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

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Decreasing pH Levels [on hold]

You have a very basic solution (pH 9) and need to make it less basic (pH 7) what could you add to change the pH and how would it change the pH at a chemical level?
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2answers
27 views

Henderson-Hasselbalch Question

I am struggling with what appears to be an extremely easy pH problem that uses the Henderson-Hasselbalch equation. The problem and answer provided by the book is given below. I understand where the ...
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pH of diluted mixture of HCl in differing initial concentrations [on hold]

Problem: 200 ml of 1 M $\ce{HCl}$ is mixed with 300 ml of 6 M $\ce{HCl}$ and the final solution is diluted to 100 ml. Calculate the molar concentration of $\ce{H+}$.
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1answer
33 views

Calculating pH: Weak Acid, Strong Base

This is a question that had me puzzled for quite a while. I feel that information is missing. A weak acid, $\ce{HA}$, $K_a = 1.0$ x $10^{-4}$, is titrated with $\ce{NaOH}$. At the equivalence ...
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1answer
49 views

How do I calculate how much NaOH I need to add to get a new pH?

A 100 ml $\ce{HCl}$ solution has a pH of 3.7 You want the solution to get a pH of 4.5. You have a solution of $10\ \mathrm M$ $\ce{NaOH}$. How much $\ce{NaOH}$ do you need to add to to the $100\ ...
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51 views

pKa of domperidone

The p$K_{\rm a}$ of domperidone is 7.9. A typical tertiary amine has a p$K_{\rm a}$ ~9.8. Why is the p$K_{\rm a}$ of domperidone lower? I think it is the $\ce{N}$ from piperidine. Is it because of the ...
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2answers
81 views

Why is the pKa of the thiol group in N-acetylcysteine higher then the pKa of the thiol group in cysteine?

I understand why cysteine has a $\mathrm pK_{\mathrm a}$ of 8.3. But the $\mathrm pK_{\mathrm a}$ of thiol in N-acetylcysteine is 9.27. Since there is an acetyl group attached to the nitrogen, doesn't ...
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2answers
33 views

Solution for storing a glass electrode

What kind of storage solution is required for a glass electrode? Is 3 M $\ce{KCl}$ sufficient for this purpose? If so, what is the approximate pH of that solution (the solution I use presently has a ...
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1answer
95 views

pH of sodium metasilicate anhydrous vs pentahydrate when dissolved in water

I'm not a chemist and don't remember much chemistry from school, so please forgive a naive question (I've read the Wikipedia article on sodium silicate though). I'm researching this topic to make ...
5
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1answer
38 views

NaOH Normality Slowly Changing

Our lab uses a sodium hydroxide solution of a (theoretically) known normality (0.8000 - 1.0000) to titrate product samples for quality control. However, we suspect that the normality of the ...
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0answers
46 views

Is the pH of a solution (orange juice) affected by the presence of a metal?

Is the pH of a solution (orange juice) affected by the presence of a metal (aluminium, tin or iron for example)? I know that the metal will corrode in the presence of an acid (citric acid in this ...
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130 views

pH of NaCl and NaOH solution?

What is the pH of a solution of 100 g of $\ce{NaCl}$ and 5 g of $\ce{NaOH}$ in 1 L of water? I suppose added $\ce{NaCl}$ shouldn’t change the pH since $\ce{NaOH}$ dissociates fully, so there is no ...
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1answer
62 views

Atmospheric Nitrogen gas and human body pH buffers

It looks like the human body doesn't have the ability to breakdown atmospheric $\ce{N2}$, as of now $\ldots$ So an enzyme like nitrogenase (found in cyanobacteria) fixes $\ce{N2}$ and produces ...
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1answer
69 views

Ph of acid would be one? [closed]

I am interested in the chemical lsd or "acid". I wanted to know if lsd is acid in its pure form would that mean it is water?
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2answers
107 views

About pH of an aqueous solution of SO2

How can I compare pH of an aqueous solution of $\ce{SO2}$ with that of pure water qualitatively? And I want to know what happen to the pH of an aqueous solution of $\ce{SO2}$ if I aerate it by ...
2
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1answer
203 views

Phosphate buffer from phosphoric acid and K2HPO4?

Is it possible to make a solution of ph 7 phosphate buffer solution using phosphoric acid and $\ce{K2HPO4}$ ? How can I calculate the amount of $\ce{K2HPO4}$ needed for 1L of phosphoric acid ? Edit: ...
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3answers
347 views

Why amino acids (Zwitterion) become either negative or positive at low and high pH solutions?

The amino acids are Zwitterions. In neutral pH, an Amino acids' amino group has a + postive charge and Carboxyl group has - negative charge. They cancel each others charge thanks to the H that's ...
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82 views

What's the pH of HCl?

I have to solve the following problem: What is the pH of $10^{-5}\ \ce{mol/L}$ chloridic acid (HCl) if it's 100% dissociated? I don't know how to use the existing formulas to come to the ...
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3answers
113 views

Is the Henderson–Hasselbalch equation volume independent?

Looking at this equation $\mathrm{pH} = \mathrm{p}K_\text{a} +\log\frac{[\ce{CB}]}{[\ce{A}]}$ makes me think that it is concentration independent. What I mean is, when we look at ...
5
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1answer
877 views

How to find pH by mixing two solutions of different concentrations?

A mixture is made by combining 110 mL of 0.15 M $\ce{HCl}$ and 215 mL of 0.055 M $\ce{HI}$. What is the pH of the solution? $$\ce{HCl -> H+ + Cl-}$$ $$\ce{HI -> H+ + I-}$$ According to ...
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3answers
604 views

Calculating Buffer Capacity

I completed a titration of Ammonium Acetate buffer solution and to it I added 2M Hydrochloric Acid. I measured the initial pH of the buffer solution before any acid was added and I used methyl ...
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1answer
36 views

Purification of water with ferric chloride

Ferric chloride ($\ce{FeCl3}$) is a chemical used in water treatment. If ferric chloride is added to a water sample containing calcium bicarbonate, would the $\mathrm{pH}$ of the solution decrease or ...
5
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1answer
78 views

Determining (approximately) the amount of a strong base needed to change a buffer's pH by a certain number of units

I'm measuring buffer capacity by titrating $\ce{NaOH}$ into a buffer of $\ce {H3PO4 + NaH2PO4}$. I'm measuring buffer capacity by recording the amount of $\ce{NaOH}$ required to increase the ...
5
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1answer
136 views

Investigating a factor affecting buffer capacity

I'm preparing for an experiment to investigate some factor affecting buffer capacity. At the moment, I'm looking at using a $\ce{NH_3}$ ($2\,\mathrm{M}$) $+$ $\ce{NH_4Cl}$ buffer, but I'm not sure ...
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216 views

How to calculate the pH of a saturated solution from its solubility constant Ksp and acidity constant Ka?

Given that $K_{\mathrm{sp}}(\ce{CaF2})=3.2\cdot 10^{-11}$, $K_{\mathrm{a}}(\ce{HF})=10^{-5}$, and $K_{\mathrm{w}}=10^{-14}$. Calculate $\mathrm{pH}$ of saturated $\ce{CaF2}$. Edit: Since my ...
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1answer
104 views

What is the necessary volume of concentrated HCl to prepare a solution with a pH of 1.8?

Here is my question: What volume of a concentrated $\ce{HCl}$ solution, which is $36.0\%$ $\ce{HCl}$ by mass and has a density of $1.179~\mathrm{g~mL^{-1}}$, should be used to make ...
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53 views

Dissolving Aspartic acid in vinegar?

I am trying to dissolve aspartic acid into vinegar as use as a carbon source in saltwater aquariums. It does not dissolve. I was told to increase the pH and it will work? What is the best way to ...
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1answer
78 views

Ksp calculation of Cr(OH)2

At $25~\mathrm{^\circ C}$, $10.24~\mathrm{mg}$ of $\ce{Cr(OH)2}$ are dissolved in enough water to make $125~\mathrm{mL}$ of solution. When equilibrium is established, the solution has a $\mathrm{pH}$ ...
5
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1k views

pH of dilute HCl solution

What is the pH of a solution of $3.4 \times 10^{-10}$ moles of $\ce{HCl}$ in a volume of $150.7L$? This is dilute so I expect pH to be high. $\frac{3.4 \times 10^{-10} mol}{150.7L} = 2.26 \times ...
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1answer
43 views

pH of a weak base calculation

Calculate the $\ce{pH}$ of a $100$ $\ce{mL}$ solution containing $0$$.0375$ moles of the weak base, Sodium Benzoate, $\ce{C6H5COONa}$. $$\ce{C6H5COO + H2O -> C6H6COO- + OH-}$$ $$\frac{0.0375 ...
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1answer
267 views

Why does an acid have a low pH value?

When study biology in class, I don't know how my teacher get to the topics on pH value. So, she says that pH stands for percentage hydrogen. Then, I thought there is something strange about it cause ...
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1answer
187 views

What is the role of pH in azo coupling reaction of diazonium with phenol and aniline?

Why is it so that azo coupling with phenol needs basic pH (9–10) and with aniline it needs acidic pH (4–5). How does pH participate in the mechanism? I have searched the internet for quite a while ...
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1answer
89 views

Potentiometric titration using a pH meter

Why is the pH of a buffer solution measured before measuring the pH of an unknown solution? I do not have any idea about it. I had read a chapter about ionic equilibrium and electrochemistry, but have ...
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2answers
613 views

Diluting acetic acid to obtain a solution of pH 5 [closed]

What percent of a solution needs to be acetic acid for a particular $\mathrm{pH}$? I have 100% acetic acid, and want $1~\mathrm{L}$ of solution with a $\mathrm{pH}$ of 5. I've done some research, but ...
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2answers
94 views

Equilibrium constants for lewis acids such as Ca2+

I need to calculate the theoretical $\mathrm{pH}$ in a $50~\mathrm{mL}$ water solution where $6.4\times10^{-4}~\mathrm{g}$ of $\ce{Ca^{2+}}$ is present. The reaction I base this on is the following ...
3
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1answer
87 views

Finding pH of a buffer

What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M methylamine, $\ce{CH3NH2}$, with 25.00 mL of 0.10 M methylammonium chloride, $\ce{CH3NH3Cl}$? Assume that the volume of the solutions ...
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3answers
72 views

Determining the H⁺ Concentration of Na₃PO₄

The problem asks to determine the $[\ce{H+}]$ in a $0.20~\mathrm{M}$ solution of $\ce{Na3PO4}$. The $K_\mathrm{a}$ of $\ce{HPO4-}$ was given as $4.5\times 10^{-13}$, which then allows one to calculate ...
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2answers
64 views

After mixing, which species has the dominant affect on the pH of the solution that remains?

A solution is created by mixing $250\,\mathrm{mL}$ of $1\,\mathrm{M}$ $\ce{HCl}$, $250\,\mathrm{mL}$ of $1\,\mathrm{M}$ $\ce{CH3COOH}$ and $500\,\mathrm{mL}$ of $1.5\,\mathrm{M}$ $\ce{CsOH}$. The ...
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1answer
75 views

What is the pH of CsBr?

a) 3.8 b) 7 c) 9 d) 12 My Attempt: $\ce{Cs+ + H2O <<=> CsOH + H+}$ (because $\ce{CsOH}$ is a strong base, the forward reaction should not occur right)? $\ce{Br- + H2O <<=> HBr + ...
4
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1answer
139 views

Alkaline glycine buffer molarity

Having never prepared a buffer solution before, I am hoping for a little help in understanding the process. This method I plan to use calls for a 0.1M glycine buffer at pH 10.6. Some internet ...
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1answer
120 views

Effect of dilution on pH for HCl

Is it necessary to consider common ion effect when suppose a strong acid like HCl is added to water? For example in this question: 10 mL of $10^{-6 } \ce{mol/L \ HCl}$ solution is mixed with 90 mL of ...
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1answer
204 views

Can I make a pH 7 buffer from phosphoric acid and sodium hydroxide?

I am an electronics guy with not so much knowledge of chemistry. I would like to prepare a pH 7 buffer to test pH meters. All web references I have found so far describing how to make a phosphate ...
4
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1answer
510 views

Calculating pH for titration of weak base with strong acid

Calculate the pH at the equivalence point for the titration of 0.130 M methylamine ($\ce{CH3NH2}$) with 0.130 M $\ce{HCl}$. The Kb of methylamine is ${5.0×10^{–4}}$. So I started with the equation: ...
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How is the pKa of extremely weak acids determined?

According to Wikipedia the conjugate acid of LDA has a pKa of about 35 - which is in line with figures I've seen elsewhere. How then can such a weak acid's pKa of be determined? If the determination ...
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1answer
54 views

What's a good resource/book on pH measurements?

Most resources on pH and the electrochemistry behind it that I've found are IMHO too superficial. For example, they explain that an electrode with less than 80% slope should be discarded, but not why ...
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47 views

Can I use my extech pH 60 meter to measure soil pH if so how?

Can I use my extech pH60 meter to measure soil pH if so how? I included a link to the meter. Extech pH 60
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3answers
911 views

How concentrated can an acid be?

How concentrated can an acid be without it being supersaturated? Is there a certain limit to how concentrated an acid or base can be? When I mean concentration, I mean molarity; so how concentrated ...
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1answer
114 views

Chalcogens' hydrides as acids?

I've noticed that chalcogens never form binary acids, and instead end up like water, with very little acidity. Why is this? Or am I wrong and there's a counterexample, if so please give it.
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Slow acidification process

I'm trying to find a substitute of Glucono delta-lactone (GDL). This food additive is usually used to produce silk tofu. Because of its slow hydrolysis the pH decreases very smoothly, which results in ...
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1answer
373 views

Finding new pH after NaOH added to buffer solution

I have a buffer containing 0.2 M of the acid $\ce{HA}$, and 0.15 M of its conjugate base $\ce{A-}$, with a pH of 3.35. I need to find the pH after 0.0015 mol of $\ce{NaOH}$ is added to 0.5 L of the ...