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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Dependency of dissociation of acid on pH of solution and pKa [on hold]
When pH of solution is higher than the pKa of the acid, it will largely exist as its conjugate base.
I cannot get why is it so.
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How to find the pH for a very diluted HCl solution? [duplicate]
Yesterday my chemistry professor asked us to try to solve this problem.
Find the pH of this reaction: $$\ce{HCl + H2O -> H3O^+ + Cl^-}$$
Knowing that:
The volume of the solution is 1 liter.
...
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1answer
20 views
Why must a buffer solution contain both a weak acid and a salt solution of its conjugate base?
Doesn’t the weak acid dissociate to produce the conjugate base on its own?
I understand that when a strong base is added to the buffer solution, the hydroxide ions will react with the hydrogen ions ...
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1answer
18 views
How to calculate the amount of citric acid that would be necessary to replace sulfuric acid in an electroplating solution? [on hold]
Before anything, I must tell you that I have almost no knowledge in chemistry so please forgive my ignorance in the topic.
I'm currently working with copper electroplating and I'm in the process of ...
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0answers
18 views
Does temperature decrease with an increase in pH? [on hold]
If you increase the pH of a solution, will its temperature decrease?
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Adjusting pH of phosphate buffer [closed]
I would like to calculate the amount of $\ce{HCl}$ required to change the pH of a stock solution of phosphate buffer solution that already has sodium bicarbonate from 7.2 to 6.8. How should this be ...
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0answers
23 views
Find concentrations of Sodium Acetate and Acetic Acid to create buffer solution [closed]
The stockroom contains 1M $\ce{NaOAc}$ (Sodium Acetate), 1M $\ce{CH3COOH}$ (Acetic Acid), distilled water, and strong acids and bases. You need to create a buffer solution that has a pH of 4.75 such ...
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3answers
4k views
Sugar solutions have a neutral pH in themselves, but it makes your body acidic. Why? [closed]
I'm not an expert, but as far as I understood a sugar solution is completely neutral since sugar can't take hydrogen ions out of the water or donate them in. Sugar is a non ionic compound, so it does ...
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1answer
117 views
Optimum pH range for formation of Schiff bases
What is the optimum range of pH for the formation of Schiff Bases by the addition of hydroxylamine to an aldehyde or a ketone?
According to Peter Sykes' A Guidebook to Mechanisms in Organic Chemistry,...
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1answer
26 views
Regarding acid-base reactions, how does one know when a hydrophobic base substance is fully protonated?
When there's a weak base substance (hydrophobic powder), and it needs to be completely protonated by adding an acid (eg: HCl), how does one know when it's completely protonated? Since the powdered ...
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Charge of nucleosides at 7.3 p
I am looking for electric charge values of adenine ($\ce{C5H5N5}$), cytosine ($\ce{C4H5N3O}$), thymine ($\ce{C5H6N2O2}$), guanine ($\ce{C5H5N5O}$) and uracil ($\ce{C4H4N2O2}$) at $\mathrm{pH} = 7.3$ ...
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Seeming discrepancy between pKa and corresponding Ka of methylamine
The first entry in PubChem for the $\mathrm pK_\mathrm a$ of methylamine is $10.657$ at $25\ \mathrm{^\circ C}$. My elementary understanding is that this would be found as the negative log of the $K_\...
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41 views
Understanding how the definitions of pH and activity are compatible
At $T=\pu{25 ^\circ C}$ and $P=\pu{1bar}$, the density of water is $\pu{0.997 kg L-1}$.
Neglecting nonideality of the mixture $\ce{H2O(l), H+}$ and $\ce{OH-}$ (all activity coefficients are close to $...
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1answer
38 views
Experimental determination of pH [closed]
I am trying to determine the experimental pKa for two weak acids that were titrated against 0.20M NaOH.
I have read elsewhere that you can take the point where the graph becomes steep and divide the ...
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2answers
63 views
When an acid is added to water, why does the hydroxide ion concentration decrease?
At equilibrium in pure water, we have
$$\ce{[H_3O+][OH-]} = 10^{-14}$$
Since $\ce{H3O+}$ and $\ce{OH-}$ ions are produced in pairs, we may conclude
$$\ce{[H_3O+]}=\ce{[OH-]} = 10^{-7}$$
So far so ...
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1answer
15 views
What are standard controllers for automatic pH control?
My background in control theory comes from electrical engineering (robots, motors, etc.) and I want to build a control system for automatic pH control.
Can I directly apply my knowledge from ...
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1answer
37 views
neutralization of a strong acid with a strong base [closed]
When a 1M H2SO4 is mixed with an equal volume of 1M NaOH, is the mixture acidic, basic, or neutral?
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1answer
36 views
How do I calculate the amount of polyprotic acid and base needed to achieve a certain buffer pH?
e.g. Citric Acid and Trisodium Citrate
$\ce{H3C6H5O7 <=>[ka_1] H2C6H5O7- + H+ <=>[ka_2] HC6H5O7^2- + H+ <=>[ka_3] C6H5O7^3- + H+}$
Using the definition of Ka and substituting for ...
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2answers
32 views
Does a solution of pH zero contain hydroxide ions? [closed]
Are there hydroxide ions in a solution of pH 0?
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1answer
107 views
Calculate mass concentration of Ca(OH)2 solution
Can anyone help me calculate the mass concentration of $\ce{Ca(OH)2}$ solution with molar mass $\pu{74.1 g/mol}$ at the $\pu{pH of 12.8}$.
My work so far:
From the pH I get the molar concentration ...
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1answer
47 views
pH throughout a titration
Estimate the $\ce{pH}$ of the solution that results when $\ce{75.0 mL}$ of $\ce{0.275 M HCl}$ is added to $\ce{50.0 mL}$ of $\ce{0.275 M Na2HPO4 (aq)}$.
My book gives the successive $\ce{Ka}$ values ...
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1answer
85 views
Why doesn't pH = pKa1 in the buffer zone for this titration?
Below is an image from my textbook representing the titration curve for the titration of $5.00\ \mathrm{mL}$ of $0.010\ \mathrm M$ $\ce{H2S2O3}$ with $0.010\ \mathrm M$ $\ce{KOH}$, which has $\mathrm ...
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1answer
33 views
Acid neutralization [closed]
I am working on a biogas plant,
digester volume 3000 liter,
right now pH condition is acidic at 4.00
my requirement is to maintain pH to 6.50 to 7.20
what should I do?
some suggestions are there like, ...
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0answers
36 views
Water values and water hardness
We have drinking water with the following values:
Calcium mg/l 62.7
Magnesium mg/l 10.3
total hardness 7.) dH 11.1
Total hardness 7) mmol/l CaCO3 1,99
Carbonate hardness °dH 8.5
...
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0answers
83 views
How to measure pH of deionized water
reverse osmosis deionized water (RODI) is used to rinse acid off silicon after it undergoes silicon etching. Sample of water is taken and measured by using pH meter. However, pH meter takes a 1-2 ...
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0answers
15 views
EQPt pH of a Monoprotic Acid-Base Titration: Product of Molarites Over Their Sum
Context
The Henderson-Hasselbalch equation is as follows. $$pH=-\log\big(K_a\big)+\log\bigg(\frac{[A^-]}{[HA]}\bigg)$$ One may follow its derivation in order to understand how it came to be, yet ...
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1answer
47 views
Confusion About Acid/Bases That Don’t Follow the Arrhenius Definition [closed]
I understand that acidity is merely a reflection of how many free hydrogen ions are in water, and basisicity is just a reflection of the number of hydroxide ions, but I don’t understand how this ...
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1answer
221 views
How to calculate pH of the Na2Co3 solution given ambiguous Ka values
This is the exact question i faced on exam.
Calculate the pH of $\pu{0.05 M}\ \ce{Na2CO3}\ (\ce{H2CO3}: K_\mathrm{a,1}= 4\times 10^{-7},\ K_\mathrm{a,2}= 4.7\times 10^{-11})$
Solution
$\ce{Na2CO3 -&...
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If Ti(NO3)4 is dissolved in water, what would be the change of pH?
Does this compound exist in nature. I would suppose the salt would dissolve in it's ions (Nitrate and $\ce{Ti+}$). Wouldn't the nitrate react with the hydrogen in the water and give us a acid? And ...
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2answers
224 views
Calculate pH of a weak acid and weak base neutralization reaction
I'm an industrial pharmacist needing some help with some chemistry basics.
I'm trying to calculate the theoretical pH of an effervescent preparation containing 2 mmol citric acid ($\ce{H3C6H5O7}$), 4 ...
3
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1answer
74 views
What is the pH of this H2SO4 solution? [duplicate]
I'm trying to solve a simple problem which is driving me crazy. It says:
Estimate the pH of a solution that contains 1 gram of $\ce{H_2SO_4}$ dissolved in 1 liter of water.
When I solve the ...
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0answers
55 views
Calculating the pH of a weak acid from the Kb of its conjugate base
I'd start off by saying it's been many years since I was in chemistry lessons and have forgotten much, but recently I have had to relearn a lot of basic chemistry. The following doesn't really impede ...
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2answers
255 views
The effect of pH and solubility on coagulation in water treatment
In water treatment, a specific pH range must be met in order for the process of coagulation to occur properly. Sources have stated this is due to the pH affecting the solubility of the coagulant, but ...
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36 views
Capacity of buffer
I want to dissolve 23 mg of EDC (N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride) in MES buffer with pH=6. How can I know the amount and concentration of MES buffer which can keep the pH=...
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1answer
39 views
Working out pH of solution when excess NaOH is added
In a pH titration, $30\text{cm}^3$ of $\ce{NaOH}$ is added to $\pu{20 cm3}$ $\ce{CH3COOH}$. The concentrations of both solutions was $\pu{0.5 mol dm-3}$. $K_\mathrm{a} = \pu{1.7 x 10^{-5}}$ for $\ce{...
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1answer
194 views
Finding the pH value of HF [closed]
Find the pH value of HF.
$pH = -\log[H+]$ for strong acids
$pOH = -\log[OH-]$ for strong bases
$pH = 1/2(pKa - \log C)$ for weak acid
$pOH = 1/2(pKb - \log C)$ for weak base
HF is weak acid so $...
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1answer
71 views
Safely lowering bleach pH without chlorine gas?
According to Eurekalert, by lowering the pH of household bleach (e.g., by adding vinegar or citric acid), we can increase $\text{[HOCl]}$ and consequently greatly improve the disinfecting capabilites ...
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1answer
180 views
What is the pH of starch?
We need to identify an unknown for a chemistry lab. It's either starch or zinc sulfate.
We know that zinc sulfate is acidic, but what is the pH of starch?
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1answer
2k views
Finding pKa from equivalence point on titration curve [closed]
Is there a mathematical proof/explanation of why $\mathrm{p}K_\mathrm{a}$ corresponds to the $\mathrm{pH}$ at $\text{Volume of titrant}/2$ at the equivalence point?
A concise proof will suffice.
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0answers
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Buffer solutions
So my understanding of buffer solutions is that when a strong acid is added, it will react with the conjugate base to convert the strong acid to a weak acid. The weak acid then dissociates to reform ...
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1answer
231 views
Calculating PH of solution after adding strong acid (equilibrium)
Consider the classic example when talking about acids and bases:
Say you have 1M of $\ce{HCL}$ and you throw it into water, calculate the resulting pH (= concentration of $\ce{H3O+}$).
The way this ...
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1answer
75 views
Determining volume of acid needed to be added to reach a specific pH
Suppose there are $\pu{0.024}$ moles of $\ce{Na2HPO4}$ in a $\pu{0.250L}$ solution. How would we calculate the amount of $\pu{0.145M}$ $\ce{HCl}$ needed to reach a $\mathrm{pH}$ of 6.60?
I have ...
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1answer
97 views
Find the concentration of proton after adding a acid to NaOH [closed]
I have this simple problem that I cannot figure out though, only the first part.
100 ml of 1.0 $\frac{mol}{L}$ $NaOH_(aq)$ contains ( a ) g of NaOH.
After mixing 100 ml of 1.0 $\frac{mol}{L}$ $...
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1answer
70 views
What mass of potassium lactate is needed to 300.0 mL of 0.238 M Lactic acid solution to make a solution with a pH of 4.00? pKa (lactic acid) =3.86
Upon attempt, I've yielded an answer of 11.91g. My calculations do not take 300 mL Lactic acid solution into account, and now I somewhat know the error is at least partially due to the fact that my ...
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1answer
1k views
pH value of HF, hydrogen fluoride or hydrofluoric acid?
I've been looking for a source but I find different results when I try looking for an answer to this.
I'm looking for weight percentages of 1 to 10% HF (~0.5 to ~5.1M) and what their pH values are.
...
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0answers
31 views
Buffer/ Indicators / % protonated
I have a buffer with a pH of 5. First I need to find what indicator to use. My options are (Thymol Blue - $\mathrm{p}K_\mathrm{a} = 8.9$), (Bromothymol Blue- $\mathrm{p}K_\mathrm{a} = 7.1$), or (...
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2answers
629 views
How do I find the theoretical pH of a buffer solution after HCl and NaOH were added, separately?
This question is about the theoretical pH of a buffer solution.
Calculate the theoretical pH values expected for a $\pu{200mL}$ buffer solution containing a 1:1 ratio of acetic acid and sodium ...
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1answer
270 views
What happens to a quaternary ammonium cation at a pH above its pKa?
I am working with a lipid and I have firm reasons to believe that its pKa is around 8. This lipid is a cationic lipid where the nitrogen is a quaternary amine with two lipid chains and two methyl ...
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0answers
395 views
Calculating the pH of a solution of sodium carbonate
I've seen similar questions on this site, but I'm having trouble as my book said something else. For a $\pu{0.09989 M}$ solution of $\ce{Na2CO3}$, my book said:
$$\ce{Na2CO3 + 2H2O -> H2CO3 + 2Na+ ...
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2answers
825 views
Does salinity affect seawater's pH?
If so, how? It seems like excessive salinity within seawater has the same destructive effect on marine organisms just like excessive acidity. But in real terms, is there any relation between salinity ...
