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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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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Why does pH change with temperature? [duplicate]

Why does pH change with temperature? I recently read up on some chemistry notes, and found out that the higher the temperature of distilled water, the lower the pH. Why? Does this apply to other ...
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What pH indicators are commonly used for non-polar medium?

Compounds, commonly used as pH-indicators, are soluble in aqueous media and polar solvents (DMSO, DMF, NMP etc.) and are functional pretty much across all these solvents. However, practically none ...
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Help with idea for an optical ph sensor

I am experimenting at home with the idea of making an optical ph sensor that can read the colour of ph indicator using photodiodes. I am wondering if there is some kind of ion permeable membrane ...
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1answer
85 views

pH Determination

I have a cubic box of length $L=12.42\ \mathrm{\overset{\circ}A}$, containing $60\ \ce{H2O}$ and $1\ \ce{H+}$ ion. What is the $\mathrm{pH}$ of the system? Following the basic definition, $\mathrm{pH}...
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How much hydrolysis will likely occur of the following bonds at pH 1-4 in the time period of 1-3 hours?

The bonds are: (I have given pictures of what I mean in case there's any ambiguity that I leave open in these questions. Also so that if you want to number the R groups you've got a head-start) ...
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1answer
169 views

Finding concentration and moles given final and initial pH

Questions: How many moles of $\ce{NaOH}$ are needed to change $500~\mathrm{L}$ of solution with $\mathrm{pH}\ 2$ to $\mathrm{pH}\ 11$? A swimming pool contains 2 million litres of water at $\...
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1answer
2k views

Find the concentration of the HCl solution when mixed with 1.265g of ACES-K+

$1.265\ \mathrm g$ of N-(2-acetamido)-2-aminoethanesulfonic acid potassium salt (ACES-K+, $M=220.29\ \mathrm{g/mol}$) is dissolved in $88.42\ \mathrm{mL}$ of water. $27.59\ \mathrm{mL}$ of $\ce{HCl}$ ...
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133 views

Positive charge on a zwitter ion at pH=7?

I faced this question. But I am having some problems understanding the solution to this: How can the negative charge on the peptide vanish on $\pu{pH = 7}$? Suppose, we have some $\ce{H+}$ donor on ...
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How concentrated can an acid be?

How concentrated can an acid be without it being supersaturated? Is there a certain limit to how concentrated an acid or base can be? When I mean concentration, I mean molarity; so how concentrated ...
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How to verify the accuracy of a pH meter

One suggestion I received is that I prepare a solution of a known activity and probe the solution with the pH meter. The problem I see with this is that any error in solution preparation can lead us ...
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Why isn't CH3OH basic if it contains OH?

I was asked to find the most basic solution from the following: $\ce{K2SO4}$ $\ce{CH3OH}$ $\ce{Na2CO3}$ $\ce{(NH4)2CrO4}$ $\ce{BaCl2}$ I know that I have to identify the solution that ...
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195 views

Using non-food grade NaOH for pH control

I would like to use non-food grade $\ce{NaOH}$ for $\ce{pH}$ water treatment. Any problem with this mixing with water that contains iron? The $\ce{NaOH}$ will be pumped into a well. As a $25\%$ ...
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620 views

Why do we neglect the protons from water's autoprotolysis?

Why don't we need to consider the $\ce{H+}$ ions of water when finding the $\ce{pH}$ of $0.01~\mathrm{M}$ of $\ce{HCl}$ solution? The $\ce{pH}$ value of something is depending on the molarity of $\ce{...
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1answer
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Mixing Ca(OH)2 with Ca(NO3)2

Mixing $\ce{Ca(OH)_2}$ with $\pu{0.1 M}$ concentration of $\ce{Ca(NO3)2}$. What will actually happen in the process? What I will see with my eyes? I know that $\ce{Ca^2+}$ cation with concentration ...
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What is the pH of 1M Glycerol?

If the pKa of Glycerol is 14.15. How do you calculate the pH for it? I assume that the Henderson-Hasselbalch derivative that works for weak acids and bases is not applicable here.
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1answer
112 views

The percentage of ingredients in a glass of tea [closed]

When a pot, pitcher, glass, etc of tea is brewed, how do I find the exact concentrations of tea and water in the end result. I realize it depends on the amount tea and water used when brewing. Is it ...
2
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1answer
607 views

Chalcogens' hydrides as acids?

I've noticed that chalcogens never form binary acids, and instead end up like water, with very little acidity. Why is this? Or am I wrong and there's a counterexample, if so please give it.
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Why is buffer capacity at a maximum when the ratio of its components is 1? [duplicate]

A buffer consists of a weak acid and its salt or weak base and its salt. When the ratio of weak acid and its salt in a buffer (or the ration of weak base and its salt) is equal to 1, we say that the ...
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1answer
245 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,...
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107 views

Can I use my extech pH 60 meter to measure soil pH if so how?

Can I use my extech pH60 meter to measure soil pH if so how? I included a link to the meter. Extech pH 60
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Software/server for calculation of protonation states of small molecules depending on pH

For docking calculations at different values of pH, I am working with flavonoids and would like to know about any software/server that can prepare ligands depending on the pH. Up to now I read about ...
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1answer
49 views

Can I use litmus paper to test unknown liquid that contains a concentrated strong acid?

Can I use litmus paper to test unknown liquid that contains a concentrated strong acid (example $\ce{H2SO4}$)? Can concentrated strong acid destroy litmus paper?
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897 views

How do I calculate the pH of this buffered solution?

Calculate the $\mathrm{pH}$ of a buffered solution containing $\pu{0.5 M}$ ammonia and $\pu{0.5 M}$ ammonium chloride when $\pu{0.15 M}$ $\ce{HCl}$ is added into it. The $\mathrm{p}K_\mathrm{b}$ of ...
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399 views

Regarding Kw, titrations, and pH

So I have need of performing a titration upon a fruit juice to determine acid concentration. I will be using 1M NaOH as my base. Seeing as the solution will be coloured, it would be difficult to use ...
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Understanding how to calculate the pH of a buffer with ice tables

Let's say you are asked to calculate the pH of a solution with: $\mathrm{0.1~M}~\ce{HCl}$ $\mathrm{0.2~M}~\ce{CH3COOH}$. $K_\mathrm a = 2\times 10^{-5}$ This is how I would do it: $$\ce{CH3COOH ...
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Acidic and alkaline salt solutions: why do some salt form acid/bases while others don't

I have a question regarding salts and their solutions. How come some salts, like sodium carbonate and ammonium chloride, produce acids/bases when dissolved in water? Moreover, how can you predict ...
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1answer
262 views

How would I neutralize a PEP (Phosphoenolpyruvic) acid?

PEP (Phosphoenolpyruvic acid) is acidic but I need to make it neutral. I need a solution (pH 6-8) of PEP in a final 1 mL volume with a concentration of 100 mM. How would I make this?
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69 views

Why does pH of a buffer solution change according to Henderson–Hasselbalch equation? [closed]

If I add a little amount of acid or base to a buffer solution, the pH of the buffer won't change. That's what the diagramatic mechanism tells us. But according to Henderson–Hasselbalch equation, the $...
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1answer
41 views

Calculating molecular weight of an acid based on given values of mass, volume, pH and pKa

This is what I thought was an easy problem but according to a given answer I am doing it wrong: $\pu{11 mg}$ of a monoprotic acid was dissolved in $\pu{0.5 l}$ of water. The resulting $\mathrm{pH}$ ...
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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 ...
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1answer
197 views

Why does slaked lime water lose alkalinity over time?

When I throw 3 handfuls of white lime $\ce{Ca(OH)_2}$ into 60 gallons of tap water, the initial pH value is 11.4, but unknowingly it changes to pH 7. What is the chemistry behind it? How long does ...
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1answer
152 views

Bleach in drain cleaners

I have a clogged pipe in my bathroom so I went to the store to get something to unclog it. Basically there are two types that you can find in my area: Sodium hydroxide pellets "Liquid plumber" ...
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1answer
1k views

How to get specific concentration of carbonic acid in solution?

I wanted to know if there is a way of getting specific quantities of carbonic acid? Carbonic acid is water + $\ce{CO2}$ but not all the $\ce{CO2}$ dissolves in water. So if I wanted $5\:\mathrm{g}$ of ...
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4k views

Titration curve of a diprotic acid with a strong base titrant

I have wonders regarding the titration curve of the titration of sulphuric acid, or any diprotic acid, with a strong base. I am aware of the fact that a diprotic acid is protolysed in two steps but, ...
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1answer
7k views

How to determine and derive the protonation state of a functional group based on its pKa?

In our biochemistry class we were introduced to a rule of thumb, which goes something like this: "If the pH of a solution is one or more units below the $\mathrm{p}K_\mathrm{a}$ of a group, then ...
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1answer
784 views

Potentiometric titration using a pH meter

Why is the pH of a buffer solution measured before measuring the pH of an unknown solution? I do not have any idea about it. I had read a chapter about ionic equilibrium and electrochemistry, but have ...
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1answer
1k views

What is the pH of CsBr?

What is the pH of CsBr? 3.8 7 9 12 According to me, $\ce{Cs+ + H2O <<=> CsOH + H+}$ (because $\ce{CsOH}$ is a strong base, the forward reaction should not occur, right?) ...
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Finding new pH after NaOH added to buffer solution

I have a buffer containing 0.2 M of the acid $\ce{HA}$, and 0.15 M of its conjugate base $\ce{A-}$, with a pH of 3.35. I need to find the pH after 0.0015 mol of $\ce{NaOH}$ is added to 0.5 L of the ...
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What ratio of bicarb to vinegar do I need in order for the result to be pH neutral?

This question stems from one I just asked over at Seasoned Advice, where my recipe tasted decidedly off because the pH was wrong. The recipe called for $\pu{16 g}$ bicarb of soda (sodium bicarbonate, ...
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1answer
127 views

Adding water on CH₃COONa. What's the new pH?

We have $10 \,\mathrm{L}$ of solution of $\ce{CH_3COONa}$ with concentration $C=1\,\mathrm{M}$ and $\mathrm{pH}=10$. Then we ad $90\,\mathrm{L} \space \ce{H_2O}$. The question is what will be the pH ...
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1answer
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Calculating approximate pH of polyprotic acids

When I took up ionic equilibria and titrations after a long break, I found it hard to solve the questions regarding pH calculations of polyprotic acds. Consider these two questions as examples:- ...
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1answer
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At what acid concentration does potassium metabisulfite react?

I'm in the process of developing a well preserved food-stuff containing potassium metabisulfite and a number of acids (acetic, ascorbic, malic, tartaric, citric, lactic). Wine-making literature ...
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1answer
127 views

Determining the reduction potential of a half cell reaction at a given pH

$E^\circ_\ce{Cu^2+|Cu} = \pu{0.34 V}$. What will be reduction potential at $\mathrm{pH} = 14$ for the same couple? Given that $K_\mathrm{sp}$ of $\ce{Cu(OH)2}$ is $10^{-19}$. My Attempt I think ...
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1answer
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What are standard controllers for automatic pH control?

My background in control theory comes from electrical engineering (robots, motors, etc.) and I want to build a control system for automatic pH control. Can I directly apply my knowledge from ...
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1answer
475 views

Why was my soap measured as acidic?

I've always been told soap is basic in pH. A few years back in a high school chemistry class, we measured the pH of various substances with universal pH indicator. We measured some liquid hand soap ...
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1answer
55 views

Formation of silica from TEOS

Usually tetraethyl orthosilicate/tetraethoxy silane (TEOS) is mixed with both ethanol and water to produce silica in a sol-gel process. I am curious what happens if one adds TEOS to water at a high pH,...
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1answer
259 views

How to know the aluminium sulfate solubility as function of the pH?

I'm trying to find a diagram or a reference for to know the solubility of aluminium sulfate $\mathrm{Al_{2}(SO_{4})_{3}}$ in differents pH values. Something like:
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1answer
361 views

In the graph provided, which of the substances is the most efficient in acting as an antacid?

If every dot represents the addition of 0.1 g of the respective base. I suppose that the best would be the one that reaches the highest pH, in the shortest time, for example Calcium Carbonate, but if ...
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2answers
348 views

How does the pH of fresh glacial meltwater compare to marine seawater?

How does the pH of fresh glacial meltwater (at the time of melting, so it has not travelled downstream for example) compare to marine seawater? I assume that glacial ice is more neutral since it ...