# Questions tagged [ph]

pH (or the potential of hydrogen) is a scale used to measure how acidic or basic an aqueous solution is.

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### Calculating the pH of buffer solution made of two salts of a polyprotic acid

When we are making a buffer solution by solutions of a weak acid and its salt like $\ce{CH3COOH}$ and $\ce{CH3COONa}$, or by a weak base and its salt like $\ce{NH3}$ and $\ce{NH4Cl}$, we can use the ...
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### Identifying unknown solution with indicators. why is one pKa value ignored and how to treat negatives values?

Three test tubes contain an identical solution of unknown pH. The first one is tested with thymolphthalein and turns colourless The second is tested with a-naphtholphthalein and turns blue ...
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### How to calculate concentrations when dissolving two salts?

Some solid silver bromate was dissolved together with solid silver acetate what would be the highest achievable pH? \begin{align} K_\mathrm{sp}(\ce{AgBrO3}) &= 5.38 \times 10^{-5}\\ K_\mathrm{sp}...
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### Determination of pKb of a mono acidic base

$20$ mL of a weak monoacidic base($\text{BOH}$) requires $12$ mL of $0.3$ M $\text{HCl}$ solution for the equivalence point. During titration, the pH of the base solution was $10$ upon the addition of ...
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### How to calculate pH of solution made of H3PO4 and Na3PO4? [closed]

I am unable to calculate the $\mathrm{pH}$ of a solution made of $\pu{0.1 M}$ $\ce{H3PO4}$ and $\pu{0.05 M}$ $\ce{Na3PO4}$. How to set the approximation and which ions are present at the ...
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### NMR Prediction for compounds at variable pH values

Like the title says, I'm looking for any software package that may be able to simulate a variety of NMR at a variety of different pHs. The majority of the software programs that I've found do not have ...
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### Why proton concentration is divided by 10⁻⁷?

I am reviewing the book Biochemistry Concepts and Connections by Appling, Cahill, and Mathews and I cannot understand why they divide by the hydrogen concentration by $10^{-7}$. Why not just leave it ...
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### How can I preserve chlorophyll for long periods of time?

I'm currently working on a XIX century photographic process called Anthotype. It relies on organic colored substances that fade when exposed to sunlight. For the substances I've tried alcoholic ...
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### pH change with temperature

I understand that the pH of solutions decreases as the temperature increases but is there a reason as to why some solution's pH decreases more than others even if the temperature change is the same?
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### Why does adding salt to water reduce the pH?

I recently heard someone claim that adding table salt to vinegar caused HCl to form which helped them clean coins - clearly not the case - however I thought I'd disprove it by doing an experiment. So ...
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### Why will a strong acid neutralize as much base as a weak acid?

This is a simple concept that I can't seem to understand. Why will a strong acid neutralize as much base as a weak acid, if the acids are of the same volume and concentration? A strong acid will ...
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### Why can't the strength of superacids be measured in water?

I learned about acid strength, that the strength of an acid increases with it's degree of ionization when solvated. So, in water, a strong acid is one where $\ce{[H_3O^+]}$ is large, which is equal to ...
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### Effect of pH on electrolysis

I understand(more or less) that acidification of water helps in the dissociation of water into ions. Acids easily dissociate into ions in aqueous solution. So accordingly the hydrogen from the acid ...
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### Why must a buffer solution contain both a weak acid and a salt solution of its conjugate base?

Doesn’t the weak acid dissociate to produce the conjugate base on its own? I understand that when a strong base is added to the buffer solution, the hydroxide ions will react with the hydrogen ions ...
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### Does the number of H+ ions in solution go up on dilution of a weak acid?

In my textbook, a footnote says: In case of weak acids, on dilution the total number of $\ce{H^{+}}$ ions in solution increases because dissociation of the weak acid increases This didn't make ...
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### Sugar solutions have a neutral pH in themselves, but it makes your body acidic. Why? [closed]

I'm not an expert, but as far as I understood a sugar solution is completely neutral since sugar can't take hydrogen ions out of the water or donate them in. Sugar is a non ionic compound, so it does ...
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Calculate the pH of a mixture of $75\:\mathrm{cm^3}$ of methanoic acid solution of concentration $0.10\:\mathrm{mol\:dm^{-3}}$ and $75\:\mathrm{cm^3}$ of sodium hydroxide solution of concentration $0.... 1answer 2k views ### Dissolving Tylenol Science Experiment - why is it fastest in distilled water? My son has a science experiment for class to dissolve Tylenol (325mg acetaminophen) in 3 different solutions (125 mL volume each): Distilled water Vinegar (1 part white vinegar to 4 parts water) Salt ... 3answers 22k views ### If you add AlCl3 to water, why does the pH decrease? You are not adding any hydrogen ions, so why does the pH of the solution decrease? Thank you in advance. EDIT: I will add the context of my asking this question to clarify some details. This is not ... 1answer 156 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 ... 1answer 242 views ### Optimum pH range for formation of Schiff bases What is the optimum range of pH for the formation of Schiff Bases by the addition of hydroxylamine to an aldehyde or a ketone? According to Peter Sykes' A Guidebook to Mechanisms in Organic Chemistry,... 1answer 37 views ### Regarding acid-base reactions, how does one know when a hydrophobic base substance is fully protonated? When there's a weak base substance (hydrophobic powder), and it needs to be completely protonated by adding an acid (eg: HCl), how does one know when it's completely protonated? Since the powdered ... 0answers 2k views ### Why does saline have a pH of 5.5? I am a physician and administer 0.9% NaCl in water ("normal saline") to patients frequently. The bag says it has a pH of 5.5 (compared to the human body of 7.4). I am asking why the pH is so low. It ... 2answers 2k views ### pH probe bulb - what is happening within the glass? I am trying to understand how the glass bulb of a pH electrode of a pH meter works - the glass bulb itself. Not the reference electrode or the rest of the electrode (HCl, Ag/AgCl wire, etc...), the ... 0answers 53 views ### Seeming discrepancy between pKa and corresponding Ka of methylamine The first entry in PubChem for the$\mathrm pK_\mathrm a$of methylamine is$10.657$at$25\ \mathrm{^\circ C}$. My elementary understanding is that this would be found as the negative log of the$K_\...
I am trying to solve the following exercise: What volume of a concentrated $\ce{HCl}$ solution, which is $36.0\%$ $\ce{HCl}$ by mass and has a density of $1.179~\mathrm{g~mL^{-1}}$, should be ...