Stands for Potential of Hydrogen and is a measure of how acidic or basic an aqueous solution is.

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Can Henderson-Hasselbalch equation be used to determine the pH of a solution when a strong base and a strong salt of that base stay together?

The following problem I have stated was not given to me as a homework. I have found this one in my textbook. I have solved it in my own way, but I'm not sure about the correctness of my procedure. I ...
-1
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19 views

Correlation of pH estimation 0.1M KH2PO4 with the behavior of the base and acid constituents of the salt

My measured value for the pH of a $0.1~M \ce{KH2PO4}$ solution was $4.6$. This is close to the value obtained by assuming no role for the $\ce{K+}$ ion and considering the reactions of $\ce{H2PO4-}$ ...
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1answer
19 views

Why is it correct to assume a neutral amino acid is entered in this problem?

The questions is: $1.812\ \mathrm{g}$ of a crystallized α-amino acid ($\mathrm{p}K_\mathrm{a1} = 2.4, \mathrm{p}K_\mathrm{a2} = 9.7$) has a $\mathrm{pH}$ of $10.4$ when dissolved in $100\ \...
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38 views

Which component decides what my pH will be in an aqeous solution?

I have an aqueous ammonium cinnamate solution of 0.5 M and want to know how I can calculate the pH of this solution. It is unclear to me which of the two components will have the upper hand as they ...
0
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1answer
62 views

Calculate the pH of Na2CO3

Given information: $K_\mathrm{a}(\ce{H2CO3}) = 4.3 \times 10^{-7}$, $K_\mathrm{a}(\ce{HCO3-}) = 4.8 \times 10^{-11}$, ${{\ce{[Na2CO3]}=0.20\ \mathrm{M}}}$ This was a question in an exam and I'm ...
0
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1answer
34 views

Proof of buffers inability to maintain exact same pH

I was wondering if the following is a legitimate proof of the statement above. Assume we have HA -> A- + H+ where [HA] + [A-] is our buffer. If we add a small amount of H+ one of two things will ...
4
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1answer
71 views

Is there any notion of pH out of solution?

For example, could one define a $\mathrm{pH}$ for pure acetic acid? It's a weak acid in water, but if someone handed you $1~\mathrm L$ of pure acetic acid, what would its $\mathrm{pH}$ be?
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1answer
60 views

Why do some acids have pH 8? [closed]

Is it necessary for an acid to have pH less than 7? If no, please elaborate with examples.
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49 views

Phenolphthalein as a indicator for the titration of benzoic acid

Question: Justify the use of phenolphthalein $(\mathrm{p}K_\ce{in}=9.4)$ as a indicator for the titration of benzoic acid $(K_\mathrm{a}=6.3\times 10^{-5})$ with $\ce{NaOH}$. My attempt: I can ...
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0answers
26 views

Identification of bases by pH paper

pH paper tells whether the solution is an acid or a base by looking at the concentration of H+ ions in the solution. When an acid is put into water H+ ions and the anions in the acid are released. ...
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1answer
39 views

Finding pH using the -log, why does my calculation differ from the book's answer?

An aqueous solution containing 0.0020 mol/L barium hydroxide, what is the pH? I do the following: 14-(-log(0.0020))=11.3pH. The answer is 11.6. 2.0*10^-3 mol/L sodium hydroxide solution, what is the ...
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1answer
31 views

Sodium fluoride and varying pH - HF risk

I'm looking into conducting an experiment on the adsorption of fluoride (for my International Baccalaureate Extended Essay). As I will be investigating the role of $\mathrm{pH}$ in adsorption capacity,...
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34 views

Neutralization of sodium percarbonate

At the moment, I have been asked to improve the methods given in my experiment to increase the efficiency of the results. One of the steps I am currently looking at is the neutralization of sodium ...
0
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1answer
50 views

How does a lower pH change the alcohol concentration of wine?

I have been told it that when the pH of wine is lowered the alcohol concentration will decrease because of Le Chatelier's Principle. Which states; if a equilibrium is disturbed by changing the ...
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0answers
36 views

Determining concentration of salts of polyprotic buffer solution

I'm looking into making a formula for making citric acid buffer solution from citric acid monohydrate ($\ce{C6H8O7.H2O}$) and sodium citrate $\ce{C6H5O7Na3.2H2O}$, with adjustable pH and molarity of ...
3
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2answers
380 views

Can hydrofluoric acid etch glass at a pH of 7.0?

Will it still etch glass when very dilute? Will the reaction still proceed slowly? At what pH will the reaction stop completely? "Although hydrofluoric acid is regarded as a weak acid, it is very ...
0
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2answers
57 views

Why does milk clot while making yogurt?

Why does milk clot when it becomes yogurt? Is it only because of the decrease in the $\mathrm{pH}$ of milk? If it does so, what is happening when I increase the $\mathrm{pH}$ level? And by decreasing ...
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2answers
106 views

Why isn't CH3OH the most basic if it contains OH?

I was asked to find the most basic solution from the following: $\ce{K2SO4}$ $\ce{CH3OH}$ $\ce{Na2CO3}$ $\ce{(NH4)2CrO4}$ $\ce{BaCl2}$ I know that I have to identify the solution that ...
3
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2answers
97 views

Combining acid dissociation constants to determine pH of diprotic acid

If I have a diprotic acid with $K_{\mathrm{a1}}$ and $K_{\mathrm{a2}}$ as the acid dissociation constants, why can't I calculate the final $\mathrm{pH}$ using $K = K_{\mathrm{a1}}\cdot K_{\mathrm{a2}}$...
0
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1answer
25 views

Why does the reference electrode in potentiometry have a diaphragm?

I am studying about potentiometry and pH-measurement with a glass electrode. I don't understand why the reference electrode has a diaphragm and is immersed in the measured solution. If I got it right, ...
30
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2answers
5k views

What is the pH of ice?

The pH of pure liquid water depends on temperature. It is about pH = 7.0 at room temperature, pH = 6.1 at 100 °C, and pH = 7.5 at 0 °C. What happens to the pH (or to the ion product) of pure water ...
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1answer
88 views

Why do acids mix in water faster than bases?

I have $100\ \mathrm{L}$ of water in a tank with an mixer inside and want to know how fast the tank mixes at a given rpm-setting. I am adding $50\ \mathrm{mL}$ of $2\ \mathrm{N}\ \ce{HCl}$ and see ...
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40 views

pH of a double buffer

If $1,2,3,4$ moles of $\ce{H3PO4}$,$\ce{NaH2PO4}$,$\ce{Na2HPO4}$ and $\ce{Na3PO4}$ respectively are mixed together to form an aqueous solution of $1$Litre , resulting $\ce{pH}$ is? This question has ...
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0answers
23 views

The potential range of the cyclic voltammetry of CoCat in KPi made of D2O

I have a phosphate buffer adjusted to pH 7, and another phosphate buffer made of deuterium oxide (D2O) adjusted to pH 6.6 (pD 7). I want to conduct cyclic voltammetry of cobalt oxide catalyst in these ...
4
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1answer
123 views

How to calculate pH of a solution when H3PO4,NaH2PO4,Na2HPO4 and Na3PO4 are mixed together in certain amounts to form a solution?

How to calculate pH of a solution when $\ce {H3PO4}$ ,$\ce {NaH2PO4}$,$\ce{Na2HPO4}$ and $\ce {Na_3PO_4}$ are mixed together in certain amounts to form a solution? I know how to calculate pH when ...
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52 views

What is the PKa of hexafluorosilicic acid?

I've tried Googling this for about an hour and couldn't find the information on any Chemistry resource sites. Given the formula F6H2Si, is it possible to calculate the PKa, or can this only be worked ...
0
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1answer
52 views

What actually happens when citric acid is added to a highly alkaline soap solution?

A few days ago I made an experiment. I diluted a few small chunks of bar soap with 20 ml of water. I then measured the ph of the solution which was around 10. I then added a tiny amount of citric acid....
0
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1answer
50 views

Calculation of Ka and pH

$$\ce{H3PO4 <=> H+ + H2PO4-}$$ $$K_{\mathrm a1} = 7.4\times10^{-3}$$ $$\ce{H2PO4- <=> H+ + HPO4^2-}$$ $$K_{\mathrm a2} = 6.2\times10^{-5}$$ $$\ce{HPO4^2- <=> H^+ + PO4^3-}$$ ...
3
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41 views

How to determine pH of food in order to avoid unsuitable storage containers

In an acidic (lemon-containing) sauce I had placed a metallic spoon. A few days later it had a metallic taste. Stainless steal might be a significant source of nickel, chromium and iron [1]. Also, ...
4
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1answer
72 views

Is there any reason to fear personal exposure to rain with a pH of 3.1?

Where I live now there can be significantly acidic rain. The government posts measurements for many cities and there can be stretches for days or longer with reported pH of 3.2 or 3.1. I even saw 2.9 ...
3
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1answer
54 views

Dissolving Tylenol Science Experiment - why is it fastest in distilled water?

My son has a science experiment for class to dissolve Tylenol (325mg acetaminophen) in 3 different solutions (125 mL volume each): Distilled water Vinegar (1 part white vinegar to 4 parts water) ...
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11 views

Determining the min/max change a fluid can exert over a different fluid's pH

...assuming you know the pH of both fluids, but not the chemical structure. Suppose we mix: 50ml of mystery fluid A @ 7.4 50ml of mystery fluid @ 6.4 Is there a shortcut to determine what the ...
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1answer
131 views

Is NaH2PO4 and Na2HPO4 buffer a neutral buffer? [closed]

My teacher mentioned in class that a mixture of two salts derived from polybasic acid functions as a buffer solution. But is it a neutral buffer or acidic buffer?
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1answer
51 views

Which pH approximation to choose when?

When I learned about pH approximations in school, I was told that each approximation fits to a certain acidity strength/pKa range. Those ranges are grouped in common categories (pKa borders are only ...
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2answers
265 views

pH of a buffer made with H3BO3 and KH2BO3

The Problem Calculate the pH of a buffer that is 0.200M $\ce{H3BO3}$ and 0.122M $\ce{KH2BO3}$. The $K_a$ for $\ce{H3BO3}$ is $7.3*10^{-10}$ What I Tried For each of these methods, I used 0.200M as ...
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1answer
63 views

why the buffer capacity depends on the ratio of salt and acid in acidic buffer?

According to the Henderson–Hasselbatch equation when pH = Pka for any buffer solution then why we say that this is the best buffer?
0
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1answer
52 views

Getting the wrong pH value, according to data and online calculator

I'm doing a titration problem with a week acid and strong base, I used experiment data and an online calculator to check my answer, but my pH I calculated is a bit off. Can anyone see where I messed ...
1
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1answer
49 views

Glass electrode pH measurement

How is the potential difference between the outer and inner surface of the glass bubble in a glass electrode measured if an Ag/AgCl wire is used as the indicator electrode and Ag/AgCl/KCl is used as ...
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3answers
320 views

Is LiOH a weaker base than NaOH?

I'm confused about which is the stronger base. Note: I'm not interested in "why," but rather what the "real" pKb values are. $$ \small \begin{array}{lcc} \text{Data for Alkali Metal Hydroxides} \\ ...
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1answer
33 views

change of pH in urine

I'm looking to lower the pH of a urine solution from 12 to 7. I'm planning to do it in 2 ways. First is to use a strong acid such as HCl. Secondly, using vinegar, a weak acid. However, I am having ...
2
votes
1answer
47 views

Is it possible for a liquid chemical to have a pH value lower than its aqueous solution?

During the QC check of one of the products that we make as a company, the product had a $\mathrm{pH}$ of $10.44$ on one $\mathrm{pH}$ meter and $10.20$ on the other. (The product is a liquid, so it's ...
3
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2answers
77 views

How to calculate Ka for hydronium and Kb for hydroxide? [duplicate]

I am wondering how to calculate the $K_a$ for hydronium, $H_3O^+$, and the $K_b$ for hydroxide. Because hydronium undergoes the equilibrium $\ce{H_3O^+(aq) + H_2O (l) <=> H_2O (l) + H_3O^+ (aq)...
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1answer
64 views

How to get specific concentration of carbonic acid in solution?

I wanted to know if there is a way of getting specific quantities of carbonic acid? Carbonic acid is water + $\ce{CO2}$ but not all the $\ce{CO2}$ dissolves in water. So if I wanted $5\:\mathrm{g}$ of ...
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1answer
40 views

Why do the first and second ionizations of a diprotic acid produce the same hydronium ion concentrations in solution?

I was going through Oxtoby Chemistry when I got confused by the following passage in the textbook. It said that "two simultaneous equilibria are involved in the ionization of a diprotic acid such as ...
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0answers
46 views

Why does final pH value of buffer solution after addition of acid not depend on amount added?

I'm brushing up and the example in my book is against my intuition. A buffer solution contains 1.0 mol/L acetic acid and 1.0 mol/L sodium acetate. The solution is at pH = pKa = 4.75. What's the ...
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24 views

How to calculate molar concentration of phenol red when mixed with water and a buffer?

The concentration of phenol red is 1E-4 M. The initial volume used was .1 mL and is then mixed with .9 mL of water and 4.0 mL of a .1M borate buffer of pH 9.8. I used a simple M1V1 = M2V2. Where M1 = ...
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14 views

pH of a solution 1) disregarding activity and 2) using ionic activity coefficients [closed]

A weak acid with MW= 356 and pKa= 2.76 is dissolved in an isotonic NaCl solution to make a 3% w/v solution. What is the pH of this solution 1) disregarding activity and 2) using activity coefficients (...
2
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1answer
47 views

pH Determination

I have a cubic box of length $L=12.42\ \mathrm{\overset{\circ}A}$, containing $60\ \ce{H2O}$ and $1\ \ce{H+}$ ion. What is the $\mathrm{pH}$ of the system? Following the basic definition, $\mathrm{pH}...
0
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0answers
27 views

Why does plaster get rusted when exposed to acid solutions?

Why does plaster in the beaker numbered 6, get a brownish color? It is submerged in distilled vinegar with $\mathrm{5\%}$ of acetic acid. Has it oxidized? Has it absorbed the vinegar? what is the ...
1
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1answer
32 views

Predicting changes in pH of water when chlorinating using two different methods

Two methods for chlorinating water are using Chlorine gas ($\ce{Cl2}$) or calcium hypochlorite ($\ce{Ca(OCl)2}$). By using chemical equations how can you predict the pH of the water brought about by ...