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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Assessing stability of protein used for interaction experiments after changing buffer from tris to HEPES

I have a protein with a theoretical $\mathrm{pI}~9.0$ currently stored in $\pu{25 mM}$ tris and $\pu{250 mM}$ $\ce{NaCl}$ $(\mathrm{pH}~8)$ at $\pu{−80 °C}.$ I need to do experiments in HEPES at $\...
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Phosphate buffer saline with different pH values [closed]

I would like to know with which reagent we can decrease the pH of the potassium phosphate buffer saline?
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How does the concentration of H+ ions in HCl change as the pH changes? [closed]

I am helping my friend's 16 year old prepare for her GCSE chemistry exam. This question was on an AQA GCSE Chemistry past paper but I do not know the year and could not find a markscheme for it on the ...
Judith Jones's user avatar
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What effect does the weak base have here?

Suppose we reacted enough strong base to fully neutralise a weak acid, clearly at this point (the equivalence point) the $pH$ would not be $7$. This is because the reaction between the strong base and ...
nav's user avatar
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Hydrolysis of $A_3B$ type weak acid-weak base salt

I know the formulae for weak acid-weak base salt of AB type. A peculiar question made me ask this. Do the formula for derived for AB type also hold for A3B type sal. For example: This is the question, ...
Aurelius's user avatar
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Proper batch adsorption mechanism for heavy metals

I'm a college student with scope on environmental science, specifically the adsorption of heavy metals in aquatic media. Currently, I suffered from serious issue of batch adsorption mechanism, which ...
Muhammad Ihsan's user avatar
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1 answer
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Change in pH/acidity of vinegar after adding aqueous NaCl

There's a question in my (grade 10) textbook asking to determine what will happen to the pH/acidity of vinegar if a solution of sodium chloride in distilled water is added to it drop by drop. The ...
Abhinav Sood's user avatar
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1 answer
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Find the pH of a solution obtained by mixing 100 ml 0.1m Na3PO4 and 100 ml 0.1 M NaH2PO4. Given that H3PO4: [Κα₁ = 10^-4, Κα₂ = 10^-7, Каз = 10^-11] [closed]

So, my query is that since NaH2PO4 is a weak acid, and Na3PO4 is a basic salt, wouldn't they react? Another theory was that since NaH2PO4 is a weak acid and Na3PO4 is a salt of strong acid and NaH2PO4,...
qwqwqwerty-7's user avatar
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Aquatic chemistry, pH and alkalinity

Hope you can help me with an aquatic chemistry question. I have different types of water of different pH and alkalinity. pH, alkalinity, HCO3 and CO2 concentrations are known. I need to calculate the ...
Nathan's user avatar
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Alternative pH sensing methods?

I am looking for alternative methods to measure the pH of water (swimming pools, tap water, rivers,...) with (ideally) the following properties: Durable: no maintenance or calibration required for 5-...
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Does pH affect the activation energy of decomposition of hydrogen peroxide using iron (III) nitrate solution?

I know that pH can affect the activation energy of the decomposition of hydrogen peroxide when catalase is used, as catalase is an enzyme. However, if I use some nonenzymatic catalysts like iron (III) ...
unmyelinated neuron's user avatar
2 votes
2 answers
86 views

How long can pH solution calibration be used for?

I am using a pH meter regularly (6 to 12 time per week), used mostly for home-food processing (mostly measuring the acidity of whey). The meter requires weekly calibration, which is quite time ...
neydroydrec's user avatar
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1 answer
42 views

Finding the pH level of a liquid process

A photo of 15ml of distilled water accompanied with 3 drops of both universal indicator and bromothymol blue were mixed together and taken (white background was put into the back of the beake). The ...
Jimmy Zeng's user avatar
-2 votes
1 answer
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Mass of gaseous ammonia required to prepare ammonia solution of a given pH

How many grams of gaseous ammonia do you need to make $\pu{200 mL}$ aqueous ammonia solution with $\mathrm{pH} = 11.34?$ As the mole ratio is the same for $\ce{H+}$ and $\ce{NH3},$ $$\ce{NH3 + H+ -&...
Allistor's user avatar
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2 answers
139 views

Can carbonic acid form a salt with pH < 7?

Please read edit before answering Background I am currently studying in 10th grade. This question appeared in my science exam - Which acid does not form an acidic salt? Phosphoric acid Carbonic acid ...
GameTime With Aryan's user avatar
3 votes
1 answer
163 views

Reading and adjusting pH of reverse osmosis water

I grow things for a living and regularly use pH meters + strips to read and adjust the pH of various nutrient and pesticide solutions. Oftentimes, I have a need for nearly naked water with the pH ...
Michael John's user avatar
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How do you calculate the pH range for which one metal precipitates but the other stays in solution?

The problem I have been asked to solve is: $\ce{Cd^2+}$ and $\ce{Fe^2+}$ (starting concentration $\pu{E-3 mol/L}$) should be separated by precipitation using $\ce{H2S}$. Does a pH range exist ...
andrej's user avatar
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Is it possible to make acids and bases in amphiprotic solvents other than water [closed]

In such solvents, could there be chemicals which could donate/accept protons, and if so could their solutions display acidic/basic properties?
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How to calculate the pH of a mixture of an acid with a buffered solution?

Being a physicist by training, having worked in software development for the last 10 years. Having heard my last chemistry lecture 15 years a go I am a bit lost in regards to how one can calculate the ...
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Can a multimeter be used to measure PH?

I would like to feed my garden a solution of water and Trisodium Phosphate (TSP), but I am uncertain of the correct amount of TSP to water ratio. Too acidic or too basic of a solution can harm my ...
user148298's user avatar
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2 answers
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dilution and pH and pOH

The question is: given a $10$ ml solution with pH = $12.3$, which is then diluted to a $100$ ml solution, find the pH of the new solution. My attempt was as follows: [H$_3$O$^+$] = $10^{-12.3}$, and $...
Martin Westin's user avatar
3 votes
1 answer
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Are there LCMS compatible buffer systems available for the high pH range 12-14?

I want to perform chemical stability studies for different pH Values. To achieve pH Values from 1 to 6 I can prepare solutions with trifluoric acid and formic acid and ammonium formate and acetate. I ...
raptorlane's user avatar
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1 answer
159 views

At 80°C a solution having pH = 7 is? [closed]

When I came across this question I couldn't understand whether, they are asking the nature of solution at 25°C which has pH = 7 at 80°C or nature of solution at 80°C which has pH = 7 at 25°C ? ...
Rohit P L's user avatar
2 votes
4 answers
162 views

How can the Kw of water be constant?

I know in neutral solution, $\ce{[H+]}= \ce{[OH-]}= \pu{1.0 x 10^-7}$. However, let’s say I add an acid like HCl. This will increase $\ce{[H+]}$, therefore it’s no longer $\pu{1.0 x 10^-7}$, but is ...
Maria's user avatar
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pH calculation of HCOOH +plus HCl solution

Question - What volume of $0.1 \ce{M}$ $\ce{HCl}$ solution should be added to a $\ce{500 mL}$ of $\ce{0.5 M }$ $\ce{HCOOH }$ solution in order to prepare an acid solution of $\text{pH}$ =$1.5.$ $K_a$...
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3 answers
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Can pure hydronium exist?

Can pure hydronium exist? If not, why not? It seems to me (and I am no chemistry expert) like pure hydronium should have the theoretical maximum acidity or minimum pH that a substance can reach. Can't,...
Alexei Rothschild's user avatar
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Dissolution of CO2 over time in a high pH solution

I asked this question in the biology stack-exchange but thought it might be more appropriate here. I am running a batch experiment using penicillin bottles where I have bacteria growing for 21 days in ...
Franco Grosso's user avatar
4 votes
1 answer
577 views

Possible technique for measuring pH in solutions

I would like to develop a device that measures pH in aqueous solutions. I'm not a chemist, but I have some basic knowledge about electrochemistry. So, I thought I could use two electrodes quite close ...
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Why is pH the most commonly known acidity scale when there are more intuitive ones?

Consider the switch from $$\operatorname{pH} = -\log_{10}\left(\left[\ce{H3O+}\right]\right)$$ to $$\operatorname{acidity} = +\log_{10}\left(\frac{\left[\ce{H3O+}\right]}{\left[\ce{OH-}\right]}\right)$...
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1 answer
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Anthoncyanins and its maximum absorbance value

Why does maximum absorbance occur for Anthocyanins at the 500 ~ 600nm range. Additionally how can one explain the high absorbance at lower pH for anthocyanins compared to higher pH values ?
Aurora Borealis's user avatar
2 votes
1 answer
297 views

How to correct for acidic water when taking the pH of a soil/water solution?

I work in a soil science lab and not very much a chemist. Recently I took the $\mathrm{pH}$ of a large number of soil samples using a glass electrode on a mixture of $\pu{10 g}$ soil and $\pu{20 mL}$ ...
Tillandsia123's user avatar
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1 answer
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Creating Chloramines

I'm currently conducting some testing related to indoor pool environments. Here I believe, airborne chloramines are responsible for stress corrosion cracking in austenitic stainless steels. ...
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4 votes
2 answers
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Why would my pH meter have changed its voltage setpoints?

I'm using a Thermo Scientific Orion Dual Star pH/ISE Dual Channel Benchtop Meter. The manual says that a $\mathrm{pH}~7$ buffer should read about $\pu{0 mV},$ and a $\mathrm{pH}~4$ buffer should read ...
Dan's user avatar
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1 answer
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Calculate the pH of a buffered solution after adding strong acid [closed]

Calculate the pH of a solution formed by the addition of $0.0020$ moles of $\ce{HCl}$ to $\pu{100.0 mL}$ of $\pu{0.200 M}$ $\ce{CH3NH2}$/ $\ce{0.100 M CH3NH3Cl}$. $K_\mathrm{b}(\ce{CH3NH2})=4.4\times ...
Shoes's user avatar
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1 answer
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Why my mineral water from different sources do not mixed well? [closed]

Background: In 8 hours range, I have bought cold mineral water (brand A), then refill the plastic bottle with cold mineral water (brand B) from my office. As far i know, brand B has high pH while ...
Yukha Dharmeswara's user avatar
1 vote
0 answers
352 views

Determine the pKa of a diprotic acid by titration (if pKa1 is similar to pKa2)

Determining the acidity constants of a diprotic acid (in my case, tartaric acid) by titration with NaOH and pH-meter is not possible if pKa2 - pKa1 < 2. This is because there are no "pH jumps&...
Stefano's user avatar
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How to calculate pH of a 0.1 M solution of ammonium bicarbonate considering simultaneous equilibrium along with hydrolysis?

We need to calculate the $\ce{[H+]}$ of 0.1M $\ce{(NH4+)(HCO3^-)}$ given the $\ce{k_b(NH4OH), k_{a_1}(H2CO3), k_{a_2}(HCO3^-)}$ The hint tells me to directly use the result $\ce{[H+]=\sqrt{k_{a_1}(\...
Solus's user avatar
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1 vote
2 answers
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pH of a mixture of a weak acid and a different (non-conjugate) weak base

Let's say I have 1000 ml 1 M acetic acid ($\mathrm{p}K_\mathrm{a}$ = 4.76) and add 1000 ml 1M aniline ($\mathrm{p}K_\mathrm{aH}$ = 4.65). To what proportion is aniline protonated? 1M acetic acid has a ...
Lukas4235's user avatar
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1 answer
154 views

Is the common way to calculate the pH of a solution with low concentration of acid wrong? [duplicate]

We had a chemistry test and one of the questions was this: What is the pH of $1,4^{-8} M$ $HCl$ in water? This is such a small amount of acid that you need to take into concideration the self ...
Tuskies's user avatar
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-1 votes
1 answer
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How to find the added volume $V_e$

We have a volume $V_A$ of a solution of $\ce{CH3COOH}$ acid, its molar concentration is $C_A$ and it has $pH_0=3,4$, we add a volume of $V_e$ from distilled water to it, in this case it has $pH_0'=3,7$...
aymen aymen's user avatar
-1 votes
1 answer
65 views

pH of a solution from mixed solution

I am not a chemistry student. I have a problem with my preserved food. I am afraid that the pH is not below 4.6 for it to safe to eat. I want to check the pH of the food but it has small amount of ...
Aji123's user avatar
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1 vote
1 answer
199 views

Henderson-Hasselbalch equation and degree of dissociation

Is it possible to evaluate the degree of dissociation in unbuffered solutions, through the Henderson-Hasselbalch equation? For example: place acetic acid in a sodium hydroxide solution. After the ...
Luckenberg's user avatar
6 votes
1 answer
125 views

How to explain the acidity difference between these β-diketones?

In DMSO, pentane‐2,4‐dione (1) and 1,3‐diphenylpropane‐1,3‐dione (2) possess nearly identical $\mathrm{p}K_\mathrm{a},$ whereas 1‐phenylbutane‐1,3‐dione (3) is almost 1 $\mathrm{p}K_\mathrm{a}$ unit ...
RTChou's user avatar
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1 answer
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pH and degree of dissociation of drugs

I have a doubt, i hope not so stupid. Suppose we consider a buffer solution of acetic acid/acetate at pH = pKa = 4.76 and we add aspirin (pKa = 3.5): given that the pH of the solution is higher than ...
Luckenberg's user avatar
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2 answers
1k views

Influence of (activated) charcoal on water's pH

Does immersing (a) charcoal / (b) activated charcoal (both clean, no ash) into distillate water influences water's pH? If yes - in which direction - acidic or alkaline? If there is an influence - is ...
user1876484's user avatar
0 votes
0 answers
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Dissolution of portlandite, calcite/CaCo3 phase and C-S-H due to high pH

I would like to ask about the possibility of the partial dissolution, over curing time, of portlandite, CaCo3 and C-S-H phases due to high pH (12.5 - 13) of the lime-clay-water systems (lime-...
Makeen's user avatar
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18 votes
2 answers
3k views

Why are some pH standard solutions 6.86 and 9.18?

I have calibrated pH sensors in the lab on several occasions and have used standards of 4.0, 7.0 and 10.0 usually. Recently I received a sensor and was tasked to calibrate it, but it requested ...
en_lorithai's user avatar
2 votes
0 answers
35 views

Water dissociation constant $K_w$ in vapour, or are there charges entities ($\ce{H3O+}$, $\ce{HO-}$,...) in water vapour?

When water is in vapour state, to which degree is there still some dissociation with the existence of charged species like $\ce{H3O+}$ and $\ce{HO-}$? (I would be interested by any reference to ...
The Quark's user avatar
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-3 votes
1 answer
104 views

Even in an acidic solution with a pH equal to 0, there are only 1 mol/L H3O+ ions, while there are approx. 54 mol/L water molecules

I find this sentence in my high school chemistry book to be confusing: "Even in an acidic solution with a pH equal to 0, there are only 1 mol/L H3O+ ions, while there are approx. 54 mol/L water ...
Authentic Melody's user avatar
-2 votes
1 answer
139 views

What's the pH of a solution knowing only pKa, mass and volume? (no molecular mass known)

Is it possible to calculate the pH of a given solution knowing only the pKa (but not the structure of the acid, i. e. its molecular mass), its mass and the volume of the solution? E. g. What is the pH ...
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