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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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Temperature compensation when measuring pH and how to calibrate

We want to measure the pH of liquid solutions (impure water) with a sensor that returns a voltage (by measuring the difference of potential inside and outside a glass bulb). The manufacturer provided ...
chris_cm's user avatar
-1 votes
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Algebraic method for modelling sodium acetate in solution

For a solution of sodium acetate ($NaA$), I want to find the concentrations of $H^+$, $OH^-$, $HA$ and $A^-$ via the algebraic method, being the total concentration of $NaA$ $C_A=0.25~\text{M}$, the ...
wolfram's user avatar
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H+ concentration of the mixture of a strong and weak acid

I reviewed the complete solution (hand-written) to the problem at Calculation of the pH of a mixture of a strong acid and weak acid. My question is why it is okay to apply the K1 value for the weak ...
Earl Whitney's user avatar
2 votes
2 answers
115 views

Why would the theoretical pH not match the measured pH when performing a titration of NH4OH with HCl?

I ran a weak base - strong acid titration experiment using an automatic titrator. I started with an aqueous ammonia stock solution (somewhere in the range of 0.1 - 2.5 wt.%) that was left open to ...
Nicholas Kam's user avatar
-5 votes
1 answer
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Why should the pH change when I add sodium hydroxide to water? [closed]

I am a student and I am trying to understand the concept of pH. If I add pure $\ce{NaOH}$ in water, it leads to the formation of $\ce{OH-}$ ions in the water. But this shouldn't lead to any change in ...
Bhaskar Ghildiyal's user avatar
-1 votes
1 answer
85 views

Relative concentrations of ions in pure water with a pH of 7

Not a chemist here as the last Chemistry class I took was millennia ago, so please be patient with me. The Chem taught today is so different (and much harder) than I remember. So, regarding pure water,...
David Musoke's user avatar
3 votes
0 answers
27 views

Non-binding buffer at pKa of roughly 6 that dissolves in ethanol?

I'm trying to find a proper buffer for my experiment, which I'd appreciate some suggestions on. I have a solution in which I want to measure the concentration of magnesium ions using a fluorescent ...
Helena's user avatar
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3 votes
1 answer
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Experiment on pH vs Rate of Electrolysis - what do the results actually say?

My experimental setup looks at using different pH solutions (of $\ce{H2SO4}$ and $\ce{NaOH}$) for electrolysis of water with a Hoffman setup and then measuring the rate of production of gas (note this ...
Eshwar Kolli's user avatar
3 votes
1 answer
315 views

By how much does sodium bicarbonate raise pH?

I am a pool-maintenance and service worker. I’m a little new to the field; however, none of the technicians I work with seem to have a definite answer for me. When raising the alkalinity in pools, we ...
Matias's user avatar
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1 vote
3 answers
176 views

pH at maximum concentration of a certain species (Phosphoric acid) [closed]

I am trying to find the pH at which $[H_{2}PO_{4} ^{-}]$ is maximum by only knowing the pKas. I have tried to derive an equation using kinetics but it failed [1]. After taking a look at the Sillén/...
David's user avatar
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3 votes
3 answers
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Can I use pH test papers with a dye-rich solution?

I'm working on some lactic acid fermentation of blueberries at home, and I'm trying to get a better handle on the process by logging the pH of the fermentation medium as the fermentation takes place. ...
josephkibe's user avatar
3 votes
0 answers
38 views

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 $\...
TheChemist's user avatar
1 vote
2 answers
198 views

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
0 votes
1 answer
39 views

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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-2 votes
1 answer
49 views

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
0 votes
0 answers
24 views

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
0 votes
1 answer
82 views

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
-5 votes
1 answer
112 views

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
1 vote
0 answers
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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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2 votes
0 answers
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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-...
emdura's user avatar
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0 answers
38 views

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
91 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
0 votes
1 answer
43 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
77 views

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
0 votes
2 answers
147 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
480 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
1 vote
0 answers
82 views

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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-4 votes
1 answer
61 views

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?
Mark R's user avatar
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1 vote
0 answers
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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 ...
wirrbel's user avatar
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-3 votes
2 answers
310 views

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
0 votes
2 answers
171 views

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
163 views

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
-4 votes
1 answer
171 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
172 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
  • 41
0 votes
1 answer
149 views

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 $\text{pH}$ =$1.5.$ $K_a$...
Aleph's user avatar
  • 185
-2 votes
3 answers
674 views

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
0 votes
0 answers
50 views

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
578 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 ...
Andrea's user avatar
  • 87
3 votes
1 answer
98 views

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)$...
Guimoute's user avatar
  • 139
-2 votes
1 answer
56 views

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
314 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
-2 votes
1 answer
94 views

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. ...
Kuhrta's user avatar
  • 65
4 votes
2 answers
118 views

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
  • 41
-2 votes
1 answer
92 views

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
  • 33
-2 votes
1 answer
102 views

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
410 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
  • 109
1 vote
0 answers
254 views

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
  • 35
1 vote
2 answers
290 views

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
0 votes
1 answer
186 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
  • 35
-1 votes
1 answer
55 views

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

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