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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Chemical environment that dissolves Hematite and or Magnetite [closed]
I believe it is possible to dissolve Magnetite and or Hematite in a very acidic solution. If all the oxygen was removed. Possibly by bubbling carbon dioxide through the solution would this change ...
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Buffer solution calculations [closed]
calculate the pOH of a solution prepared by dissolving 0.250mol of benzoic acid(C7H5O2H) and 0.150mol
of sodium benzoate in water sufficient to yield 1.0L of solution after addition of 0.005mol of ...
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0answers
38 views
Is contribution to pH by an acid or base always greater than salt hydrolysis?
I was solving a titration question and the reaction I came to was this:
$$
\begin{array}{lcccc}
\ce{&BOH(aq) &+ &HCl(aq) -> &BC(aq) &+ &H2O(l) }\\
\text{Initial} & x &...
-1
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1answer
26 views
What happens when ionic stregth is pretty high in a colloidal system [closed]
I have seen that most of the behaviors on colloidal systems with high salt concentration tend to have lower zeta potentials. But I do not understand why some zeta potential plots in the acidic region ...
1
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0answers
30 views
How to clean pocket pH meter before storage?
Hello.
I read about different methods how to clean this specific(attached photo)pocket pH meter before storage and i can't figure out what is the right way.
One method says to stir the pH meter(...
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2answers
39 views
Can I make a buffer with a weak acid without adding it's conjugated base, when the desired pH of the solution is exactly the pKa of the weak acid?
An acid will be 50% dissociated when the solution it's in have a pH equal to the acid pKa ('afirmation 1', for later reference).
We also know that a good buffer solution have equal concentrations of ...
5
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1answer
77 views
pKa of phenols using UV-Vis spectroscopy
I have done an experiment where I dissolved four different substituted phenols in acidic, basic, and buffer solutions, and recorded the UV-Vis spectra for each. I'm supposed to pick a wavelength where ...
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0answers
60 views
What is the pH and pKa relationship of LaCl3 in water and its precipitant La(OH)3?
In light of this question and its answers, I hope to get some insights into the $\mathrm{pH}$ of $\ce{LaCl3}$ in water and its $\mathrm{pH}$ relationship to $\ce{La(OH)3}$ precipitant's $\mathrm{p}K_\...
2
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1answer
72 views
How to calculate the number of protons in a sphere given the volume and the pH?
The spherical radius of a nano-droplet of a solution ($\mathrm{pH}$ of which is $6$) is given as $\pu{20nm}$.
I can find the molar concentration of $\ce{H+}$ and subsequently the number of $\ce{H+}$ ...
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46 views
Hydronium ion concentration to compare pH values
I'm having a bit of trouble with this question:
Which has a higher $\mathrm{pH}$ value, $\pu{0.001 M}$ $\ce{HCl}$ or $\pu{0.1 M}$ $\ce{CH3COOH}$ $(K_\mathrm{a} = \pu{1.8E-5})?$
I have calculated ...
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How to calculate Revelle factor using only pH, DIC and TAlk for seawater?
I have the temperature, salinity, $\mathrm{pH},$ dissolved inorganic carbon (DIC) and total alkalinity (TAlk) values for an estuarine water sample. I want to calculate the Revelle factor.
The Revelle ...
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0answers
24 views
Calculating pH of a saturated weak acid/base solution [closed]
How can you calculate the $\mathrm{pH}$ if you know for example the $\mathrm{p}K_\mathrm{a}$ or $\mathrm{p}K_\mathrm{b}$ value of a weak acid/base and how much acid/base can dilute in water. Let's ...
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1answer
110 views
Is black tea a pH indicator?
Today, I made a cup of lemon tea in a different way than usual. Instead of pouring hot water in to a mug containing lemon juice and black tea (my normal routine), I let the tea steep for a little ...
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2answers
70 views
Finding pH of acid in water [closed]
How would you find the pH of an acid dissolved in water? Would you need to take the fact that the pH of water is already 7 into account and go on from there?
Say, for example, that you add 0.0500 mL ...
1
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1answer
59 views
Why CO2 is not reducing the pH of NaOH as the way it is expected
I am using $\ce{CO2}$ for the reduction of pH of $\ce{NaOH}$ solution ($\pu{2.5g}\; \ce{NaOH} + \pu{250ml}\; \ce{H2O}$, with $\mathrm{pH}\; 13+$).
I am introducing $\ce{CO2}$ with different dosages ($\...
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1answer
115 views
Preparation of acetate buffer from sodium acetate and hydrochloric acid
A $\pu{1.0 L}$ buffer solution of $\mathrm{pH}~4.43$ is made up of $\pu{0.30 M}$ sodium ethanoate and $\pu{0.20 M}$ $\ce{HCl}$ solutions. Calculate the volume of sodium ethanoate and $\pu{0.20 M}$ $\...
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Is pH in a charged hydrogel and its supernatant solution constant?
Let us assume we deal with ideal systems without interactions.
The gel phase and the supernatant solution phase are in thermodynamic equilibrium. The supernatant solution shall consist of different ...
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0answers
70 views
Can a universal indicator turn colorless?
I learned that litmus paper could be bleached by chlorine to turn colorless. I’m wondering if any chemical substances can react with all the components of a universal indicator such that it turns ...
2
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1answer
68 views
Ratio of uncharged to charged side chains [closed]
The $\mathrm{p}K_\mathrm{a}$ of the side chain imidazole group of histidine is $6.0.$ What is the ratio of uncharged to charged side chains at $\mathrm{pH}~7?$
Here's my attempt to the solution:
$$7 ...
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0answers
39 views
How do I find pH of a mixture of weak acids? [duplicate]
Suppose that we are given two weak bases $\ce{HA_1}$ and $\ce{HA_2}$. We are also given the $K_\ce{HA_1}$ and $K_\ce{HA_2}$. How can we calculate the $\mathrm{pH}$ of the mixture?
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1answer
268 views
How do I calculate the ensemble-average net charge of an amino acid at given pH?
I am given an amino acid with an ionizable side chain at a certain pH. How do I determine the net charge of that amino acid when there are mixed protonation states of one or more of the groups at that ...
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0answers
100 views
Calculating ionic strength and pH of a buffer solution [closed]
Im trying to calculate ion strength and pH of solution.
Components of the solution:
47 ul of 1000 pmol DNA in Elution Buffer (10 mM Tris-HCl pH 8.5) was bound to 3 ul of 10 µM YoYo1 (flourescent dye) ...
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1answer
38 views
How can I prepare two phosphate buffer of different concentrations but give same pH? [closed]
How is it that buffers of different compositions can have the same pH? For example, it is possible to prepare 0.01 M phosphate buffer of pH 7.0 and 0.1 M phosphate buffer of pH 7.0? How?
I used ...
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1answer
63 views
Why can Neutral Red (indicator) not test values below its pKa?
It is the only indicator I have found that does not test below its pka, and can't think of any reason for this.
Neutral Red has a pKa value of 6.8.
(
Reference 1,
Reference 2
),
but looking at its pH ...
1
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1answer
51 views
How a titration curve is affected when a poorly soluble salt is formed?
Suppose that I have $\pu{100 mL}$ solution of strong acid, $\ce{HA}$, at $\pu{0.10 mol L^{-1}}$.
This solution is titrated with a strong base solution, $\ce{BOH}$, at $\pu{0.10 mol L^{-1}}$.
Suppose ...
2
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0answers
21 views
How to control pH in a fermenter based on the acid produced by mircoorganism
I have got a bioreactor with an aqueous medium which produces biomass (yeast; S.cerevisiae) after inoculation.
I am observing and collecting data over the whole process via probes/etc. on different ...
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2answers
61 views
Finding the pH of the solution
In this video, at 3:30 min professor solves two equations
$$\ce{H2O —> H+ + OH-}$$
and
$$ \ce{HCl —> H+ + Cl-}$$
and deduces $[\ce{H+}] = [\ce{Cl-}] +[\ce{OH-}]$. How come this happen from ...
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pKa values for amino acid
To calculate the pI value, we take the average of the pKa values from the 2 groups that result in a net charge of 0.
For that to happen, the pKa values should be at the midpoint of titration where ...
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1answer
41 views
How to predict whether a salt will act as an acid or as a base in aqueous medium? [closed]
How to would we know if a salt such as $\ce{CO_2}$ reacts acidic or basic in water.
The explanation I see everywhere is that you have to see the acid and base that makes up the salt, in the case of $\...
1
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1answer
31 views
The time-dependent pH value in a fermentation
I want to know if someone has supporting tips or solutions to my problem:
In biotechnology, fermentations are used to grow microorganisms. These need a specific media/broth in which temperature, pH, ...
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1answer
101 views
How does sodium carbonate reduce pH?
Sodium carbonate is used in pools to raise pH. From my understanding, it would dissociate in water like so:
$$\ce{Na2CO3 <=> 2 Na+ + CO3^2-}$$
To raise pH, doesn't it have to absorb hydrogen ...
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0answers
39 views
Effects of gamma irradiation on pH buffer
Does anybody know if it is possible to gamma-irradiate a bottle of pH buffer to sterilise it? Are there any known effects (short-term or long-term) of the irradition process on the pH qualities of the ...
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55 views
What is the pH of a solution of iron acetate?
What is the pH of a $\ce{0.1 M}$ solution of $\ce{Fe(CH_3COO)_3}$? I'm not sure how to do this, as it would involve complicated mass balance equations, but I think I can apply the approximation $\ce{...
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1answer
45 views
Acid solution — lower pH when diluted
Today I came across a "thought experiment" regarding $\mathrm{pH}$ of a diluted acid solution. This idea looks somewhat logical but obviously contradicts the reality. Can you show me where is the ...
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3answers
67 views
Doubt on process to calculate pKa [closed]
I have to solve an exercise that I've been trying for a long time without success.
Information that I have:
pH @ certain temperature of an aqueous dissolution of an acid
molar concentration ...
1
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1answer
70 views
Titration of barium(II) hydroxide by hydrochloric acid
$\pu{25 ml}$ of $\pu{0.024 M}$ $\ce{HCl}$ is titrated into a volumetric flask which initially contains $\pu{45 ml}$ of $\pu{0.034 M}$ $\ce{Ba(OH)2}$. Calculate the $\mathrm{pH}$.
This is how I ...
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2answers
80 views
Calculating amount of base needed to achieve a specific pH in a mixed ethanol-water solvent
I'm looking for some way to calculate how much base I will need to add to an unbuffered solvent consisting of a mixture of ethanol and water in order to basify it to a specific reading (10) on an a pH ...
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0answers
47 views
Why might litmus paper and universal indicator give conflicting pH readings in an acid-carbonate reaction?
The resulting neutralised (which wasn't actually neutralised due to not realising CaCO3's insolubility) solution between Hydrochloric Acid and Calcium Carbonate, as per balanced equation
CaCO₃ + 2HCl ...
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1answer
32 views
Acid/Base Indicator [closed]
I'm not sure how the concept and math work on this problem. Can someone show me how you can get the answer, both conceptually and using math?
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1answer
27 views
Calculating the pH of Strong Acid Solutions [closed]
Calculate the $\mathrm{pH}$ of a $\pu{1.5e–11 M}$ solution of $\ce{HCl}.$ How is the $\mathrm{pH}~7?$
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1answer
154 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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What is the cause for the difference in pH between NaCl and Ringer Lactate
Reading this article, I came across a passage which got me to think of this question:
"Normal saline contains approximately $\pu{154mM}$ of each $\ce{Na+}$ and $\ce{Cl-}$ with average pH of 5.0 and ...
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0answers
30 views
Acid and base separation on an anion exchange column [closed]
I'm new with this concept and so I would need some advice.
I want to separate an acid and a base in a water solution. The acid has $\mathrm{p}K_\mathrm{a}(\ce{HA}) = 5$ and the corresponding acid of ...
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0answers
62 views
Calculate the pH
Calculate the pH of a dissolution of 100 ml of 0.1 M solution of ammonium chloride in the style of 100 ml of 0.1 M hydrochloric acid solution
$\ce{NH4Cl -> NH4+ + Cl-}$
$\ce{HCl -> H+ + Cl-}$
...
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0answers
66 views
How does a pH glass electrode work?
Every source I read mentions the potential difference building up at the glass membrane (according to the Nernst equation). But how is this difference actually measured? Sticking an electrode into a ...
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1answer
169 views
Calculating pH when weak base is added to an strong acid
$\ce{NH3}$ solution of $\pu{0.1 mol dm-3}$ is being added to a $\pu{25.0 cm3}$ of $\pu{0.1 mol dm-3}$ $\ce{HCl}$ solution. Calculate the pH of the solution when volume of added $\ce{NH3}$ solution is $...
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1answer
85 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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1answer
56 views
Will strong concentrated acid destroy litmus paper and pH paper if they are dipped in acid?
I am curious to know what will happen if I have litmus paper and pH paper, and I dip them into strong concentrated acid like conc. $\ce{H2SO4}$ to test its acidity or basicity. Will acid destroy ...
2
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1answer
98 views
Confusion regarding calculating the pH of a salt of weak acid and weak base
I need to calculate the $\mathrm{pH}$ of a salt of weak acid and weak base in an aqueous solution.
Method I used for calculation
For a salt of weak acid and weak base (assuming complete dissociation ...
1
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0answers
54 views
Can Acids have pH of more than 7? [duplicate]
Consider a solution of $\text{HCl}$ with a concentration of $10^{-10}$ $\text{M}$. Now, if I find it's pH:
$$\text{pH} = -\log([\text{H}^+])$$
$$\text{pH} = -\log(10^{-10}) = 10$$
At room temperature, ...
