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13 votes
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Possible technique for measuring pH in solutions

Measuring pH with current flowing is not an appropriate idea. You would like to measure something without chemically disturbing the system. The moment you pass current in a solution, you start to ...
ACR's user avatar
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4 votes
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How to correct for acidic water when taking the pH of a soil/water solution?

Regrettably, one cannot simply add or subtract pH to correct for that error. Correction would depend on knowing how much and what type of each contaminant was in the water. For example, a very dilute, ...
DrMoishe Pippik's user avatar
4 votes

Are there LCMS compatible buffer systems available for the high pH range 12-14?

First off, as a comment implies you need the right column. Silica-based columns are not suitable for high $\pu{pH}$, even $\pu{pH }8$ can cause problems according to a now-deleted comment in the ...
Oscar Lanzi's user avatar
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4 votes

Can pure hydronium exist?

$\ce{H3O+}$ is a ion – a charged particle. As an isolated ion, "naked" in vacuum or gas, or hydrated in water, it is a common thing. But with macroscopic quantities, it is more complicated. ...
Poutnik's user avatar
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4 votes

Can a multimeter be used to measure PH?

A multimeter measures resistance, i.e., the blocking of electron (or ion) flow. A pH meter measures the voltage difference between glass-encased electrodes. As you might realize, silica-based glasses ...
DrMoishe Pippik's user avatar
4 votes

By how much does sodium bicarbonate raise pH?

There is more to changing pH than just Sodium Bicarbonate(at least for pools). It is important to consider factors such as Calcium Hardness, Total Dissolved Solids, and temperature before making an ...
Ronith's user avatar
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3 votes
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Can carbonic acid form a salt with pH < 7?

Both ammonium and sodium bicarbonate solutions are basic, as the anion $\ce{HCO3-}$ is a stronger base than is the strength of the acid $\ce{NH4+}$, not even talking about $\ce{Na+}$. Carbonic acid ...
Poutnik's user avatar
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3 votes

Is it possible to make acids and bases in amphiprotic solvents other than water

Certainly! There are various definitions for acid and base, such as Brønsted–Lowry, that describe acid/base reactions as the transfer of protons ($\ce{H+}$), without requiring hydroxyl ions ($\ce{OH-}$...
DrMoishe Pippik's user avatar
3 votes

Can pure hydronium exist?

Absolutely, and it's not even difficult. Sure, in the dilute gas phase naked $\ce{H3O+}$ is commonly found simply due to the relative ease of formation and abundance of $\ce{H+}$ and $\ce{H2O}$, in ...
Nicolau Saker Neto's user avatar
3 votes

Why is pH the most commonly known acidity scale when there are more intuitive ones?

This was suggested on April 1st 2019 but did not gain traction. Sometimes, the historical definitions prevail even when there are (with hindsight) better definitions. For instance, learning chemistry ...
Karsten's user avatar
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2 votes
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Why my mineral water from different sources do not mixed well?

The bubbles, floating or not floating, are made of $\ce{CO2}$ which was initially dissolved in one of the mineral waters (physically dissolved or combined as $\ce{HCO3^-}$ ion). By mixing it with a ...
Maurice's user avatar
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2 votes

Why would my pH meter have changed its voltage setpoints?

Electronic components and electrodes are aging and their parameters drifting. Or the pH electrode is off because of its bad conditions. As pH meters are usually also mV meters, check its voltage ...
Poutnik's user avatar
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2 votes

How can the Kw of water be constant?

Dissociation equilibrium in water is attained when the rates of the following forward and reverse reactions are equal (all species aqueous of course): $$\ce{H2O ->[k_f] H+ + OH-} $$ $$\ce{H+ + OH- -...
Buck Thorn's user avatar
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2 votes
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pH calculation of HCOOH +plus HCl solution

In a mixture of two acids, nothing happens : no reaction between the acids. No salt ! At $\ce{pH = 1.5}$, the finall concentration of $\ce{H+}$ is $\ce{10^{-1.5} = 0.0316}$ M. This concentration is ...
Maurice's user avatar
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2 votes

Can pure hydronium exist?

Neutral hydronium may also exist. Huang et al. [1] calculate that $\ce{H3O}$ is stable as a liquid metal phase under high pressure and temperature conditions existing in the interiors of Uranus and ...
Oscar Lanzi's user avatar
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2 votes
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Change in pH/acidity of vinegar after adding aqueous NaCl

Your thoughts are absolutely correct, when being absolutely precise. If one diluted vinegar (5% ethanoic acid) with an equal quantity of plain water or salt water, there certainly would be a ...
DrMoishe Pippik's user avatar
2 votes
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How long can pH solution calibration be used for?

If you want to deviate from the given procedures, you are on your own and you have to experiment and verify. One way is, after the calibration, to save calibration solution(s) to be used as the ...
Poutnik's user avatar
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2 votes

Can I use pH test papers with a dye-rich solution?

There are very cheap handheld pH meters available (for <$30, example) about as or more accurate than indicator paper (which is accurate to ~0.5 pH units) and useful over a wide pH range (precision ...
Buck Thorn's user avatar
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2 votes

How does the concentration of H+ ions in HCl change as the pH changes?

What is the concentration of H+ ions in a solution of hydrochloric acid with pH 2.5? Using the definition of pH $= -\log(\frac{[\ce{H+}]}{\pu{1 mol L-1}})$, you can easily calculate this as long as ...
Karsten's user avatar
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2 votes
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pH at maximum concentration of a certain species (Phosphoric acid)

The fraction of the dyhydrogenphosphate, while ignoring the third ionization, is: $$x(\ce{H2PO4-})=\dfrac{K_\text{a1}\cdot [\ce{H+}]}{[\ce{H+}]^2+K_\text{a1}.[\ce{H+}] + K_\text{a1} \cdot K_\text{a2}}\...
Poutnik's user avatar
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2 votes
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Relative concentrations of ions in pure water with a pH of 7

$\pu{1 L}$ of pure water at $\pu{25 ^{\circ}C}$ contains about $\pu{55.5 mol}$ of water and $\pu{100 nmol}$ (or $\pu{e-7 mol}$) of both $\ce{H+(aq)}$ and $\ce{OH^-(aq)}$ ions. Therefore, the ratios ...
Poutnik's user avatar
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2 votes
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Why should the pH change when I add sodium hydroxide to water?

Water can be thought of as a dissociation reaction $$\ce{H2O <-> H+ + OH-}$$ When you add in $\ce{NaOH}$, it dissociates completely into $\ce{Na+}$ and $\ce{OH-}$. This causes the equilibrium of ...
Number Basher's user avatar
1 vote

pH at maximum concentration of a certain species (Phosphoric acid)

Now that you have posted comment to the original question Phosphorsäure hat die folgenden drei pKa-Werte: pKa1 : 2.15 ; pKa2 : 7.20 ; pKa3 : 12.4 i) Bei welchem pH-Wert einer wässrigen ...
ACR's user avatar
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1 vote

How does the concentration of H+ ions in HCl change as the pH changes?

This question changes a simple definition of: [pH = the negative logarithm of the hydrogen ion activity in M/L], into a puzzle or possibly an IQ test. Knowing nothing about pH the relationship between ...
jimchmst's user avatar
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1 vote

Finding the pH level of a liquid process

AFAIK, the universal indicator already contains bromthymol blue. Why to add it explicitly? RGB value is not enough to determine pH due multiple factors. Aside of that, such a measurement is useless, ...
Poutnik's user avatar
  • 42.4k
1 vote

dilution and pH and pOH

If you started with a $\pu{10^{−12.3} M}$ solution of some inert material, then diluting it by a factor of 10 would indeed result in a $\pu{10^{−13.3} M}$ solution. $\ce{H3O+}$ is not inert. It reacts ...
anon's user avatar
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1 vote

dilution and pH and pOH

As Poutnik writes in the comments, the question does not have a single answer unless you specify the components of the solution. Given that the pH is fairly basic at pH = 12.3, you could guess or ...
Karsten's user avatar
  • 40.8k
1 vote
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At 80 °C a solution having pH = 7 is?

The neutral $\pu{pH}$ is half the $\pu{pK}$ value for water dissociation, and of course the latter is almost exactly $14$ at $25°$C and one bar. That's where we get $\pu{pH}=7$ for a neutral solution —...
Oscar Lanzi's user avatar
  • 59.1k
1 vote

How can the Kw of water be constant?

The hydroxide ions will react back indeed, albeit with hydronium ions (not $\ce{H^+}$), but because there are only $10^{-7}$ mol/l hydroxide ions in solution, it can also react with a maximum amount ...
Mäßige's user avatar
  • 265
1 vote

How can the Kw of water be constant?

If you add $\ce{HCl}$ in water, the amount of $\ce{H+}$ increases of course. And part of this supplementary $\ce{H+}$ ions are used to destroy $\ce{OH-}$ ions from pure water. This amount of $\ce{H+}$ ...
Maurice's user avatar
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