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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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138 views

How to solve for concentration of two equilibrium reactions with finite equilibrium constants?

I have a small problem of equilibrium that I counldn't solve. I want the exact answer. No approximations please. $$ \begin{array}{ll} \ce{H2O + H2O <=> H3O+ + OH-} &\quad\left(K_w = 1\cdot ...
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120 views

Why is it difficult to measure the pH of environmental water samples accurately (near 7)?

I've read in several places (edit: 1, 2, 3, 4, 5, 6, 7, 8. 9, 10, 11, 12) that there are many practical factors that make accurate pH measurements of roughly neutral environmental water samples more ...
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1answer
88 views

Hydrolysis of a salt B2X

An aqueous solution of soluble salt $\ce{B2X}$ has concentration of 0.1 M. Given data : $\ce{K_b(BOH) = 2 × 10^{–5}}$ $\ce{K_{a1}(H2X) = 2 × 10^{–7}}$ $\ce{K_{a2}(H2X) = 5 × 10^{–10}}$ ...
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233 views

How do you neutralize pH of a solution by not knowing concentration [closed]

If I had a pH 10 in a 100ml solution of water and 93% sodium hydroxide how much mg/l of 93% sulfuric acid would we need to use to reach a pH of 4. From my dated college chem books and a lot of google ...
4
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1answer
442 views

pKa and pH graphically

I'm quite a newbie in chemistry and I'm trying to learn how logarithmic diagrams work. I have been told that you can calculate pKa and pH graphically: pKa, when [HA] = [A-] pH, when [H+] = [A-] Why ...
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1answer
332 views

What is the pKa of iodous acid?

Searching the web readily gives the $\mathrm{p}K_\mathrm{a}$ of hydroiodic acid, hypoiodous acid, and iodic acid, however, extensive searching did not result in any value of the $\mathrm{p}K_\mathrm{a}...
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1answer
204 views

Adding hydrogen ion concentration while calculating pH

I have just started learning how to calculate pH and I have noticed that adding [$\ce{H+}$] makes a negligible difference in few cases whereas in other cases it makes a major change in the final value....
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1answer
270 views

Why does the stability of ascorbic acid decrease (increased rate of oxidation to dehydroascorbic acid) when pH increases?

I am doing a Chemistry IA on the stability of ascorbic acid in different pH, and found that the stability decreased (there was a lower final concentration of ascorbic acid) as pH increases. Why is ...
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1answer
2k views

Carbonic acid in water [closed]

If we add a weak acid such as carbonic acid in water it weakly dissociates to form bicarbonate and hydrogen ions . Now water already has some hydrogen ions, having a ph=7. So now indirectly we ...
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2answers
834 views

Why does adding salt to water reduce the pH?

I recently heard someone claim that adding table salt to vinegar caused HCl to form which helped them clean coins - clearly not the case - however I thought I'd disprove it by doing an experiment. So ...
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2answers
592 views

Does solubility of acetic acid depend on the pH?

Does the solubility of acetic acid increase or decrease in water if I adjust the pH? Conversely, a water-insoluble molecule (like retinol), can its solubility be increased by adjustment of the pH? I ...
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0answers
67 views

pOH listed as basic?

In a solution, the pOH value is 8.95. You are asked to evaluate whether the solution is an acid, a base, or neutral solution. If the pOH is 8.95, then the pH is ...
6
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3answers
15k views

If you add AlCl3 to water, why does the pH decrease?

You are not adding any hydrogen ions, so why does the pH of the solution decrease? Thank you in advance. EDIT: I will add the context of my asking this question to clarify some details. This is not ...
6
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1answer
3k views

Why does gaseous HCl not change dry blue litmus paper to red?

I am doing a practical in lab, in which HCl is to be evolved. I found that when blue litmus is near the evolved gas, it doesn't turn red. But, when litmus is dipped in water and then brought near the ...
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2answers
2k views

Finding pH after dilution?

Assume that $\ce{pKa}$ is 4.76 Mix $\pu{50 mL}$ of $\pu{0.1M}$ $\ce{HA}$ and $\pu{50 mL}$ $\pu{0.1M}$ $\ce{NaA}$. This is solution (i). Calculate concentrations of $\ce{HA}$ and $\ce{A-}$, ...
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735 views

How to Prepare a 80mL Carbonic Acid-Bicarbonate buffer solution of ph=7.4 in laboratory? [closed]

I have the following materials which I can use: 0.1 M sodium bicarbonate solution Sodium Bicarbonate powder 0.1 M HCL Distilled Water Universal Indicator It will be a great help if you can provide ...
1
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1answer
137 views

Measuring pH using pH paper makes solution change color

I have an unknown substance dissolved in water, and it's milky white. When I put in a pH paper, the paper shows that it is slightly basic at pH ~8. However, after putting in the pH paper, the solution ...
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3answers
705 views

How do I calculate the pH of this buffered solution?

Calculate the $\mathrm{pH}$ of a buffered solution containing $\pu{0.5 M}$ ammonia and $\pu{0.5 M}$ ammonium chloride when $\pu{0.15 M}$ $\ce{HCl}$ is added into it. The $\mathrm{p}K_\mathrm{b}$ of ...
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0answers
288 views

What is the pH of a solution that results of a mixture of two others with known pH?

Solution A has a pH of 1, soultion B has a pH of 6. If I mix the same volume V of each solution into one, what will be the pH of the resulting solution? I'm guessing here as no more information has ...
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1answer
1k views

Calculations for making a buffer from a weak base and strong acid

How many moles of $\ce{HCl}$ must be added to $\pu{100 ml}$ of a $\pu{0.100 M}$ solution of methylamine ($\mathrm pK_\mathrm b = 3.36$) to give a buffer having a $\mathrm{pH}$ of $10.00$? (The answer ...
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0answers
364 views

Calculating the pH of soft drink [closed]

Me and my classmates are doing an experiment in order to determine the pH of Sprite. We are going to conduct a titration with NaOH. We are taking under consideration that the citric acid in Sprite is ...
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2answers
1k views

pH probe bulb - what is happening within the glass?

I am trying to understand how the glass bulb of a pH electrode of a pH meter works - the glass bulb itself. Not the reference electrode or the rest of the electrode (HCl, Ag/AgCl wire, etc...), the ...
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1answer
1k views

Effect of pH on positive and negative charges of a zwitterion

I read that the isoionic point is defined as the pH at which a zwitterion molecule has an equal number of positive and negative charges and no adherent ionic species. I have two questions ...
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1answer
326 views

How to make a buffer using HClO

If we plan to prepare a buffer with the $\mathrm{pH}$ of $7.35$ using $\ce{HClO}$ ($\mathrm pK_\mathrm a = 7.54$), what mass of the solid sodium salt of the conjugate base is needed to make this ...
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2answers
83 views

Why is only one part of buffer in the reactants side?

Given that buffers consist of either a weak acid and its basic salt, or a weak base and its acidic salt and that the buffer consisting of CH3COONa and CH3COOH is added to water (H2O) ... The ...
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3answers
379 views

The effect of NaCl on the ability of an acid to protonate benzoate

I've been doing several experiments using soda to quantify the amounts of caffeine and benzoate. Because of our methods of analysis, we had to decarbonate our soda. The experiment offered two ways for ...
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0answers
87 views

How to calculate the gas-liquid interaction for dissolved HNO3 in water with air?

Thanks for reading this and (maybe) helping me in advance! I have to face the following problem: I have got $\ce{HNO3}$ dissolved in water (roughly $\pu{50\%}$) and I want to know how much $\ce{HNO3}...
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1answer
1k views

What effect does diluting a buffer have on its buffer capacity?

What effect does diluting a buffer have on its buffer capacity? I am not worried about the effect on the pH, just the buffer capacity.
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1answer
69 views

Why aren't extremely dilute acid solutions basic in nature? [duplicate]

Lets say we prepare a solution of $\ce{HCl}$ with a concentration of $\mathrm{10^{-8}}$. Even on full dissociation (which it will, because it is a strong acid), the $\ce{H+}$ ion concentration due to ...
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1answer
263 views

How would one correct for a blank in a potentiometric titration?

I want to do a potentiometric titration with perchloric acid of a sample consisting of active drug (weak base) and two other components. Based on theory, I already know that these two other components ...
5
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1answer
7k views

Difference in pH of water and rainwater

In my textbook (Olmsted and Williams 4th ed) it is given that pH of pure water is 7, pH of unpolluted rain water is between 5-6 and pH of acid rain is between 4-5. It is obvious that pH for acid ...
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0answers
28 views

Help with idea for an optical ph sensor

I am experimenting at home with the idea of making an optical ph sensor that can read the colour of ph indicator using photodiodes. I am wondering if there is some kind of ion permeable membrane ...
2
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1answer
582 views

How to find the moles of carbonic acid I need to add to make a solution of KOH acidic

I wanted to know if it is possible to add enough carbonic acid to a $\ce{KOH}$ solution to make it an acidic solution. The $\mathrm{pH}$ of my KOH solution was $13.2$. After adding $\pu{50 g}$ of ...
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1answer
115 views

How can I calculate the pH of the solution created by reacting sodium with water?

$\pu{23mg}$ of sodium was added to $\pu{100cm3}$ of water. What is the pH of the solution produced? $$\ce{2Na + 2H2O -> H2 + 2NaOH}$$ So firstly to find the moles, I've divided $\pu{0....
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1answer
240 views

The safety of homemade slime

Disclaimer: I am not a chemist, but I figured this may be the place to ask. So, recently, there has been a lot of news going around about the homemade slime burning a child's hands and I got curious ...
4
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1answer
287 views

Relationship between the water ionization constant and ionic strength

I read in a textbook that the water ionization constant ($K_\mathrm{w}$) increases as the ionic strength of the solution increases and it confused me. If the ionic strength increased, then the ...
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0answers
76 views

How to slow/prevent corrosion of a steel post

I have a steel post set in limestone, about 18-20 inches deep, with some concrete around it. I just noticed that I have about 6 inches of water inside the post. The limestone had a small seam in it ...
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0answers
451 views

How does increasing ionic strength affect the pH of solution?

I'm having trouble interpreting the data for an experiment. With increasing ionic strength, I found lower solubility but also lower pH of the solution. What is the effect of the ionic strength on the ...
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1answer
388 views

How to calculate volume for NaOH and drano max gel (includes dilution and pH, pOH)

I have a question on an assignment that I don't quite understand. It says: What volume of $\pu{0.0100 mol/L}$ $\ce{NaOH(aq)}$ would have the same number of moles of hydroxide ions as $\pu{100.00 ...
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2answers
850 views

Relating pH and buffer capacity

So, here is the equation for a weak acid - strong base pH curve And here is the expression gotten when the derivative of concentration of hydronium ions with respect to volume of base added is ...
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4answers
2k views

Change in pH when boiling off acidic water

Assume 1 L of deionized water at pH 2 at ambient pressure open to atmosphere. I boil off 500 mL. I believe the pH will not change because to the same extend as water boils off it will also boil off H+ ...
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1answer
257 views

The Sørensen pH scale and strong acids diltution from pH 1 to pH 4 by 1000 times?

I am reading a chemistry book that makes the following point about Sørensen's pH discovery regarding [H+] being in negative powers of 10: To dilute a solution from a pH 1 to a pH 4 (just 3 pH ...
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1answer
499 views

Why is the inside of a cell both more acidic and more negative than its environment?

In a very simplistic way of thinking, an acidic solution has more positively charged $\ce{H+}$ ions present, whereas a basic solution has more negatively charged $\ce{OH-}$ ions present. Can that be ...
4
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1answer
176 views

What is the pH of kvass?

I know that it is less than 7.0, but would be nice to know exact value of pH of natural fermented kvass (not soda-like counterfeit). Another aspect is to know if kvass is more gentle than Cola (pH=2.5)...
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0answers
397 views

pH versus absorbance

So, as part of a project, comparing theoretical and experimental pH curves for a strong acid and a strong base, I need to measure absorbance and express it in terms of pH. This is because we don't ...
2
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1answer
914 views

Measuring or calculating the pH of 4M NaOH? I prepared the solution in Milli Q water

I prepared $4\ \mathrm{M}$ solution of $\ce{NaOH}$, and the glass electrode I use cannot measure it the $\mathrm{pH}$ correctly. What are the other options do I have to exactly know the solution's $\...
5
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2answers
6k views

Calculation of the pH of a mixture of a strong acid and weak acid

The question is to find out the $\mathrm{pH}$ of a mixture of weak acid and strong acid. My book just states the formula as $$\mathrm{pH}=-\log \frac{C_2+\sqrt{C_2^2+4K_\mathrm{a}C_1}}{2}$$ where $...
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0answers
144 views

In the graph provided, which of the substances is the most efficient in acting as an antacid?

If every dot represents the addition of 0.1 g of the respective base. I suppose that the best would be the one that reaches the highest pH, in the shortest time, for example Calcium Carbonate, but if ...
5
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2answers
1k views

Which salt will best be able to buffer the addition of HCl?

From these three salts, which will be best able to buffer the addition of $\ce{HCl}$? ammonium chloride sodium carbonate ammonium acetate. I think sodium carbonate is the right choice ...
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189 views

How can you perform an acid-base titration with antacids if substances, like aluminium hydroxide, are insoluble?

I am trying to perform an experiment in order to determine the efficiency of different antacids. An online search later shows that you add an HCl solution in a solution created with a base/antacid. ...