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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3answers
11k views

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
288 views

What is the pKa of 2-methyl-2,4-pentanediol?

What is the pKa of 2-methyl-2,4-pentanediol? Is there a reference that contains a list of pKa values for various molecules that I can consult or is there a way to determine/estimate the pKa of this ...
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3answers
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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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1answer
15k views

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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2answers
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What is the importance of using a pKa value instead of a pKb value when describing drug chemistry?

Why do we only consider the $\mathrm{p}K_\text{a}$ value of a drug regardless of whether it is an acid or base? Why do we not use the $\mathrm{p}K_\text{b}$ value?
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Should the 'a' in the acid dissociation constant (Ka or pKa) be capitalised?

In science, the negative logarithm of the acid dissociation constant is denoted $\mathrm{p}K_\mathrm{a}$ or $\mathrm{p}K_\mathrm{A}$ depending on the source (lowercase "a" or uppercase "A"). Since it ...
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1answer
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Why should colorimetric titration of a weak acid with a weak base not be done in laboratory? [closed]

Why should colorimetric titration of weak acid with a weak base (or vice versa) not be done in laboratory? How can I draw a pH graph for this?
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105 views

Isoelectric point pH, mV, for a metal oxide nanopowder

I'm trying to make a solution of $\ce{TiO2}$ that will coat stuff in as dense a monolayer as possible. To do so, I'm using nano sized $\ce{TiO}$ particles and trying to get them to get as close to ...
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1answer
2k views

Why does this shortcut work for calculating pH (proof required)?

My teacher gave me a shortcut regarding calculation of resultant pH if the solutions are mixed and if the difference between the pH of individual solutions is 1. If there are two solutions, the pH is ...
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1answer
99 views

What are the properties of various solutions at pH <2 that may cause injuries?

For example, why do some solutions not cause any injuries at pH 2 while HCl does?
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36k views

pH range outside conventional 0-14 [duplicate]

Is a pH value outside 0 - 14 possible? I asked my teacher who said: yes, it is, but very difficult to achieve. Then on the internet, I found multiple answers, one saying it is but because of a fault ...
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1answer
137 views

Isoelectric pH of colloids?

How did we derive the relation between the isoelectric pH and the dissociation constants for the amino and carboxyl groups on zwitterionic amino acids. $$pI=\frac {pK_{a1}+pK_{a2}}{2}$$ where $$\ce{...
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Teeth friendly alcohol drinks

What is the best alcohol for your teeth according to the pH? Is it true that if the acidity of the drink is higher (and ph is lower) than it's worse for your teeth (enamel erosion + bacteria friendly ...
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Why does water dissociate to H3O+ and OH- rather than H+ and OH-?

Why does water dissociate to $\ce{H_{3}O^{+} + OH^{-}}$ instead of $\ce{H^{+} + OH^{-}}$? This question came to surface when I was learning about acids and bases, and learned this definition: $\...
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1answer
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How to estimate pH?

How you you calculate/estimate the pH of a solution with 3 components all of different pHs? Is there a paper describing this? For example: 0.1M Buffer PCTP at pH 9.5 1.6M Sodium Dihydrogen Phosphate ...
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1answer
15k views

Calculating the pH of a solution of Ca(OH)2

A solution prepared by dissolving $2.8 g$ of lime, $\ce{CaO}$ in enough water to make $1.00 l$ of lime water ($\ce{Ca(OH)_{2(aq)}}$). If solubility of $\ce{Ca(OH)2}$ in water is $1.48 g$. The $p\ce H$ ...
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Does the hydrolysis speed increase when more H+ ions are in the solution?

In hydrolysis of polysaccharides, does the hydrolysis speed increase when more $\ce{H+}$ ions are present in the solution? So if I were to use $\ce{H2SO4}$ instead of $\ce{HCl}$ (same volumes) then $\...
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If the pH is zero, what would be the normality of a sulphuric acid solution?

If pH of the solution is zero, what would be the normality of $250 \, \mathrm{ml}$ $\ce{H2SO4}$ solution? My work: $\mathrm{pH} = 0$, hence the concentration of $\ce{H+}$ ions is $\pu{1 mol L^-1}$, ...
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8answers
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Is a negative pH level physically possible?

A friend of mine was looking over the definition of pH, and wondering if it is possible to have a negative pH level. From the equation below, it certainly seems possible—just have a $1.1$ (or ...
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1answer
122 views

Less maintenance-dependent continuous pH testing

I am creating an automated chemical component mixing system (DIY project). One of the features required is continuous monitoring of pH value in my main solution. I do not need it to be very precise, ...
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3answers
8k views

How do indicators work when they mixed with each other?

Methyl orange, bromothymol blue and phenolphthalein indicators were mixed together to form a solution. Over what pH range would the solution be yellow? I cannot understand the question. If two or ...
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1answer
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Effect of dillution on titration

When we are titrating acid/base using ph meter we add distilled water to immerse the ph electrode. Won't this affect the concentration of the acid/base: I mean isn't this dillution. Won't this ...
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How can I measure the pH of high-viscosity fluids like dough?

I would like to measure the pH value of dough with a pH-Meter, to ensure a pH value of 4.1 (max). Because of the high viscosity I would thin down the dough with demineralized water for two reasons: I ...
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1answer
20k views

The influence of lemon juice & sugar on the ph-value

If I add equal amounts of lemon juice and sugar into water, does the ph-value remain unchanged, as both cancel each other out? This question arose in my head as I learned that pouring milk into ...
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What chemicals are in tap water that gives it a slightly basic pH level

In chemistry, we recently did a lab where we observed the different ways of reading pH of several different substances. We used things such as red cabbage juice, litmus paper, pH paper and a pH probe. ...
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On the scale of stuff with a pH

I am a confused (and somewhat anal retentive) non-chemist who is trying to understand what pH is. I have come to understand it is a measure of acidity, but I have not yet figured out what that means ...
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2answers
665 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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Chemical reasons for choosing Salt Water or Chlorinated pool?

I am currently researching as too which is better for maintaining the chemical balance in a swimming pool. I have obviously tried the standard Google search for ...
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1answer
27k views

How to calculate the pH of a buffer after HCl was added?

A buffer is made from $50~\mathrm{mL}$ of $1.0~\mathrm{M}$ benzoic acid, $K_a = 6.3\cdot10^{-5}$, and $50~\mathrm{mL}$ of $1.0~\mathrm{M}$ sodium benzoate. a) Calculate the pH of this buffer For this ...
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1answer
542 views

Acids / Bases - Need some clarity for final exam [closed]

I'm studying for my final exam, and these are the questions I got wrong on the mid term, could anyone help correct me? I know people are against giving answers for homework, so I must add that is now ...
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1answer
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How do you find the pH of a solution with a known pKa and Molarity?

How do you find the pH of a solution with a known pKa and Molarity?
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646 views

Calculation of partial charges and protonation/deprotonation states depending on pH

What is the best method for calculating partial charges and protonation/deprotonation states of a small molecule such as phenol or caffeine, depending on the pH? For instance, it is well known that ...
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13k views

Can you create a buffer with a strong acid?

So I was wading through several textbooks yesterday reviewing the concepts of buffers. I found them lot more challenging than I used to. One thing in particular disturbed me: The books and internet ...
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3answers
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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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Why isn't water acidic?

The definition of an acid is a compound with a hydrogen cation and a non-metal anion. Water is a hydroxide bonded to a hydrogen atom. This hydroxide has a net negative charge, too, since the negative ...
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2answers
796 views

How can one calculate the pH of a solution?

So, I have 1 litre of acetate buffer, and 0.1 mol of oxonium ions/$\ce{H3O+}$ is added. The task is to calculate the pH of this solution. What I was thinking: $$\ce{CH3COOH + H2O <=> CH3COO- + ...
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Dissolving Organic Tissues [duplicate]

Watching some movie/TV this question came to mind, purely theoretical of course, if one wanted to dissolve a human corpse, like getting rid of a body after killing someone, is it better to use an acid ...
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1answer
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How does the litmus pH indicator work?

I'm wondering about how does the litmus solution work as a pH indicator. And another question: When you put drops of litmus solution into an colorless acid (e.g. $\ce{HCl}$), it turns red. But then ...
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Computation of pH when an acid and base are mixed in solution

I'm doing a basic chemistry course, and we are currently learning how to compute $\text{pH}$ from the acid dissociation constant (using $\left[\text{H}^{+}_{(\text{aq})}\right]=\sqrt{K_{a}\left[\text{...
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1answer
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Fitting titration curve

To simulate the action of gastric $\ce{HCl}$, we have titrated 100 ml of a meal with 0.1 N $\ce{HCl}$. To plot the data, use (R-code) ...
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1answer
319 views

How can I determine the pH of solution?

Could anyone tell me how I would go about calculating the pH of 100.0 mL of 0.100 M $\ce{H2NNH2}$ ($K_\text{b} = 3.0 \times 10^{-6}$). Furthermore, how would this pH change when 20.0 mL of 0.200 M $\...
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1answer
534 views

How useful is the assumption that water doesn't auto-ionize in the following?

Now in the first row of the iCe-table, $[\ce{H3O+}]$ is said to be 0. But water autoionizes to some extent, so it shouldn't really be 0. I accept that, because the pH of this solution is 2.5, the ...
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1answer
267 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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Why are the majority of cleaning solutions basic?

When testing for pH for common household cleaning products, such as dishwasher fluid, I noticed that majority of them tend to be basic? Why is that? Do acid make good cleaning solutions as well?
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1answer
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Determining the pH of an organic solvent

Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $\mathrm{p}...