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Questions tagged [buffer]

Use for questions regarding solutions containing a mixture of a strong acid and weak base or vice versa.

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How to (numerically) model a phosphoric acid titration curve

I've been learning how to simulate a 1M phosphoric acid titration curve using numerical methods in R. So far has this has been the best curve: Notice how it flattens out (artificially) towards the ...
Naiky's user avatar
  • 133
8 votes
3 answers
4k views

Solubility Product and Buffers

The ionization constant of benzoic acid is $6.46 \times 10^{-5}$ and solubility product for silver benzoate is $2.5 \times 10^{-13}$. How many times silver benzoate is more soluble in a buffer of $\...
user avatar
5 votes
3 answers
3k views

Am I understanding buffering capacity against strong acid/base correctly?

I just want to make sure I'm understanding buffering capacity correctly. I've been working on this problem: Suppose you have an acetic acid buffer, $\mathrm{p}K_\mathrm{a} = 4.74$, at the ...
Axioms's user avatar
  • 153
5 votes
0 answers
184 views

What pH value of 1M sodium crotonate solution supposed to be?

I need to prepare the $\pu{1M}$ solution of sodium crotonate, however, I don't have one in lab, but I do have sodium hydroxide and crotonic acid. Thus, I calculated that for $\pu{100 mL}$ of $\pu{1M}$ ...
Araneus0390's user avatar
4 votes
2 answers
385 views

Why does "bis-tris propane" have two pKa values?

Wikipedia gives two pKa values for "Bis-tris propane". What about bis-tris-propane gives this compound two pKa values where other compounds have only one? How am I to choose which pKa value ...
Nicholas DeMarco's user avatar
4 votes
3 answers
11k views

What's the effect of temperature on buffering capacity?

I did some research online but I still couldn't get any conclusion. Some said that the buffering capacity decreases when temperature increases because of the increase in ionisation of the weak acid ...
Sammy's user avatar
  • 41
4 votes
1 answer
267 views

What is the math behind the formula for the concentration of the strong titrant when calculating theoretical buffer capacity of a diprotic system?

I have a question related to finding the theoretical buffer capacity of a diprotic system, specifically about the formula for the concentration of the strong titrant. In this post: What is the formula ...
ToastyBananas's user avatar
3 votes
2 answers
677 views

Finding final pH of the buffer solution without applying Henderson equation

A is beaker with $\pu{0.1 M}$ $\pu{25 cm^3}$ solution of $\ce{NH3}.$ B is beaker with $\pu{0.1 M}$ $\pu{5 cm^3}$ $\ce{HCl}.$ Now the solution of A and B is mixed. What will be the final $\mathrm{pH}$ ...
Sadatul islam Sadi's user avatar
3 votes
2 answers
7k views

How to Prepare a Buffer Solution?

Problem I am given the task of preparing three buffer solutions at pH $10$, $9.5$, and $9.0$ . I have available concentrated ammonia and $\pu{3M}$ hydrochloric acid. The buffer capacity desired is $\...
hotmaildotcom1's user avatar
3 votes
1 answer
471 views

What happens when you add a weak acid to a solution buffered at a pH of 8.0?

There are a lot of textbook examples showing what happens to the pH of a buffered solution when you add strong acids and strong bases. Searching for an example calculation where you add weak acids or ...
Karsten's user avatar
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3 votes
3 answers
8k views

Finding is the concentration of H⁺ in a benzoate buffer solution after adding HCl

Q: A buffer with a $\mathrm{pH}$ of 4.44 contains $\pu{0.21 M}$ of sodium benzoate and $\pu{0.12 M}$ of benzoic acid. What is the concentration of $\ce{[H+]}$ in the solution after the addition of $\...
chemstudent's user avatar
3 votes
1 answer
92 views

Relative levels of the two most prominant glutamate species at pH 4.7

Calculate the relative levels (i.e. ratios of concentrations) of the two most prominant glutamate species at pH 4.7. I know that the Henderson–Hasselbalch equation is to be used which is $$\mathrm{pH=...
Macy's user avatar
  • 41
3 votes
1 answer
2k views

Calculation of pH in diluted buffer

I have been preparing $\pu{150 mM}$ and $\pu{30 mM}$ Tris Buffers (pKa=8.3). Using .15 M solutions of both Tris and Tris-HCL. Here is the information in which I have calculated theoretical pH values ...
jpa317's user avatar
  • 31
3 votes
0 answers
28 views

Assessing stability of protein used for interaction experiments after changing buffer from tris to HEPES

I have a protein with a theoretical $\mathrm{pI}~9.0$ currently stored in $\pu{25 mM}$ tris and $\pu{250 mM}$ $\ce{NaCl}$ $(\mathrm{pH}~8)$ at $\pu{−80 °C}.$ I need to do experiments in HEPES at $\...
TheChemist's user avatar
3 votes
0 answers
75 views

Measuring [A-]/[HA-] with Buffer and Indicator

I'm very confused on how to calculate the [A-]/[HA] value, given the fact that my dilution series uses buffers at various pH values with the same indicator (supplied at the same concentration to each ...
Tyler Anderson's user avatar
2 votes
1 answer
233 views

Effects when 100 mmol NaHCO3 are mixed with 50 mmol HCl

I read somewhere that when $\pu{100 mmol}\ \ce{NaHCO3}$ are mixed with $\pu{50 mmol}\ \ce{HCl}$, a buffer arises. I'm confused, since $\ce{HCl}$ is a strong acid, and I thought the classic buffer is ...
chsimmons1's user avatar
2 votes
1 answer
948 views

What is total concentration of buffer used in derivation of buffer capacity?

ChemBuddy — The buffer capacity provides the following: $$\ce{HA <=> H+ + A-}$$ Total concentration of the buffer $c_\mathrm{buf}$ is given by $$c_\mathrm{buf} = [\ce{HA}] + [\ce{A-}]\tag{19.3}$...
Aditya Dev's user avatar
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2 votes
2 answers
64 views

Calculating the pH after adding hydrochloric acid to the potassium hydrogen phosphate solution

I am trying to calculate the $\mathrm{pH}$ of a solution obtained by mixing $\pu{20.00 mL}$ of $\pu{0.2 M}$ potassium hydrogen phosphate solution and $\pu{10.00 mL}$ of $\pu{0.25 M}$ hydrochloric acid ...
crvenikupus's user avatar
2 votes
2 answers
2k views

Can I make a buffer with a weak acid without adding it's conjugated base, when the desired pH of the solution is exactly the pKa of the weak acid?

An acid will be 50% dissociated when the solution it's in have a pH equal to the acid pKa ('afirmation 1', for later reference). We also know that a good buffer solution have equal concentrations of ...
d.J's user avatar
  • 21
2 votes
1 answer
4k views

How to calculate ionic strength of zwitterionic buffers?

Using the formula for the molar ionic strength from Wikipedia — Ionic strength $$I = \frac 1 2\sum_{i = 1}^nc_iz_i^2,$$ I have calculated that $\pu{0.1 M}$ of HEPES $(\ce{C8H18N2O4S})$ would have a ...
user2679447's user avatar
2 votes
2 answers
193 views

Finding the pOH of a buffer from the scratch without the Henderson Hasselbalch equation

I found this question on the internet that said: Find the pOH of the solution obtained by mixing $\pu{0.1 mol}$ of $\mathrm{NH_4 OH}$ $(K_\mathrm b = 10^{-5})$ and $\pu{0.1 mol}$ of $\ce{(NH4)2SO4}$ ...
Floatoss's user avatar
  • 302
2 votes
2 answers
7k views

Preparation of ammonium acetate buffer for HPLC

Buffer solutions are typically prepared by dissolving an appropriate salt in water and then adjusting the $\mathrm{pH}$ to the desired position by addition of the conjugate acid or base. For example, ...
user103231's user avatar
2 votes
1 answer
277 views

Finding new pH after adding potassium hydroxide to citrate buffer

Calculate the $\mathrm{pH}$ change of citrate buffer containing $\pu{10.26 mmol}$ of citric acid and $\pu{6.98 mmol}$ citrate caused by adding $\pu{4.72 mmol}$ of potassium hydroxide. $\mathrm{p}K_\...
Dima's user avatar
  • 21
2 votes
1 answer
5k views

How many moles NH4Cl must be added to NH3 to create buffer with pH=9?

How many moles of $\ce{NH4Cl}$ must be added to $\pu{2.0 L}$ of $\pu{0.10 M}$ $\ce{NH3}$ to form a buffer with $\mathrm{pH}=9$? Assume the addition does not change the volume of the solution ...
math_lover's user avatar
  • 1,398
2 votes
0 answers
49 views

Stability of n-Dodecyl-beta-D-maltoside in buffer solutions for assay experiments

I have a buffer system which contains multiple salts and in addition DTT and n-Dodecyl-beta-D-maltoside. I understand that DTT is hydrolysing quite fast and this component must be used always fresh ...
raptorlane's user avatar
2 votes
0 answers
82 views

Why do buffer solution only maintain pH to a certain limit?

I know that buffers have a capacity after which they are not able to maintain a relatively stable pH. This capacity is exceeded when we add too much acid or base but I was wondering why does this ...
Spluesh's user avatar
  • 83
2 votes
0 answers
417 views

How to determine the pH of citrate buffer system

I used this table (http://microscopy.berkeley.edu/Resources/instruction/buffers.html) to make a citrate buffer system. The Pka value is 6.4, and I multiplied the solution by ten to make a larger batch....
Rae Ann's user avatar
  • 59
1 vote
1 answer
11k views

How to calculate bicarbonate and carbonate from total alkalinity [closed]

It's been a long time since I did my chemistry classes and I'm currently trying to analyze groundwater samples for hydrogeology purposes. I would like to evaluate carbonate and bicarbonate ...
Rachel's user avatar
  • 51
1 vote
1 answer
100 views

Why does Calcium (specifically Calcium Carbonate) inhibit the Citrate buffer system?

Is it because citrate chelates calcium and then is unable to react with other chemicals being added? If so can someone explain this reaction to me, or if not provide what the reason is? If anyone has ...
Rae Ann's user avatar
  • 59
1 vote
1 answer
30 views

Dihydrogenphosphate and hydrogenphosphate buffer solution

I have just come across a problem involving a buffer solution comprising of dihydrogenphosphate ions and hydrogen phosphate ions, which asks how the mixture of these two ions can function as a buffer ...
Quin Gardiner Bax's user avatar
1 vote
2 answers
334 views

Confusion regarding the mechanism of acidic/basic buffer solutions

While learning about acidic and basic buffer solutions we were told that they can resist pH change if we add small amounts of acid or base by neutralizing the $\ce{H+}$/$\ce{OH-}$ ions from the added ...
ErrorEliminator's user avatar
1 vote
0 answers
189 views

Exact calculation of pH of diprotic acid plus strong base

Another post has an excellent "exact" calculation for the [H+] (or pH) of a generic diprotic acid dissociating in water. Combining acid dissociation constants to determine pH of diprotic ...
sb4's user avatar
  • 11
1 vote
0 answers
54 views

Can addition of a "neutral" salt like NaCl assist pH test strip measurement accuracy in low ionic strength/poorly buffered solutions?

After a web-search, it seems ISAs (Ionic Strength Adjusters) are offered commercially to assist pH electrode/probe measurements. Presumably meant to increase conductivity (without affecting pH ...
revans19's user avatar
  • 129
1 vote
0 answers
562 views

How strongly affected is the buffering capacity of sodium carbonate - sodium bicarbonate by temperature changes?

I would like to do a lab regarding the affects of temperature on the buffering capacity of sodium carbonate - sodium bicarbonate in particular for sulfuric acid. Currently I have two competing ...
naman1008's user avatar
1 vote
0 answers
83 views

How do two species from the same buffer system have different pKa values? [closed]

$$ \begin{array}{lr} \hline \text{Reagent}~(\pu{0.1 M}~\text{solutions}) & \mathrm{p}K_\mathrm{a} \\ \hline \text{Ammonia} & 9.25 \\ \text{Acetic acid} & 4.75 \\ \text{Ammonium chloride} &...
Sincaia's user avatar
  • 19
1 vote
0 answers
58 views

Buffer problem in polyprotic acids [duplicate]

I read a problem which was as follows: Equal volumes of $\pu{1M} \ \ce{H3PO4}$ and $\pu{1M} \ \ce{Na3PO4}$ are mixed. The $\mathrm{pH}$ of the resultant mixture is (along with this $K_\mathrm{a1}, K_\...
Ashish's user avatar
  • 1,409
1 vote
0 answers
2k views

Which is more effective at raising pH, Tums or baking soda?

Chemical buffers like Tums (calcium carbonate) and bases like baking soda (sodium bicarbonate) are both used medically to reduce acidity in the stomach to ease heartburn symptoms. I'm curious which is ...
TheEnvironmentalist's user avatar
1 vote
0 answers
942 views

Stable physiological buffer to make NAD+ solution

I was wondering what would be the most stable physiological buffer for nicotinamide adenine dinucleotide (NAD+), for potential storage as frozen aliquots - 6 months stability or around there would be ...
SimplyEngineered's user avatar
0 votes
2 answers
61 views

How to make NaxPO4 buffer?

I am currently trying to make a buffer for protein expression. According to the article, I am to use a buffer with $\pu{50 mM}$ $\ce{Na_{x}PO4}$, $\pu{pH 8}$ (and $\ce{0.5 M NaCl}$). How do I make the ...
Rie's user avatar
  • 11
0 votes
1 answer
715 views

pH of PBS after adding acetic acid

Why is there a need for pH adjustment below ? Can pH go below 4.3 after adding acetic acid to PBS ? “First prepare stock solution consisting of 50 ml of 10× PBS (pH 7.4), 12.5 ml of 80% glycerol, and ...
mete's user avatar
  • 103
0 votes
1 answer
119 views

How exactly does a buffer made up of a weak acid and its conjugate base work upon addition of hydroxide ions? [duplicate]

Consider a buffer solution containing a weak acid and its conjugate base ($c_\mathrm{total} = \pu{0.1 mol L-1}$): $$\ce{HA <=> H^+ + A^-}$$ When $\ce{H+}$ ions are added (from a strong acid), ...
Vulgar Mechanick's user avatar
0 votes
2 answers
781 views

Calculating the pH of a 'buffer' solution?

Question: Determine the $\mathrm{pH}$ of the solution resulting when $\pu{100 cm^3}$ of $\pu{0.50 mol dm-3}$ $\ce{CH2ClCOOH}$ is mixed with $\pu{200 cm^3}$ of $\pu{0.10 mol dm-3}$ $\ce{NaOH}$. The ...
vgupt's user avatar
  • 153
0 votes
1 answer
1k views

A method to create NH3-NH4Cl buffer solution using titration method

My aim is to create a basic buffer solution. I know that to create a basic buffer solution, we need a strong acid and weak base. In my case I have chosen $\ce{NH3}$ and $\ce{NH4Cl}$. Using titration, ...
Partth Kulkarni's user avatar
0 votes
2 answers
17k views

Calculating ratio of conjugate base and acid when pH and pKa are given

Buffer solutions are used by biological mammalian systems to maintain the $\mathrm{pH}$ of blood plasma within a narrow range. In these systems, the compound from which this solution is obtained is $\...
Liz's user avatar
  • 1
0 votes
1 answer
86 views

Question regarding chemical equilibrium when adding a salt to acid solution

Having read the following was wondering something: $$\mathrm {p}K_\mathrm{a} = -\log\frac{[\ce{H+}]_\mathrm{eq}[\ce{A-}]_\mathrm{eq}}{[\ce{HA}]_\mathrm{eq}} $$ $$\ce{HA <=> H+ + A-}$$ $$\mathrm{...
protectgoodlivingbeingask's user avatar
0 votes
0 answers
81 views

Does temperature affect ionic strength?

Hello I apologize if this is a dumb question but if I have a phosphate buffer made up of Na2HPO4 and NaH2PO4 and I gradually increase the temperature (lets say 10,20,30,40,50) what would happen to the ...
kio's user avatar
  • 11
0 votes
1 answer
75 views

Why doesn't the volume of NH3 = 325 ml in this problem? [closed]

I'm struggling with the problem below, and don't understand why A buffer solution with pH = 9.0 is to be prepared from a 0.2 M ammonia solution and a 0.15 M $\ce{HCl}$ solution. The sum of the molar ...
wengen's user avatar
  • 423
0 votes
0 answers
73 views

How to calculate the buffer capacity for polyprotic acids? specifically H2PO4 --- HPO42- + H30+

as the title says. Is b= amount of OH-/ H3O divided by volume of buffer x change in pH wrong to use with polyprotic acids? Can I calculate the buffering capacity of a sodium phosphate buffer made up ...
8675's user avatar
  • 11
0 votes
0 answers
39 views

Calculating acid volumes needed

I collect water quality samples used for irrigation. The samples are sent to a lab to measure $\ce{Ca^{2+}, Mg^{2+}, CO3^{2-}, HCO3^-}$, pH, and total dissolved solids. I need to use acid to prevent ...
sdabach's user avatar
  • 21
0 votes
0 answers
64 views

How to find pH for acetate buffer?

Calculate the pH of the solution that results when $\pu{40.0 mL}$ of $\pu{0.100 M}$ $\ce{CH3COOH}$ is mixed with $\pu{30.0 mL}$ of $\pu{0.200 M}$ $\ce{NaCH3COO}.$ $K_\mathrm{a}(\ce{CH3COOH}) = \pu{1....
Nori's user avatar
  • 27