Stands for Potential of Hydrogen and is a measure of how acidic or base an aqueous substance is.

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pH Indicators for Hoffman apparatus

I've read that bromothymol blue can be mixed in with the electrolyte in the demonstration of electrolysis using a Hoffman apparatus. The indicator clearly shows the local differences in pH for the ...
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Ultraviolet acid base indicator

Is there a chemical(s) that provides good discrimination between absorbance curves for different pHs in the UV light spectrum (100-400nm?)
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Titration and calculation of the number of moles after a mix

I have the following problem on an assignment that I don't understand. Given the following balanced equation for the titration of HCl with NaOH: $\ce{HCl + NaOH -> NaCl + H2O}$ The initial ...
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Is the volume of a protein substrate equal before and after an enzymatic reaction? (pepsin degrading egg white suspension)

I am trying to determine the reaction rate of pepsin at different pH values by performing an experiment. I am using egg-white suspension as the substrate and am adding differently concentrated ...
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Which is the strongest acid?

According to Wikipedia $\ce{HeH+}$ and Fluoroantimonic Acid are the strongest. According to Nature, Carborane acid is the strongest, but Wikipedia says fluoroantimonic acid is stronger... Links: ...
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62 views

How could the pH of this solution rise instead of fall when exposed to the atmosphere?

I have a couple of big barrels with a 50L demi-water solution of the following nutrients: $$ \begin{array}{rl} 200~\mathrm{\mu M} & \ce{NH4NO3} & +\\ 30~\mathrm{\mu M} & \ce{KCl} & ...
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pH of baking soda in water? [closed]

If I dissolve 1g of sodium bicarbonate powder into 400 ml of distilled water, what will the pH of the resulting solution be?
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How to verify the accuracy of a pH meter

One suggestion I received is that I prepare a solution of a known activity and probe the solution with the pH meter. The problem I see with this is that any error in solution preparation can lead us ...
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pH Changes in primary cells

Primary Cells - pH changes during discharge Alkaline Cell: Manganese Dioxide Zinc Alkaline Cell Anode (-) $\ce {Zn(s) + 2OH^{−}(aq) → ZnO(s) + H2O(l) + ...
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What happens when 0.02 mole NaOH is added to a buffer solution?

I am asking this question for my son. (This question is related but we still have our confusions.) We have one liter buffer solution of 4.74 pH which contains 0.1 mole $\ce{CH_3COOH}$ and 0.1 mole ...
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112 views

Adjusting PBS with HCl: pH drift after dilution of phosphate buffer

It is some kind of everyday lab science and with a feel of shame I cannot answer this observation. I noticed a pH drift (~0.5 units) of my 10X phosphate buffer (PBS), when I adjust the pH with ...
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59 views

What is the pH of a solution of HCOONa and HNO3?

Calculate the pH of an aqueous solution obtained by mixing 20 ml of $\ce{HCOONa}$ 0, 1 M and 5 ml of $\ce{HNO_3}$ 0,2 M. ($K_a$ of $\ce{HCOOH}$ $= 10^{–4}$) My try: The number of the moles involved ...
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Is it true that a pH higher than the pKa of an acid make the H automatically disassociate?

Will the hydrogen atom always disassociate if the pH of the solution is higher than the pKa of the acid?
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Using non-food grade NaOH for pH control

I would like to use non-food grade $\ce{NaOH}$ for $\ce{pH}$ water treatment. Any problem with this mixing with water that contains iron? The $\ce{NaOH}$ will be pumped into a well. As a $25\%$ ...
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44 views

Concentration of hypochlorous acid and hypochlorite

Given a total chlorine concentration and the pH and pKa of $\ce{HOCl}$, how would you find the concentration of $\ce{OCl-}$ and $\ce{HOCl}$ disinfectants? If the given total chlorine concentration is ...
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252 views

Calculating pH of diprotic and amphoteric solutions

I am trying to understand this problem and its corresponding solution (complete solution not shown) First off, from the above one can see that the equilibrium constants when $\ce{H2ASO4-}$ ...
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How much can the pH change through dilution?

Consider an acidic solution with Hydrogen ion concentration, $\ce{[H+]}$ of $10^{-5}\:\mathrm{M}$. Since $\:\mathrm{pH} = -\log \ce{[H+]}$ the $\:\mathrm{pH}$ of solution is $5$. Suppose we dilute ...
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Deviation from ideal solutions - activities and concentrations

What are some examples of solutions deviating significantly from ideal behavior, and, by extension, showing pHs significantly different from those predicted by usage of concentrations instead of ...
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85 views

Is there a means to measure pH without indicators?

I have created a solution that should contain hydroxide ions. Therefore, the pH > 7, but is there any way to roughly estimate the pH in absence of any indicator? Maybe using current, or checking ...
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47 views

Figuring out the pH

So, I'm refreshing my college chemistry a bit. Could someone give me a pointer on the following practice exercise? What is the pH @ 25 degrees Celcius in a bucket with 10liter pure water in which a ...
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31 views

Activities of Solutes - especially acids and bases

What is the concentration of hydrochloric acid needed to have a solution with the activity of the hydrogen proton = 1? I read 1.18 M somewhere but I am unable to find a corroborating source. Also, how ...
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77 views

How to calculate the pH of a buffered solution with Henderson Hasselbalch?

Lets say you have a buffered solution containing $0.50~\mathrm{M}$ acetic acid ($K_a = 1.8 \cdot 10^{-5}$) and $0.50~\mathrm{M}$ sodium acetate, and you want to calculate the $\mathrm{p}\ce{H}$ of ...
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Real life chemistry question

My freshwater fish tank has a pH of 5.8 and a KH value in excess of 40 or 720+ppm while still maintaining a water hardness of 20 ppm or GH< 1 now I am a math/phsyics student but I have taken both ...
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Protonation of Guanidine

Why is the $\ce{sp^2}$ hybridized nitrogen atom in guanidine the most basic? I know that as a general guideline, $\ce{sp^3}$ hybridized atoms are more basic than $\ce{sp^2}$. Bases are electron ...
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Calculating the pH of a dilluted aqueous KOH solution

I am not a chemist at all, but I wanted to help someone to get to the solution for the task of calculating the $\mathrm{p}\ce{H}$ of an aqueous solution of $0.01\:\mathrm{nM}~\ce{KOH}$ in water. ...
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No indicator is suitable when titrating weak acid with weak alkali

This was a statement in my book: A solution of a weak acid cannot be titrated with a weak base using an indicator to find the end-point because the pH change is too gradual close to the equivalence ...
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Galvanic Element: Silver Iodide and Standard Hydrogen cell

I have to calculate the $\mathrm{p}\ce{H}$ of the $\ce{H+}$ solution with the following info: $\ce{Ag(s) | AgI(s) || H2(g)(1atm) | H+(aq) (X mol/L) | Pt(s)}$ $E=0.1\:\mathrm{V}$ Temperature ...
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Why does pH affect fermentation?

I know that the lower the pH the faster fermentation occurs. Why does this happen?
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Accuracy of pH meters in MgSO4 solution

I bought a 2 pH meters several months back from Amazon for roughly $10 a piece. I couldn't tell you how they work, but here's the link on Amazon: ...
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Why does depurination happen at a higher pH (or under less harsh conditions) than depyrimidation?

I've always wondered why the N-glycosidic bond, which connects the adenine or guanine purine bases to their sugars, was the easiest to cleave via acid hydrolysis, or why purines have the lowest ...
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73 views

pH of a solution of acetic acid and ammonium acetate

After studying ionic equilibrium, I was just making some wild questions and I was unable to calculate the $\ce{pH}$ of this solution. Assume, 1 mole of each was added to $1L$ solution of water. My ...
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How to tell the pH of HC2H3O2?

The Question I am trying to Solve: The pH of a 0.500 M solution of $\ce{KC2H3O2}$. My First Question: How would I go about calculating this? My Second Question: Is the $\ce{H3O}$ in the middle of ...
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132 views

is water a non-metallic oxide? and hence acidic in nature?

I just read about non-metallic oxides in my textbook which says that non-metallic oxides are a compound formed of an oxide ion and a non-metal. It also said that they are acidic in nature. It gave ...
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51 views

What are the factors that affect the corrosiveness of an acid?

Acids are usually corrosive but what determines this? Is it the concentration of the acid or strength of the acid ($K_a$ value)?
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Thymolphthalein solubility

I already know that thymolphthalein is soluble in alcohols, very alkaline aqueous solutions, acetone, and propylene glycol methyl ether. My questions are what other solvents dissolve thymolphthalein, ...
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Amphoteric amino acid titration

Glycine $(\ce{NH2CH2COOH})$ is an amino acid with two $\mathrm{p}K_a$ values $(\mathrm{p}K_{a,1}=2.0, \ \ce{COOH};\ \mathrm{p}K_{a,2}=10.0, \ \ce{NH2})$. (a) If $0.01~\mathrm{mol}$ of this amino ...
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Determine the pH of mixture of two weak acids

We've two solutions : Solution 1 $HCOOH$ its concentration is $c_1=10^{-2} mol/l$ and its volume is $v_1 = 50 ml$ and its $pH_1 = 2.9$ Solution 2 $CH_3COOH$ its concentration is $c_2=10^{-2} mol/l$ ...
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68 views

Predicting the pH of a weak acid and weak base solution

I know that it is possible to predict whether combinations of acids and bases will be acidic, basic, or neutral: weak acid (WA) and strong base (SB) reacts basic strong acid (SA) and and weak base ...
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How much hydrolysis will likely occur of the following bonds at pH 1-4 in the time period of 1-3 hours?

The bonds are: (I have given pictures of what I mean in case there's any ambiguity that I leave open in these questions. Also so that if you want to number the R groups you've got a head-start) ...
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What is the unit of pH?

I'm making some graphs and I have to label the axes. I want to be extra careful and put the units in even though the meaning of $\text{pH}$ is well known. But I have a problem (though a simple one): ...
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pH and materials selction

I working on the Navy study guide for their nuclear engineering programs and I am not a Chemist. Thus, I have come here to try and develop a better understanding of the subject matter. I am trying ...
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Given the volumes: determine the pH and the final temperature of a mixture knowing only the initial pH and the temperature of the un-mixed components

I have a pretty basic question but the last time I took Chemistry was in 2007. I am studying the Navy's Nuclear study guide for their interviews and one of the question I am faced with is below. ...
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What is the pKa of the oxonium / hydronium / H3O+ ion?

Although the wikipedia page on Hydronium indicates a pKa of -1.74, I noticed in the discussion of this page that the subject seems debated (cf. http://en.wikipedia.org/wiki/Talk:Hydronium#pKa.3F) ...
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Cant extract a pyridine tetrazole

I have synthesised a compound which is basically a pyridine ring connected to a tetrazole. The procedure suggested to precipitate it at pH 1 but it did not. It then suggested to extract it with ethyl ...
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161 views

Volume required to dilute solution for a pH change

A 100 ml solution of NaOH has a pH of 13. What volume of water, in mL must be added to change the pH to 11? My Steps: So, begin by calculating conc. of [OH-] for pH 13. Then find the moles by ...
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Red Cabbage Indicator colour change with Sodium Metabisulphite

I made some pH indicator by boiling and straining cabbage juice and in an effort to keep it from spoiling for a while without having to store it at fridge temperatures I added some wine making ...
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Approximate time for pure water pH to equilibrate in open air?

I'm a complete non-chemist, so I don't know how to calculate this, or even what to google for (my searches yielded esoteric research papers). I'm doing some hobby experiments, and I'd like to know ...
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Henderson-Hasselbalch pH question help [closed]

I need help on this: Determine the volumes of .1M $\ce{CH3COOH}$ and .1M $\ce{CH3COONa}$ required to prepare 10.0 mL buffer of each of the following pH values: 3.7 4.7 5.7
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What is the reason a grain of salt alters the perceived bitterness of coffee by such a high degree?

Coffee served hot can be quite bitter (presumably high pH). Several people I have known will add a single grain of salt to the coffee - which reduces the perceived bitterness. My question is: What ...
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Calculating approximate pH of polyprotic acids

When I took up ionic equilibria and titrations after a long break, I found it hard to solve the questions regarding pH calculations of polyprotic acds. Consider these two questions as examples:- ...