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

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276 views

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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10 views

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 ...
3
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1answer
59 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 ...
2
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1answer
46 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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1answer
20 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 ...
3
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1answer
34 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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2answers
71 views

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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2answers
91 views

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 ...
5
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2answers
166 views

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. ...
2
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1answer
28 views

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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0answers
33 views

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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2answers
36 views

Why does pH affect fermentation?

I know that the lower the pH the faster fermentation occurs. Why does this happen?
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1answer
41 views

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: ...
7
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93 views

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 ...
0
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1answer
41 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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2answers
52 views

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 ...
0
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1answer
59 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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1answer
33 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)?
2
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1answer
38 views

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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1answer
70 views

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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3answers
112 views

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 $c_2=10^{-2} mol/l$ ...
0
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1answer
45 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 ...
2
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0answers
38 views

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) ...
9
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2answers
2k views

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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3answers
56 views

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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2answers
115 views

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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0answers
126 views

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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1answer
50 views

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 ...
2
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1answer
57 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 ...
3
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1answer
43 views

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 ...
8
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2answers
235 views

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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1answer
57 views

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
2
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1answer
96 views

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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1answer
106 views

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:- ...
7
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3answers
1k views

the reason behind the steep rise in pH in the acid base titration curve

Most books refer to a steep rise in pH when a titration reaches the equivalence point. However, I do not understand why... I mean I am adding the same drops of acid to the alkali but just as I near ...
1
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1answer
736 views

Shouldn't the pH at the equivalence point always be 7?

I learned in class that the equivalence point in an acid-base titration is reached when the solution contains equal number of moles of $\ce{OH-}$ and $\ce{H+}$ ions. However, in a weak acid and strong ...
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2answers
2k views

What is the pKa Range for weak acids and bases?

Am I correct in assuming that the following is true? $pK_a < 3$ is for a strong acid $3 < pK_a < 7$ is for a weak acid $7 < pK_a < 11$ is for a weak base $pK_a > 11$ is for a ...
0
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3answers
397 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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0answers
181 views

Difference in pka between PEG and Ethylene glycol?

What is the difference between the pKa for Polyethylene glycol (PEG) and Ethylene glycol (EG)? Is there a difference? There are also different types of PEG, monomethyl ethers and dimethyl ethers, do ...
0
votes
0answers
150 views

Calculating the pH of a buffer made from KHP (potassium hydrogen phthalate)

I have a question regarding the pH of a buffer, and how to calculate it. The buffer was prepared by: 1) Mixing 25 cc of 0.1M NaOH solution to 25cc of 0.1M KHP solution (i.e. potassium hydrogen ...
0
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1answer
74 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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0answers
154 views

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 $H^{+}$ ions in solution increases because dissociation of the weak acid increases This didn't make sense ...
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0answers
69 views

Why is Buffer capacity maximum when the ratio of its components is 1?

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 ...
0
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2answers
101 views

What is the importance of using a pka value instead of a pkb value when describing drug chemistry?

Why do we only consider the $pK_a$ value of a drug regardless of whether it is an acid or base? Why do we not use the $pK_b$ value?
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1answer
67 views

What is the correct form for the acid-base equilibrium constant potential: pK_a or pK_A?

In science, the acid-base equilibrium constant potential is denoted or depending of the source (lowercase or uppercase A). Since it is the potential of the acide-base equilibrium constant defined as ...
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0answers
24 views

What are the products formed by a typical wood fire? [duplicate]

What are the products formed by a typical wood fire? I tested the ash from my fireplace and found it to be on the acid side. While this question has been partially answered in answers to another ...
0
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1answer
137 views

why should colorimetric titration of weak acid and weak base should not be done in laboratory?

why should colorimetric titration of weak acid and weak base should not be done in laboratory? Also how to draw the curve of weak base or Weak acid added and ph..??
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0answers
28 views

Isoelectric point pH, mV, for a metal oxide nanopowder

I'm trying to make a solution of TiO2 that will coat stuff in as dense a monolayer as possible. To do so, I'm using nano sized TiO2 particles and trying to get them to get as close to each other as ...
0
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1answer
262 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 ...
0
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1answer
57 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?