Questions tagged [buffer]
Use for questions regarding solutions containing a mixture of a strong acid and weak base or vice versa.
73
questions
-3
votes
1
answer
47
views
NaHCO3/ H2CO3 buffer [closed]
In a classic Na2CO3 + HCl titration, what is the buffer that forms?
Is it NaHCO3 / H2CO3 ? isn't H2CO3 unstable, won't it just deprotonate?
Is the buffer NaHCO3 / HCO3- ? If so, how can this be a ...
- 1
-3
votes
0
answers
19
views
Can certain buffer solution prevent an effective electrolysis of CuSO4? [closed]
for an experiment that I am planning in school, I want to test the effect that changing the pH of a CuSO4 solution has on the efficiency of electrolysis, measured by monitoring copper deposition on ...
- 1
2
votes
0
answers
60
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 ...
- 81
2
votes
2
answers
51
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 ...
- 51
-4
votes
1
answer
56
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 (+) + ...
- 1
-2
votes
1
answer
61
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 ...
- 33
-2
votes
1
answer
49
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 ...
4
votes
1
answer
259
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 ...
1
vote
0
answers
117
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 ...
- 11
-1
votes
1
answer
118
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 ...
- 127
-3
votes
1
answer
72
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 ...
user131254
0
votes
0
answers
74
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 ...
- 11
3
votes
0
answers
57
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 ...
0
votes
1
answer
73
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
...
- 235
4
votes
2
answers
280
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 ...
- 151
0
votes
0
answers
58
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 ...
- 11
0
votes
0
answers
38
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 ...
- 21
3
votes
1
answer
251
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 ...
- 39k
-2
votes
1
answer
38
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 ...
- 163
0
votes
1
answer
689
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, ...
-3
votes
1
answer
73
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 ...
- 11
0
votes
0
answers
62
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....
- 27
0
votes
2
answers
50
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 ...
- 11
0
votes
0
answers
62
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 ...
- 109
0
votes
0
answers
871
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 ...
- 71
1
vote
0
answers
50
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 ...
- 129
0
votes
0
answers
101
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 ...
- 151
1
vote
0
answers
452
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 ...
- 11
0
votes
1
answer
567
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 ...
- 103
-1
votes
1
answer
556
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 ...
- 119
-1
votes
1
answer
81
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 ...
1
vote
0
answers
68
views
How do two species from the same buffer system have different pKa values? [closed]
$$
\begin{array}{lr}
\hline
\text{Reagent}~(\pu{0.1 M}~\text{solutions}) & \mathrm{p}K_\mathrm{a} \\
\hline
\text{Ammonia} & 9.25 \\
\text{Acetic acid} & 4.75 \\
\text{Ammonium chloride} &...
- 19
0
votes
1
answer
109
views
How exactly does a buffer made up of a weak acid and its conjugate base work upon addition of hydroxide ions? [duplicate]
Consider a buffer solution containing a weak acid and its conjugate base ($c_\mathrm{total} = \pu{0.1 mol L-1}$):
$$\ce{HA <=> H^+ + A^-}$$
When $\ce{H+}$ ions are added (from a strong acid), ...
- 553
-5
votes
1
answer
38
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 ...
- 1
1
vote
0
answers
56
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_\...
- 1,409
2
votes
2
answers
176
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}$ ...
- 302
-1
votes
1
answer
58
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 ...
- 191
0
votes
0
answers
98
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{...
- 1
0
votes
2
answers
616
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 ...
- 153
9
votes
2
answers
819
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 ...
- 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}$.
- 1
-1
votes
1
answer
407
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 ...
-4
votes
1
answer
509
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{...
- 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}$...
- 19
5
votes
0
answers
177
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}$ ...
- 151
0
votes
1
answer
81
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{...
1
vote
2
answers
267
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 ...
- 111
2
votes
2
answers
5k
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, ...
- 29
3
votes
2
answers
482
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 $\mathrm{pH}$ ...
-2
votes
1
answer
2k
views
How to change pH of CuSO4?
I'm currently very desperate to know this. I'm doing an experiment about adsorption/chelation of Cu ions in CuSO4 using banana peels using the UV-Visible spectroscopy. How do I change the pH of 0.1M ...
- 134