Questions tagged [acid-base]
This tag should be applied to questions concerning acid and base reactions. An acid is capable of donating a hydron/ proton (Brønsted acid) or capable of forming a covalent bond with an electron pair (Lewis acid). A base on the other hand is a chemical species/ molecular entity having an available pair of electrons capable of forming a covalent bond with a hydron/ proton (Brønsted base) or with the vacant orbital of some other species (Lewis base).
2,754
questions
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Acid Dissociation [duplicate]
I have a small confusion
If suppose HA is a acid then , HA gives H+ and A- ions in water.
The presence of H+ implies that the solution is acidic.
OK fine... but I came across that this solution will ...
1
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1answer
71 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 $\ce{(NH4)2SO4}$ ...
1
vote
0answers
22 views
Why is ethanol, water and amonium needed for DMG to react with nickel?
I had this question on a test and I'm unsure on why ethanol is required for the reaction.
I understand that you need the ammonia and water to make oxonium ions needed for the reaction to occur.
We had ...
0
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0answers
43 views
pH for an HA/NaA solution using a contour map
The following question has troubled me for a while now.
A virtual weak acid $\ce{HA}$ dissociates as follows:
$\ce{HA <=> H^+ + A^-}$
with the acid dissociation constant $K_\mathrm{a} = 10^{-3....
2
votes
0answers
28 views
Titration of weak acid and strong base at low concentrations [duplicate]
Titration continues until one of the reactants (the one in conical flask) turns out to be a limiting agent as far as I know. From the titration of a weak acid and a strong base, I could learn that the ...
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votes
0answers
35 views
Acids give H+ in a reaction thus called reducing agent. But according to Lewis theory of acid and base, anything accepting pair of electron is acid [closed]
Now as acids accept electrons and so must be called oxidizing agent. and I feel it to be a bit contradicting. please clarify if any misconception
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0answers
17 views
How do I find the theoretical pH of a buffer solution? [closed]
A buffer solution is prepared via adding solution A (Sodium
dihydrogen phosphate 27.6 gm up to 1000mL distilled water) and
solution B (Disodium hydrogen phosphate 5.362gm up to 100mL
distilled water). ...
5
votes
1answer
168 views
Why is the aqueous solution of KMnO4 slightly basic?
This is in the context of the various changes in oxidation state the permangananate ion can undergo with the variation of the pH of the medium. Besides the cases of strongly basic and strongly acidic ...
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votes
0answers
23 views
Finding the number of moles in a buffer solution from pKa and pH values [closed]
Question:
The pKa of acetic acid, CH3COOH, is 4.74. A buffer solution was made
using an unspecified amount of acetic acid and 0.30 moles of NaOOCCH3
in enough water to make 2.00 L of solution. The pH ...
2
votes
0answers
44 views
Can't aluminium chloride do electrophilic substitution as an electrophile?
In halogenation reaction of benzene, $\ce{AlCl3}$ is used as a catalyst in order to form electrophile $\ce{E^+}$.
So I was wondering that $\ce{AlCl3}$ is a Lewis acid (that fact being also used in ...
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votes
0answers
15 views
pH scale is open ended [duplicate]
In most of the textbooks it is stated that pH scale lies between 0 and 14 but I found an article in which it is stated that pH scale is open ended https://pubs.acs.org/doi/pdf/10.1021/ed083p1465.But I ...
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votes
1answer
18 views
Increase in volume of solution in neutralization reaction and its effect on weak acid [closed]
If 100ml of 1M acetic acid and 20ml 0.01M NaOH is taken in a reaction medium,they will neutralize each other. I don't know for sure if this reaction is completely neutralized or not just took as an ...
6
votes
1answer
106 views
Comparing acidic strengths between benzylammonium ion and phenol
Question
Compare the acidic stengths between benzylammonium ion and phenol.
I first tried to remove the H+ ion from both of them and tried to compare the relative stabilities of resulting conjugate ...
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votes
0answers
19 views
Calculation of the concentration of CH3COOH in an acid-base solution with a given resulting pH [closed]
I had some trouble understanding how to calculate the concentration of acetic acid in this question:
What should be the concentration of 0.1 liter of CH3COOH to can obtain a pH of 6.8 after the acid-...
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votes
1answer
64 views
Equilibrium constant expression for an acid base reaction
While reading an organic chemistry textbook I saw the following Formula for calculating equilibrium constant of an acid-base reaction
Consider following acid base reaction in which $\ce{HA}$(reactant ...
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votes
1answer
38 views
pH of water after getting heated [duplicate]
When water is heated, the molecules of the water gain energy which leads to dissociation of water molecules. Does this means that pH of water has changed?
0
votes
1answer
29 views
Acidic nature comparison; benzoic acid and phenylacetic acid
The $\ce{pK_a}$ values of benzoic acid and phenylacetic acid are around 4.2 and 4.31 respectively.
In benzoic acid, you have the resonance being the dominating effect, destabilizing a conjugate base ...
2
votes
1answer
45 views
How to go about deciding the acidic strength of a functional group in an aromatic compound?
The question requires me to identify the decreasing order of the acidic strength of the following functional group. But I'm afraid I don't know how to distinguish one from the other since all the ...
8
votes
1answer
177 views
pH of an aqueous solution with acetic acid and sodium acetate
An aqueous solution of $\pu{1L}$ contains $\pu{0.2 mol}$ of acetic acid and $\pu{0.2 mol}$ of sodium acetate ($K_\mathrm{a} = 1.8 \times 10^{-5}$). Compute the $\mathrm{pH}$ .
I'm trying to help my ...
6
votes
2answers
128 views
What does acidity of para-alkyl substituted phenols depend on?
Problem
Arrange the following organic compounds in decreasing order of acidity.
Answer
Question
According to my knowledge the answer should be P, Q, R, S. As we proceed from P to S we are ...
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votes
1answer
58 views
What happens if you add pure food grade lactic acid to fresh pasteurized milk? [closed]
What happens if you add pure food grade lactic acid that is free of bacteria to fresh pasteurized milk? What chemical reactions would take place? What does it taste like straight after mixing and a ...
2
votes
0answers
24 views
About the acidity of Sultiame [closed]
Why is sulthiam base even hough sulfur can accept the electron by resonance from nitrogen
like carbonyl group do?
0
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0answers
36 views
About the acidity of phenytoin
Can you explain why phenitoin is weak acid even though nitrogen is base?
Does carbonyl group always make structure acid?
If this structure doesn't have carbonyl group, would it be base not acid?
0
votes
1answer
114 views
Does sour milk have something else in it besides lactic acid that gives it such a horrific taste and odor?
Even slightly sour milk has a horrible, nauseating taste, while plain yogurt tastes either great, or at least nowhere near as bad. A dozen sources (all of them) say that the sour odor and taste of ...
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votes
0answers
35 views
Why does citrulline have two pka values?
Can someone explain to me why citrulline has two pka values? It has a carboxy group that could donate a proton, but where would the second proton come from? Should the amide group not be more basic ...
1
vote
0answers
42 views
Can PTFE be dissolved by aqua regia? [duplicate]
At the moment I am cleaning crucibels in aqua regia. I was wondering, whether I could stir it with a standard PTFE stirring bar or not?
I am not sure if it is needed or if the normal flactuation in ...
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votes
0answers
124 views
How do I make slightly sour milk palatable again?
Once in a long while I don't consume a carton of milk quickly enough and the remainder goes off and becomes slightly sour.
Is there a way that I make it taste nice again so I can enjoy drinking it or ...
0
votes
0answers
21 views
Total concentration conversion
when dealing with waste water and the total values of P, N, C are given in ppm units, what molecular weight is used for converting from ppm to molar?
for Example- what will be 12 ppm of P(T) in Molar ...
1
vote
2answers
75 views
Why is degree of dissociation used to estimate strength of an acid?
Problem
Which of the following will give strength of acid?
A) pH
B) Normality
C) Degree of dissociation
D) Dissociation constant
Answer
Question
If pH is not considered as a metric to assess the ...
1
vote
1answer
25 views
More ions form pairs when concentration of acid increases, does that decrease the speed of reaction?
Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of ...
2
votes
0answers
21 views
High kinetic basicity of alkoxides compared to alkyls
I'm reading something at the moment where they state:
This reagent has enhanced basicity as it benefits from the high kinetic basicity of alkoxides compared to alkyls.
This is in the context of ...
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1answer
59 views
Why do terminal alkynes have lower pKa values than non-terminal alkynes?
We were asked in class which have the lower $\mathrm{p}K_\mathrm{a}$ values: terminal alkynes or non-terminal alkynes. The teacher told that terminal alkynes have the lowest $\mathrm{p}K_\mathrm{a}$ ...
1
vote
1answer
73 views
Titration of multi-basic acid [closed]
How would a solution made of $\pu{20 mL}$ of $\ce{NaOH}$, $\pu{10 mL}$ of $\ce{HCl}$, $\pu{10 mL}$ $\ce{NaH2PO4}$ and $\pu{5 mL}$ of $\ce{Na3PO4}$, all of them in a concentration of $\pu{10 mmol/L}$, ...
5
votes
1answer
77 views
How is the hydrazone formed in the Wolff-Kishner reduction?
In the Wolff-Kishner reduction the first step is to react a carbonyl with hydrazine to form a hydrazone. The later steps of the reaction requires a strong base to cause loss of nitrogen.
However, the ...
0
votes
0answers
69 views
Why is Ka of weak acid increasing while being diluted?
I am calculating $K_\mathrm{a}$ and percent dissociation of acetic acid being diluted to $\pu{1.00 \times 10^{-1} M}$, $\pu{1.00 \times 10^{-2} M}$, and $\pu{1.00 \times 10^{-4} M}$.
The $\mathrm{pH}$ ...
0
votes
0answers
33 views
Why can indicator pKa be less than the pH at equivalence?
An indicator usually has a pH at equivalence tolerance range around its pKa value that is suitable for titration. However, if the pH at equivalence exceeds the indicator's pKa, wouldn't most of the ...
4
votes
1answer
67 views
Reason for triphenyl methane being less acidic than acetylene
This question came through answering a question that talked about the acidic order of four compounds.
Upon researching the actual $\mathrm p K_\mathrm a$ values I noticed that even though there was a ...
0
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0answers
29 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{...
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votes
1answer
53 views
Notation for inclusion of water in a dissolution equation
Earlier I had a student come by wanting to know how to show the dissolution of $\ce{NH4OH}$ in water. I would think we would just write it: $$\ce{NH4OH(aq) <=> NH3(aq) + H2O(l)}$$ I say this as $...
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0answers
46 views
Calculate concentrations of ions after acid-base reaction given volumes and concentrations
A $\pu{35.0 mL}$ of $\pu{4000 ppm}$ $\ce{HCl}$ solution is mixed with $\pu{45.0 mL}$ of $\pu{0.1025M}$ $\ce{NaOH}$ solution. Assume volumes are additive.
$$\ce{NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(...
5
votes
1answer
1k views
Can you meassure a negative pH value with a pH meter?
I was checking the $\mathrm{pH}$ of $\pu{1 M}$ chromic acid solution, and I got its $\mathrm{pH}$ around -1.7. Yet, $\mathrm{pH}$ of $\pu{0.4 M}$ solution was around -0.6. Could these values be ...
0
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0answers
16 views
Saponification - Oil and Alcohol?
I've been reading that a saponification reaction typically involves NaOH or KOH. I was wondering - could anything that contains an OH group cause a saponification reaction? For instance, coconut oil + ...
0
votes
2answers
78 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 ...
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votes
1answer
63 views
Finding a Mistake Calculating the pH of Ammonium Acetate
I'm trying to calculate the $\mathrm{pH}$ of a $\pu{0.10 M}$ solution of ammonium acetate, and I am struggling to find what mistake I am making within the following calculations:
We know that $\dfrac{[...
3
votes
0answers
36 views
Reactivity of unsaturated organolithium compounds
I'm particularly looking in the context of alkyl lithiums compared to vinyl-lithiums and alkynyl-lithiums.
Why is it that shifting from sp3 to sp2, and even further to sp carbanions, reduces the ...
0
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1answer
85 views
“HBr is donating a proton to LiOH”: Why doesn't it produce LiOH2?
In the section Brønsted-Lowry acid and base theory from Khan Academy:
In the reaction $\ce{LiOH(aq) + HBr(aq) -> H2O(l) + LiBr(aq)}$, $\ce{HBr}$ is donating a proton to $\ce{LiOH}$, thus acting as ...
4
votes
1answer
64 views
How do acids prevent ferrous sulfate from getting oxidised?
If $\ce{FeSO4.7H2O}$ is dissolved in an acidic environment, for example in 0.05 M aqueous solutions of methanoic or ethanoic acid, would that prevent it from getting oxidized if an oxidizing agent ...
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0answers
49 views
Possibility of removing two water molecules from glycerol
Not a chemist, but from a chemical formula perspective, how hard would it be to create acetone by acidifying glycerol?
$$\ce{C3H8O3 + 2 H+ <=> C3H6O + 2 H2O}$$
Has anyone ever heard of this ...
1
vote
0answers
75 views
Why is 2-fluorobenzoic acid more acidic than 4-fluorobenzoic acid despite its intramolecular hydrogen bonding?
I was reading about $\mathrm{p}K_\mathrm{a}$ values of 2-fluorobenzoic acid and 4-fluorobenzoic acid and found that the latter had a higher value which was surprising to me. I think that ...
1
vote
0answers
45 views
Why is oxalic acid more acidic than benzoic acid?
I came across this fact while reading my book and was confused. Looking at the structures, I had the intuition that benzoic acid would be more acidic as the conjugate base formed will resonate all ...
