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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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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
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
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
3 answers
298 views

Why are buffer solutions not neutral

I am very confused about buffer solutions and I have lots of ideas about them which don’t integrate together so I really can’t tell which are correct and which are wrong. That being the case it’s ...
QuantumHamster'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
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
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
-4 votes
1 answer
81 views

What happens to the ions after dissociation in an aqueous solution? [closed]

I'm in high school studying about Buffer Solutions. We had an example of a solution made up of Ammonium Hydroxide and Ammonium Chloride for a Basic Buffer. NH4OH ⇌ NH4 (+) + OH(-) NH4Cl ⇌ NH4 (+) + ...
Mel's user avatar
  • 1
-2 votes
1 answer
86 views

Calculate the pH of a buffered solution after adding strong acid [closed]

Calculate the pH of a solution formed by the addition of $0.0020$ moles of $\ce{HCl}$ to $\pu{100.0 mL}$ of $\pu{0.200 M}$ $\ce{CH3NH2}$/ $\ce{0.100 M CH3NH3Cl}$. $K_\mathrm{b}(\ce{CH3NH2})=4.4\times ...
Shoes's user avatar
  • 33
-2 votes
1 answer
104 views

Sodium Citrate / Sodium Phosphate Buffer Calculations

I'm trying to work through the calculations of a specific paper (linked here / below) but, my numbers are way off and I can't get them to match for the life of me. I need to make the same buffer but ...
user136195's user avatar
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
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 votes
1 answer
140 views

pH and degree of dissociation of drugs

I have a doubt, i hope not so stupid. Suppose we consider a buffer solution of acetic acid/acetate at pH = pKa = 4.76 and we add aspirin (pKa = 3.5): given that the pH of the solution is higher than ...
Luckenberg's user avatar
-3 votes
1 answer
85 views

What is the charge of amino acid in alkaline conditions?

This problem refers to the protein buffer in a living system. "If the blood pH becomes alkaline, there is a release of a proton from the $\ce{NH3+}$ ion, which takes the $\ce{NH2}$ form." I ...
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
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
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
4 votes
2 answers
386 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
0 votes
0 answers
74 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
3 votes
1 answer
473 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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-2 votes
1 answer
39 views

Will the solid formed after dehydration of a disodium hydrogen phosphate + sodium hydroxide solution be hygroscopic at STP?

Given a solution consisting of disodium hydrogen phosphate + sodium hydroxide (approaching a pH of 12), will the solid formed after dehydration of the solution be hygroscopic at STP? Which salts are ...
John Chris's user avatar
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
-3 votes
1 answer
81 views

pH calculation of a mixure containing 2 strong acids and a buffer mixture

Calculate the pH of a mixtureof 10 mL 0,1 M HCl ; 5 mL 0,1 M HNO3 ; 10 mL 0,2 M HAc ; 15 mL 0,4 M NaAc. My understanding was that I have to find the [H+] by: finding the concentration of the products ...
Jessica's user avatar
  • 11
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
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
0 answers
70 views

Finding dissolved amount of base from pH and solubility product

Calculate the amount of $\ce{Mg(OH)2}$ which is solubilized in $\pu{1.25 L}$ of a buffered solution at $\mathrm{pH} = 9.5$. $(K_\mathrm{sp}(\ce{Mg(OH)2}) = \pu{5.61E-12})$. From $\mathrm{pH}$ I ...
Rick88's user avatar
  • 109
0 votes
0 answers
1k views

How to calculate a citric acid and trisodium citrate buffer?

I am trying to calculate how to prepare 500 mL of a citric acid (H3Cit) and trisodium citrate (Na3Cit) buffer with a pH = 4.5 and a total concentration of 0.1 M. I know that it is necessary to use the ...
camibuidi's user avatar
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
0 votes
0 answers
128 views

How to estimate the pH of multi-component buffer (phosphate buffer in equilibrium with CO2 rich atmosphere)?

I wonder how the pH of buffer solution can be estimated if buffer consists of several systems in equilibrium to the gas phase. For example, (based on growth medium for one of the bacteria) buffer ...
Araneus0390's user avatar
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
0 votes
1 answer
721 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
-1 votes
1 answer
708 views

Prepairing a Sodium Acetate buffer - Meaning of molarity

We have instructions to prepare a "50 mM Sodium Acetate, pH 5 solution". I am not entirely sure what does the molarity refer to in this case. Does it mean: Add Sodium Acetate salt up to 50 ...
Keine's user avatar
  • 119
-1 votes
1 answer
91 views

How do buffers work? and why only solutions of a weak acid and its salt with a strong base or vice versa work as a buffer [closed]

Please note that the definition of a buffer in my textbook is given as The solutions which resist change in pH on dilution or with the addition of small amounts of acid and alkali are called Buffer ...
user869606'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
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
-5 votes
1 answer
39 views

buffer "recipe" needed [closed]

I have a question, that I hope can be answered without the respondant showing off how much they know about chemistry and talking in "words of art". It's been 50 years since I tool chemistry ...
Olen1009's user avatar
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
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
-1 votes
1 answer
62 views

titrating a weak acid with strong base in the present of buffer

I would like to get a neutral salt solution for a weak acid whose pKa is 3.42. This weak acid is in the form of solution (now is 20% w/w), thus I cannot directly dissolve the powder into the buffer ...
William Wong's user avatar
0 votes
0 answers
119 views

Given initial moles of weak acid, find moles of conjugate base to be added to get a final pH (volume unknown)

I am preparing notes on buffers and I came across this problem on a website: Given 10.0 mmol of a weak acid HA with $\textrm{p}K_a =5$, how many mmol of NaA needs to be added to have a final $\textrm{...
LDinCT's user avatar
  • 1
0 votes
2 answers
782 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
9 votes
2 answers
919 views

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
-2 votes
1 answer
1k views

Is mixture of ammonium hydroxide and ammonium nitrate a buffer solution? [closed]

Is a mixture of $\ce{NH4OH}$ and $\ce{NH4NO3}$ a buffer solution? I have seen some examples with $\ce{NH4OH}$ and $\ce{NH4Cl}$ but never $\ce{NH4NO3}$.
nichst7's user avatar
-1 votes
1 answer
498 views

How to calculate how much weak acid would dissociate in water?

So I know water has a pH of 7. If we add 0.1 mol of a strong acid inside 1 liter of water, it WILL fully dissociate into 0.1 mol of A- and 0.1 mol of H+ thus making the pH of the solution 1. But what ...
Bruno Machado's user avatar
-4 votes
1 answer
615 views

How to calculate pH of an CH3COOH solution? [closed]

please, does anyone know, how to properly (with calculation procedure) calcutate $\mathrm{pH}$ of an $\ce{CH3COOH}$, when you know only: -$\ce{CH3COOH}$ is 8% (water solution) -density of $\ce{...
HASHTAG's user avatar
  • 11
-2 votes
1 answer
1k views

Preparation of a HCN/NaCN buffer that has a pH of 9.8 and an osmotic pressure of 1.35 atm at 298 K

You are asked to prepare $\pu{2.0 L}$ of a $\ce{HCN/NaCN}$ buffer that has a $\mathrm{pH}$ of $9.8$ and an osmotic pressure of $\pu{1.35 atm}$ at $\pu{298 K}$. What masses of $\ce{HCN}$ and $\ce{NaCN}$...
user105739's user avatar
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
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
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