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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Why is the pH of this ammonia solution more acidic than another ammonia solution?

I made two similar ammonia solutions in different ways, and they resulted in different pH, but i'm not sure why. Solution 1 Added 5.84 g NaCl to a 500 mL flask. Then added 10 mL 25% ammonia solution. ...
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comparing basic strength of toluidine isomers [duplicate]

I would like to compare the basicity of ortho and para isomers of toluidine.After comparing the pKb values online the order of basic strength is: p—toluidine> m—toluidine> aniline> o—...
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How do I quantify the carbonate system and its pH speciation?

I did Environmental Water Chemistry as part of my undergraduate course where we quantified pH-speciation for the full carbonate system and I got it right according to my tutor. My speciation profile ...
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Is there any way to measure or otherwise quantify the extent of caramelization experimentally?

I've been trying to design an experiment where I want to compare the efficacy of caramelization of a monosaccharide under different pH conditions (the sugar would be placed in buffers of varying pH). ...
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Basification of Copper Sulfate by the use of only the smallest amount of NaOH [duplicate]

I want to basify copper sulfate (50ml) that has a pH of 3.50 to 5. What's the best way I can do it by using the smallest quantity of reagent. I used NaOh with a concentration of 2 mol/dm^3. Still, I ...
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How the optical fibre pH microsensors work?

Just browsed through the chemical sensor products of the company, called PreSens (https://www.presens.de/products/ph/sensors) in order to look for a precise method to measure pH change in a ...
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Zwitterionic Form in Amino Acid

In my laboratory workbook, it has been mentioned that the zwitterionic form of the amino acid is the dominant form of the amino acid at pI and no movement of the molecules takes place under an ...
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Continuous measurement of urea concentration in water

My colleague and I are working with fertilizers, and we are trying to continuously measure the concentration of urea in water (In situ concentration as function of time). There are two condition that ...
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pH calculation of a mixure containing 2 strong acids and a buffer mixture

Calculate the pH of a mixtureof 10 mL 0,1 M HCl ; 5 mL 0,1 M HNO3 ; 10 mL 0,2 M HAc ; 15 mL 0,4 M NaAc. My understanding was that I have to find the [H+] by: finding the concentration of the products ...
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What is Dornic acidity and how to measure it?

Context: I work with dairy product (cheese making) and in order to improve the quality of my process, I have documentation (in French) which refers to Dornic acidity over time. This graph represents ...
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Do azaindoles primarily exist in anionic form at physiological pH and act as bases?

I am reading an article where they describe azaindoles (bicyclic pyridine/pyrrole rings) as being basic with $\mathrm{p}K_\mathrm{a} \approx 4.6.$ I suppose at physiological $\mathrm{pH}$ and after ...
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Why is PCl3 acidic? [closed]

Why is it that when adding PCl3 into distilled water, the solution becomes acidic? What exactly is the reaction occurring? Must it not be neutral as the PCl3 is molecular, or then P has a lone pair of ...
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How useful is thymol blue (acid) as an indicator?

The pH range of thymol blue (acid) is 1.2-2.8.. This pH range seems pretty useless. Generally, the sudden change in pH for SA-SB titration occurs in the range of 4-10; the sudden change in pH for SA-...
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How to find pH for acetate buffer?

Calculate the pH of the solution that results when $\pu{40.0 mL}$ of $\pu{0.100 M}$ $\ce{CH3COOH}$ is mixed with $\pu{30.0 mL}$ of $\pu{0.200 M}$ $\ce{NaCH3COO}.$ $K_\mathrm{a}(\ce{CH3COOH}) = \pu{1....
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In acids why does polarising the O-H bond weaken rather than strengthen it?

In hexaaquaions it is generally true that aqueous solutions of complex ions with a higher positive charge on the central metal ion will have a lower pH. Explanations typically note that the greater ...
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Lye from human ashes?

I have a friend who requested to be cremated when they died and their ashes planted with a tree. I am a bit concerned that the ashes will not be good for the health of the tree. Will ashes from human ...
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What is the pKa of the O-17 hydronium ion?

At low concentrations of a conjugate acid/base pair in aqueous solutions, the Henderson-Hasselbalch equation gives a good approximation of the ratio of acid and base: $$ \frac{[\ce{A-}]}{[\ce{AH}]} = ...
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Discrepancies in using pOH vs pH to solve H+/OH- concentration change problem

I found an extremely confusing problem in one of the problems we did in class for general chemistry. This was the question: How many moles of $\ce{H3O+}$ or $\ce{OH-}$ must you add per liter of $\ce{...
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How much calcium hydroxide is needed to raise the pH of an aqueous sulphuric acid solution?

Lets say dissociation constants $K_{\mathrm{a}1}$ & $K_{\mathrm{a}2}$ of $\ce{H_2SO_4}$ in water are $1000$ and $0.012$ respectively. So the first dissociation step happens completely: $$\ce{ ...
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Why don't universal indicator solutions react with themselves?

Universal indicator is a pH indicator made of a solution of water, 1-propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, sodium bisulfite, and thymol blue that exhibits ...
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How does pH affect an extraction problem

I am not sure how to understand when pH will affect a given problem regarding extraction. For example, in a problem given that K$_D$ of the reaction is $1.86$ I am asked to calculate: (a) How much ...
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Calculate pH of imidazole in solution

I am having trouble understanding how to know how a molecule will reaction in solution. For example, if I have $\pu{1 M}$ of imidazole in solution, how can I calculate the pH of the solution by only ...
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Why is there an increase in the pH at the start of a titration between a weak acid and a strong base?

Why is there an increase in the pH at the start of a titration between a weak acid and a strong base even though there is acid already present to neutralize it? My intuition says that there should not ...
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How to determine the amount of CO2 sodium hydroxide absorbs?

I first created a solution of $\ce{NaOH}$ and water, 5g of $\ce{NaOH}$, and 100ml of water, with a pH of around 14. I then added $\ce{CO2}$ (mixing baking soda, citric acid, and water) to the solution....
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How to calculate pH resulting from dissolving a salt in water? [closed]

The main question is how to calculate the changes in pH after dissolving a salt in water. Suppose we dissolve 1 gram of magnesium carbonate (MgCO3) in 1 liter of Water. This will result in (...
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Finding dissolved amount of base from pH and solubility product

Calculate the amount of $\ce{Mg(OH)2}$ which is solubilized in $\pu{1.25 L}$ of a buffered solution at $\mathrm{pH} = 9.5$. $(K_\mathrm{sp}(\ce{Mg(OH)2}) = \pu{5.61E-12})$. From $\mathrm{pH}$ I ...
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pH of water on paper vs meter

We have both a professional (lab) pH meter, and several different version of lab grade pH paper, but are experiencing a very weird phenomenon. We have calibrated all the papers against standards, and ...
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Can addition of a "neutral" salt like NaCl assist pH test strip measurement accuracy in low ionic strength/poorly buffered solutions?

After a web-search, it seems ISAs (Ionic Strength Adjusters) are offered commercially to assist pH electrode/probe measurements. Presumably meant to increase conductivity (without affecting pH ...
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Using a pH meter to measure the presence of water in liquid ammonia? [closed]

I intend to do some experiments with building an ammonia-water gas adsorption refrigerator similar to a Crosley Icyball Wikipedia - Icyball. When recharging the icyball, it is important to not ...
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How to estimate the pH of multi-component buffer (phosphate buffer in equilibrium with CO2 rich atmosphere)?

I wonder how the pH of buffer solution can be estimated if buffer consists of several systems in equilibrium to the gas phase. For example, (based on growth medium for one of the bacteria) buffer ...
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Comparing acidity between 4-hydroxybenzaldehyde and 2-hydroxybenzaldehyde

https://hmdb.ca/metabolites/HMDB0011718 https://hmdb.ca/metabolites/HMDB0034170 The above two links provide the pKa values for the 4-hydroxybenzaldehyde (pKa = 7.32) and 2-hydroxybenzaldehyde (pKa = 8....
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Will concentration of sodium hydroxide affect the result of chicken feather hydrolyzate if i don't standardized it?

The title of the paper: Isolation and characterization of keratin from chicken feathers https://doi.org/10.1063/5.0002792 Here is the method: Keratin was isolated by dissolving 5g of chicken feather ...
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How is MgSO4 a neutral salt? [duplicate]

So the reaction for forming MgSO4 involves two reactants: H2SO4 and Mg(OH)2, However, the salt formed is netural. Even though H2SO4 is a strong acid and Mg(OH)2 is not a strong base. Shouldn't the ...
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2 answers
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Why are almost all fruits acidic? [closed]

Almost all the fruits are acidic in nature, but why? At least, fruits like apples should be neutral right? But although apple is sweet, it is acidic. Why?
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How to compute a needed volume of solution to adjust to a target pH

I am a software engineer and I would like to solve a chemistry problem. I have revised the subject a bit to understand the basics :) My goal is to maintain a constant pH of a water tank (tap water). I ...
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What might cause overestimated measured pH value of sodium hydroxide solution pumped with carbon dioxide?

I tried an experiment at home where I had a $\ce{CO2}$ tank pumping $\ce{CO2}$ into a solution of $\pu{28 g}$ sodium hydroxide in $\pu{200 ml}$ water. The initial $\mathrm{pH}$ was $11.24.$ I expected ...
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3 votes
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If a carbonic acid to bicarbonate reaction involves the release of H+, why does pH increase? [closed]

OK, I'm an engineer that took Aqueous Geochem 6 years ago, so please forgive this basic (get it?) question. But why do the two reactions which start from dissolution of CO2 in water increase pH if ...
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12 votes
1 answer
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Why measure both alkalinity and pH in pools if pH alone tells us how acidic or basic something is?

I am trying to better understand the chemistry of maintaining my pool so that I can use the least amount of chemicals to control algae growth and I'm confused by the need to measure both total ...
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Understanding weak acid-strong base titration

Today I stumbled across a website which defined the titration of weak acid and strong base as the following: "The titration of a weak acid with a strong base involves the direct transfer of ...
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2 votes
2 answers
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Efficacy of Intramolecular Friedel-Crafts reaction on =o, c=o bonds of ring structures?

Updated Q: Inquiring to understand the efficacy of intramolecular Friedel-Craft like reaction on stability on the ring structures with =o, c=o bonds. Keen to know if ring structures are challenged ...
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pH of PBS after adding acetic acid

Why is there a need for pH adjustment below ? Can pH go below 4.3 after adding acetic acid to PBS ? “First prepare stock solution consisting of 50 ml of 10× PBS (pH 7.4), 12.5 ml of 80% glycerol, and ...
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Approximation for pH calculation with diluted acids in weak-strong titration curve

I was wondering how one could calculate small pH changes in titrations with dilute acids. As we know, usually we approximate the pH by saying that the conversion is quantitative. For example, when we ...
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DEG monobutyl ether pH change

We are using DEG monobutyl ether (CAS 112-34-5) in our production. Normally it is pH neutral, however suddenly we noticed that it has shifted to being acidic (pH=3.4). What has changed in the material?...
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Why are colloidal sol particles of acidic dyes negatively charged and basic dyes positively charged, when it should be the other way round?

From NCERT Class 12 Chemistry; Sri Aurobindo Marg, New Delhi, India; January 2019; p. 136: Colloidal solutions of basic dyes like methylene blue are positively charged whereas colloidal solutions of ...
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Do solid phase pH buffers exist?

I want to buffer the pH of my solution but I don’t want to add any mobile solutes. I imagine that large molecular mass buffers could be used such as phosphorylated polysaccharides or proteins. The ...
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3 votes
1 answer
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What is the pH of the universal indicator?

I know that the universal indicator is a solution of various pH indicators used to find out the pH of a substance by displaying different colors. But, what is the pH of the universal indicator itself? ...
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1 answer
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Prepairing a Sodium Acetate buffer - Meaning of molarity

We have instructions to prepare a "50 mM Sodium Acetate, pH 5 solution". I am not entirely sure what does the molarity refer to in this case. Does it mean: Add Sodium Acetate salt up to 50 ...
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Chlorophyll content in relation to the pH of the solution in which it is boiled

What would be the expected trend of chlorophyll content in relation to the pH of the solution in which it is boiled? Would there be the least chlorophyll degradation in basic or neutral solutions? ...
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Adding H2O2 in water does what to the pH of the water?

Not looking for numbers (unless required). I searched for this question on Google and found irrelevant results, with only the following link of some use but it doesn't appear to answer my question (...
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How do two species from the same buffer system have different pKa values? [closed]

$$ \begin{array}{lr} \hline \text{Reagent}~(\pu{0.1 M}~\text{solutions}) & \mathrm{p}K_\mathrm{a} \\ \hline \text{Ammonia} & 9.25 \\ \text{Acetic acid} & 4.75 \\ \text{Ammonium chloride} &...
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