All Questions
Tagged with acid-base experimental-chemistry
124
questions
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Trends in pKb for both acetic acid and water
I am trying to rationalise a result that I have recently measured in the lab. I'm measuring the pKb of different compounds in anhydrous acetic acid, using the procedure outlined in this paper (https://...
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7
votes
2
answers
642
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Question about the differences of white and grey NaH properties
We are having some problems with the next reaction in our lab. As you can see, is the sulfonylation of an indole in which we use NaH (60% dispersion in mineral oil) as a base. This reaction goes with ...
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-2
votes
3
answers
674
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Can pure hydronium exist?
Can pure hydronium exist? If not, why not? It seems to me (and I am no chemistry expert) like pure hydronium should have the theoretical maximum acidity or minimum pH that a substance can reach.
Can't,...
2
votes
1
answer
272
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pKa and pKb in solvents other than water
I know that when you have aqueous solutions, then the pKa and the pKb are linked to each other (pKa + pKb = 14). Is there an equivalent relationship between pKa and pKb in non aqueous environments? I'...
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1
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0
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365
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Can I use a mechanical pipette to transfer strong acid?
I am an undergraduate student majoring in physics. I am looking for the best method to accurately measure the volume of strong acids like hydrobromic $(w(\ce{HBr(aq)}) = 48\,\%)$ and hydroiodic $(w(\...
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0
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0
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62
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Why does the pH of very strong NaOH solutions not make sense? [duplicate]
I'm wondering why the pH of extreme alkaline solutions, such as the case with $\pu{10 M}$ $\ce{NaOH}$ does not make practical sense and I'm wondering why this is the case? Refer to my calculations ...
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165
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Why is the pH of this ammonia solution more acidic than another ammonia solution?
I made two similar ammonia solutions in different ways, and they resulted in different pH, but i'm not sure why.
Solution 1
Added 5.84 g NaCl to a 500 mL flask. Then added 10 mL 25% ammonia solution. ...
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7
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2
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1k
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Mechanism of the blue bottle experiment
I have researched multiple mechanisms for this experiment yet all of them suggest different versions or are too vague. None of them are consistent since the final overall equation seems to be missing ...
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2
votes
1
answer
117
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Difference between change of enthalpy of neutralization between copper and manganese carbonate
I was doing a calorimetry experiment to calculate the change in enthalpy during neutralization reactions between metal carbonates and hydrochloric acid. I experimented with 5 metal carbonates: ...
1
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0
answers
416
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How useful is thymol blue (acid) as an indicator?
The pH range of thymol blue (acid) is 1.2-2.8.. This pH range seems pretty useless. Generally, the sudden change in pH for SA-SB titration occurs in the range of 4-10; the sudden change in pH for SA-...
- 201
6
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67
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How to make a thin layer of crystalline barium titanate on copper substrate?
Is it possible to create a thin $\ce{BaTiO3}$ crystal layer on a copper plate by putting the plate in a beaker, pouring in heated hydrofluoric acid that has been saturated with $\ce{BaTiO3}$ powder ...
-1
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1
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106
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What is the product of the following reaction(different sources give different answers) [closed]
$$\ce{FeS +dil HNO3}$$
$$\ce{FeS +conc HNO3}$$
I got different answers to these reactions in different sources
Source1 Jd lee:
Source 2 Op Tandon:
Can anyone please explain which is the correct one ...
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-1
votes
1
answer
106
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Will concentration of sodium hydroxide affect the result of chicken feather hydrolyzate if i don't standardized it?
The title of the paper:
Isolation and characterization of keratin from chicken feathers https://doi.org/10.1063/5.0002792
Here is the method:
Keratin was isolated by dissolving 5g of chicken feather ...
- 79
20
votes
2
answers
3k
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Why is carbonic acid often ignored?
Water (distilled or not) picks up CO2 from the atmosphere, some of which dissolves to form carbonic acid (H2CO3), lowering the pH by a point or two.
From that it seems like carbonic acid would be the ...
- 1,172
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2
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1k
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Can ferrous ions exist in an acidic solution?
Can Fe2+ ions exist in an acidic solution or will they always pick up available protons and become Fe3+? My hunch is they can't exist but I'm not really sure.
If the latter, does that mean that ...
- 1,172
0
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2
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194
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What might cause overestimated measured pH value of sodium hydroxide solution pumped with carbon dioxide?
I tried an experiment at home where I had a $\ce{CO2}$ tank pumping $\ce{CO2}$ into a solution of $\pu{28 g}$ sodium hydroxide in $\pu{200 ml}$ water. The initial $\mathrm{pH}$ was $11.24.$
I expected ...
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1
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1
answer
969
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NaOH + atmospheric CO2: Unexpected results troubleshooting
I've conducted an experiment where a solution of $\pu{4.2 M}$ $\ce{NaOH}$ was left exposed to atmospheric $\ce{CO2}$ for a period of time and titrated using potentiometric titration and potassium ...
- 111
2
votes
1
answer
156
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How to Test Auto-Ionization of Ammonia
I was wondering how we could test that the auto-ionization of liquid ammonia actually occurs experimentally. The chemical equation is described below:
$\ce{NH_3 <=> NH_4^+ + NH_2^-}$
I was ...
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-1
votes
1
answer
49
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I have contradictory results in a research paper, how do I proceed with my analysis?
I am performing a simple acid-base titration investigating the efficency of different pure antacid compounds, and in my results, I found out that NaHCO3 neutralized the fastest (using a pH by time ...
0
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1
answer
271
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Why are some weak acid equilibrium approximations invalid in very dilute solutions?
Using two approximations for the dissociation of a weak acid, we can write
$$K_\mathrm{a}= \frac{[\ce{H+(aq)}]^2}{[\ce{HA(aq)}]}$$
One of these two approximations we use is that the concentration of ...
- 209
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2
answers
3k
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Effect of dilution on weak acids pH [closed]
My textbook has a question which says what would happen to the pH of a weak acid if it is diluted with water. The answer is its pH would decrease.
My teacher’s argument is that it would indeed ...
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0
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33
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Weak acid titration curve [duplicate]
At the beginning of a weak acid titration curve (when titrated with a strong base), there is a sharp increase of pH before it levels out more due to the buffer solution that will occur. But why is ...
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3
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1
answer
69
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Difference in titration curves
In my titration curve for HCl being titrated with NaOH, the initial pH-value was plotted as 2.1 according to a pH-meter. When I found the equivalence point and calculated the concentration of HCl, it ...
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-1
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2
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221
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Can a weak acid react to give a stronger acid? [closed]
I was trying to understand why $\ce{AgCl}$ does not dissolve in $\ce{HNO3}$ and the reaction I could think of was something like this:
$$\ce{AgCl + HNO3->AgNO3 + HCl}$$
I could not understand why ...
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-4
votes
2
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94
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Acid boric preparation [closed]
Is there a simple reaction to yield boric acid ($\ce{H3BO3}$) from boron trifluoride ($\ce{BF3}$)?
-2
votes
2
answers
465
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How Do I Determine The Strength Of Two Ammonia Solutions Using Titration Methods? [closed]
Two housewives disagreed on the strength of an ammonium cleaning agent. Housewife A thought that her brand was more effective than the brand used by housewife B. Plan and design an experiment that ...
- 3
0
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0
answers
31
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Order of adding reactants on growth of Cu
I am reading the following paper which details the steps to control growth of Copper. They fabricate Copper powders from $\ce{CuNO3, NaOH, and C6H8O6}$. Specifically, in this paper they add the sodium ...
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4
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447
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Why is the experimental pH of vinegar (acetic acid) so much higher than expected?
I bought some sodium hydroxide on Amazon and went about titrating solutions I make with it.
As I'm an amateur chemist at home, I have limited tools. A pad of paper, some 5% acetic acid vinegar, and ...
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1
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569
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What is the relative rate of diffusion of ammonia to hydrogen chloride, both in gaseous states? [closed]
I encountered this problem during an assignment:
I answered it as C, but the assignment grader marked it as wrong and indicated that A is correct.
I asked another instructor about it and gave me a ...
-6
votes
1
answer
266
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what catalyst to use for the reaction between AgNO3 and NaCl? [closed]
What is the best catalyst to use for the reaction between AgNO3 and NaCl that would result in a change in activation of energy so therefore more precipitate formed. Please give me the ways I can ...
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1
answer
280
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How can I make AgNO3 more basic? [closed]
Is there anything that I can add to the AgNO3 solution that will make it more basic without forming a precipitate such as reacting with OH or HCl?
Please be more specific and give an example.
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2
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0
answers
444
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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....
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1
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1
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102
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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 ...
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17
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1
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10k
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Neutralizing a sulfuric acid spill
From my AP Chem Prep Book:
What should you do if you spill sulfuric acid on the countertop?
A) Neutralize the acid with vinegar.
B) Sprinkle solid NaOH on the spill.
C) Neutralize the acid with ...
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2
votes
1
answer
2k
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Acid-base titration: Unknown base in burette or flask?
While finding the concentration of $\ce{NaOH}$ via titration with $\pu{0.05M}$ Oxalic acid solution (in our lab) we put NaOH in the burette whereas added phenolphthalein to oxalic acid in titration ...
user84548
-1
votes
1
answer
1k
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Titration/ Separating Soluble Salts/ NaHSO4
When performing titration between NaOH and H2SO4, both Na2SO4 and NaHSO4 are formed (both are soluble in water), is there any method to obtain crystals of NaHSO4? (Maybe by separating two soluble ...
1
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0
answers
45
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How do you purify phosphoric acid from cheap commercial (hardware-store) products?
I am looking for idea's on how to purify phosphoric acid for lab use, as the the price for reagent grade V's home-use ended with me buying a product designed as a rust-killer for steel... The ...
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2
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1
answer
155
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Can antimony pentafluoride be made by adding hydrogen fluoride to antimony trifluoride?
I was looking at how the strongest acid was made and I found something I did not understand. On the Wikipedia page for antimony trifluoride it shows the production of $\ce{SbF3}$ using $\ce{HF}$:
$$\...
- 173
2
votes
1
answer
415
views
Can I use litmus paper to test unknown liquid that contains a concentrated strong acid?
Can I use litmus paper to test unknown liquid that contains a concentrated strong acid (example $\ce{H2SO4}$)? Can concentrated strong acid destroy litmus paper?
- 75
1
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1
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511
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Will strong concentrated acid destroy litmus paper and pH paper if they are dipped in acid?
I am curious to know what will happen if I have litmus paper and pH paper, and I dip them into strong concentrated acid like conc. $\ce{H2SO4}$ to test its acidity or basicity. Will acid destroy ...
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1
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1
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63
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Could this solution be resolved by titration?
I have a mixture of $\ce{NH_4NO_3}$ and $\ce{NH_3}$ at $\ce{pH}$ of about 13.
It is possible to determine the concentration of both on them by acid-base titration?
I was told it's possible, and that ...
user78790
2
votes
1
answer
2k
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Does hydrochloric acid change in concentration over time?
I have new bottles of 1 N hydrochloric acid from Fisher. The acid comes standardized from the company:
Standardized at 25 °C to pH 8.2 against sodium hydroxide that has been standardized against ...
- 151
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0
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298
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How can I dissolve photography film?
I am looking to completely dissolve negative film strips. Acetone was my first try and did not work. If anyone knows/ or has any ideas i would be so greatful.
-1
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1
answer
3k
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How to confirm a powder is Sodium Hydroxide?
Long-story-short, my mother found a bag of white powder with some soap making supplies. We're about 90% sure it's powdered lye, but I thought it would be fun to confirm this somehow.
Is there a way ...
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0
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1
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1k
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Steps of crystallization
An excess of copper(II) oxide is added to dilute sulfuric acid to make crystals of hydrated copper(II) sulfate.
The processes listed may be used to obtain crystals of hydrated copper(II) sulfate.
...
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5
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3
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3k
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Why isn't my galvanic cell making enough voltage?
I'm in kind of a pickle here. I made a galvanic cell of Lead and aluminium for a chemistry internal assessment but unfortunately, it didn't turn out so well and neither me nor my teacher has any clue ...
-2
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1
answer
567
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How to standardise NaOH? [closed]
My aim is to "To determine the concentration of citric acid in lemon juice using titration technique." and as following i need to standardise the NaOH in order to titrate it with validity. Is there a ...
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5
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2
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340
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Should the tip of the burette of an automatic titrator be immersed in the analyte?
In all the tutorials I found online, the tip of the burette (containing the titrant - NaOH) was immersed into the analyte solution. My question is: shouldn't the tip be out of the solution? Isn't ...
- 151
10
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4
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8k
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What is the real pKa of water?
What is the $\text{p}K_\text{a}$ of water? A simple google search yields the value $15.74$, but this site and this paper say it's $14.0$.
According to my understanding, the correct answer should be $...
- 601
1
vote
1
answer
6k
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How do I make a 0.5 M citrate buffer at pH 4.5?
I need to make a citrate-sodium citrate buffer at 0.5 M concentration and pH 4.5. I calculated the molarities of the citrate and disodium citrate based on the Henderson Hasselbalch equation, using a p�...
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