to dissolve magnesium citrate (about $100~\mathrm{mg}$) in water (about $70~\mathrm{ml}$) and let the solution sit for 48 hours, would the solution be exactly the same as one dissolved and ...
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2answers
296 views

Use of Concentration for pH

When we find the pH of a solution, do we use normality or molarity? My teacher said that if the compound is present by itself, we can use normality but in all other cases we should use molarity. Can ...
3
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2answers
793 views

Is Fe(OH)2 soluble in alkalis?

I have just started inorganic chemistry in school and I have just learnt about metal aqua ions and how they react in water. I learnt that $\ce{[Fe(H2O)6]^2+}$ reacts in water by losing a $\ce{H+}$ ...
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1answer
2k views

Which is more soluble in water, HF or SO2?

I was wondering which is more soluble in water, hydrogen fluoride or sulfur dioxide? Since $\ce{HF}$ will hydrogen bond to other HF particles (as opposed to $\ce{SO2}$ dipole-dipole attraction). ...
3
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2answers
617 views

How might one reduce the concentration of bubbles in their ice, from ice cube trays?

So I have been freezing ice a lot recently, and I will come out and say it, as it turns out it is, albeit unlikely, it is sometimes possible for ice to "explode." I was not so aware of this before, ...
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2answers
315 views

Diluting 4 % NaOCl to get a 1 % solution

Assuming that one has a 1 litre bottle of liquid bleach containing $4~\%$ sodium hypochlorite. If I wish to dilute it down to $1~\%$ sodium hypochlorite (to use as disinfectant), would adding 3 litres ...
3
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2answers
281 views

Partial reactions in redox formation of rust

In the iron oxidation that results in rust, the first step is to steal 2 electrons from $\ce{Fe}$. The main thief is said to be the oxygen dissolved in water, witch uses the stolen electrons to form $\...
3
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1answer
194 views

How to solve for concentration of two equilibrium reactions with finite equilibrium constants?

I have a small problem of equilibrium that I counldn't solve. I want the exact answer. No approximations please. $$ \begin{array}{ll} \ce{H2O + H2O <=> H3O+ + OH-} &\quad\left(K_w = 1\cdot ...
3
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1answer
134 views

Adding ethanol to louche

I'm watching MIT chemistry by Donald Sadoway. In one of his lectures devoted to solutions and phase separation, he performs experiments with absinthe. First he mixes absinthe with 5 $\times$ water ...
3
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2answers
18k views

Why bother to standardize a solution?

I have been preparing lessons for some of my students about preparing acidic and basic solutions, and I keep finding pre-made labs in which the students "standardize a basic solution" by titrating it ...
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2answers
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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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