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).
2,277
questions
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0answers
13 views
What does acidifying a substance do?
For example, KMnO4 is acidified with sulfuric acid. Does the chemical properties of KMnO4 change or is there a reaction involved?
0
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0answers
17 views
Does the pKa value of synthetic indicators (e.g. phenolphthalein, methyl orange etc.) change across a range of temperatures? [on hold]
The temperature range I'm talking about here is between 20 degrees celsius to 90.
1
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0answers
11 views
Diketone intramolecular reaction question
I realize that one of the methyl groups on either carbonyl compound will become deprotonated and then it will attack the other carbonyl to form a pentane ring. However, with the methyl group in the ...
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0answers
30 views
What are the science concepts/processes in the reaction between hydrochloric acid and calcium carbonate? [on hold]
Can someone please explain the science behind this equation, in detail:
How and why is the water formed? How and why is the carbon dioxide formed? Is this an acid-base reaction? Is carbonic acid ...
-2
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0answers
16 views
In the picture below, which one is acidic, alkalalinse and neutral [on hold]
Which form do you think is present at acidic pH, which one in neutral solutions, and which one in alkaline solutions? Briefly justify your answers, based on the availability of protons at different pH ...
2
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0answers
53 views
Which is more basic: oxaziridine or diaziridine? [on hold]
Which is more basic: oxaziridine or diaziridine?
Oxaziridine's got one nitrogen and one oxygen as heteroatoms, while in diaziridine there are both nitrogens.
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0answers
29 views
Why at lower pH than pKa, acid doesn't dissociate to give H+ ions [closed]
I understand mathematically that pH lower than that of pKa, acid will be present in undissociated form but can anyone explain it qualitatively (logic) why it is so?
0
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0answers
30 views
What is the logic behind a 28% ammonia solution being labeled as 56.6% in ammonium hydroxide? [closed]
I assume it's just that the molecular mass is twice as large than ammonia's. Also, are we assuming 100% conversion in the reaction or not, given that's a weak base at 25C? This whole thing is kind of ...
0
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1answer
31 views
Negative hyperconjugation
Compare the acidity of the following compounds: $\ce{CF3OH}$ and $\ce{CCl3OH}$.
My attempt: according to me $\ce{CCl3}$ group will show a stronger Negative hyperconjugation effect than $\ce{CF3}$, ...
3
votes
1answer
104 views
Rechargeable Battery Based on Neutralization Reaction of Acid and Base [closed]
The neutralization reaction, such as $\ce{HCl + NaOH → NaCl + H2O}$, generates heat, which is around $\pu{57.30 kJ/mol}$.
Can we use this energy to design a battery?
This idea occurs in my mind for a ...
1
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1answer
52 views
How to determine pressure and concentration of carbon dioxide in blood plasma?
A man suffering from untreated diabetes mellitus is admitted to a hospital. Doctors fear that his blood $\mathrm{pH}$ may have dropped because of ketoacidosis. Analysis of his blood reveals that $[\ce{...
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votes
1answer
34 views
How can I prepare two phosphate buffer of different concentrations but give same pH? [closed]
How is it that buffers of different compositions can have the same pH? For example, it is possible to prepare 0.01 M phosphate buffer of pH 7.0 and 0.1 M phosphate buffer of pH 7.0? How?
I used ...
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votes
1answer
38 views
How to find the resist in pH change when both are same buffers of same concentration? [closed]
We are given two buffers [a) 0.1 M phosphate buffer of pH 7.7 and (b) 0.1 M phosphate buffer at pH 6.71 . If acid is to be added to the buffers, which of them, will resist the pH changes better
I ...
9
votes
2answers
794 views
What are the limitations of the Hendersson-Hasselbalch equation?
Our instructor told us that prior to the equivalence point, the $\mathrm{pH}$ of a solution is dependent on the HH equation. However, when I tried practicing for polyprotic acid titration, I came upon ...
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votes
1answer
47 views
Why do we need to use oxidation number in order to balance a complex chemical reaction easily in an acidic or alkaline medium? [closed]
I have been trying to balance this chemical reaction in an "acidic" medium without using oxidation number or ion electron method: [$\ce{Fe^2+ + Cr2O7^2- -> Cr^3+ + Fe^3+}$].
Though I can balance ...
1
vote
1answer
41 views
Why can Neutral Red (indicator) not test values below its pKa?
It is the only indicator I have found that does not test below its pka, and can't think of any reason for this.
Neutral Red has a pKa value of 6.8.
(
Reference 1,
Reference 2
),
but looking at its pH ...
0
votes
0answers
32 views
Why can't carboxylic acid + NaH + tert-butyl bromide react to create an ester?
So, the picture I showed above asks for which reagents can form the ester product. I was wondering why D can't form it? I was thinking that first, the $\ce{NaH}$ would react with the carboxylic acid ...
0
votes
1answer
35 views
Why is p-methoxyphenol less acidic than phenol?
They have slightly different $\mathrm{p}K_\mathrm{a}$ values of 9.9 (phenol) vs 10.2 (p-methoxyphenol).
They both have the same number of resonance structures too.
My guess is that the resonance ...
5
votes
1answer
55 views
Why does the tautomerism of purine favor 9H-purine? [duplicate]
I tried to explain the equilibrium by comparing the basicity of different nitrogen atoms in a purine anion, but I can’t see any obvious difference. Seems like that the 9-N will be the most basic ...
0
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0answers
28 views
Highly concentrated NaOH solution at high temperature vs borosilicate glassware and cellulose?
I've read here on stack-exchange that NaOH will react with glass through the following reaction:
4 NaOH + SiO2 ⤑ Na4SiO4 + 2 H2O
I would like to briefly heat a highly concentrated NaOH solution to ...
1
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0answers
20 views
Will a Lewis acid catalyze the reaction of HBr with primary alcohols?
It is well-established that a Lewis acid catalyst (popularly $\ce{ZnCl2})$ is necessary to form an alkyl chloride when reacting $\ce{HCl}$ with a primary alcohol. This actually changes the mechanism: ...
0
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1answer
59 views
Steric Inhibition of Resonance in ortho-substituted Benzoic Acids
It has been given that due to Steric Inhibition of Resonance (SIR), the acidity of ortho-substituted benzoic acid increases with respect to benzoic acid.
If this is the case then the conjugate base of ...
16
votes
1answer
627 views
What is the oxidation state of Mn in HMn(CO)5?
What is the oxidation state of $\ce{Mn}$ in $\ce{HMn(CO)5}$? If $\ce{H}$ has an oxidation state of $+1$, then $\ce{Mn}$ should have oxidation state of $-1$, which I'm not sure is possible.
On the ...
2
votes
0answers
30 views
Name of the intermediate in between phosphono and phosphonato group
$\ce{R-PO3^2-}$ is called a phoshonato group (https://www.ebi.ac.uk/chebi/searchId.do?chebiId=30931)
$\ce{R-PO3H2}$ is called a phosphono group (https://www.ebi.ac.uk/chebi/searchId.do?chebiId=48108)
...
0
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0answers
18 views
Acid Strength is paradoxical for me [duplicate]
First, let's take hidracids strength:
HI > HBr > HCl
That makes sense, the less electronegative the ametal is, less polar will be the molecule, thus, ametal is less attached to hydrogen and Oxygen ...
8
votes
1answer
302 views
Which is more basic: 1,2‐dihydropyridine or 1,4‐dihydropyridine?
Which compound is more basic of the two?
My thinking: In compound A, the lone pair of nitrogen are in resonance with two other double bonds. The resonance chain here seems to be longer as ...
1
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0answers
12 views
On what factors does the strength of an acid/base depends(temperature,concentration of an acid ,ionization extent)? [closed]
I would appreciate an answer in points not going too deep in the concepts (I am a beginner).
Thanks
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0answers
35 views
What is the acid dissociation constant of AgNO3?
What I'm trying to do is mix $AgNO_3$ and $HNO_3$ in water to make an acidic solution with a given pH value. Since the acidic dissociation constant of HNO3 is known ($p_{Ks}=-1.32 $ according to ...
14
votes
3answers
4k views
Why is it considered acid rain with pH <5.6?
I recently read in a book that rain is considered acid rain if the pH falls below 5.6. However a substance is acidic when the pH is below 7; so why is the boundary for acid rain 5.6?
I was thinking ...
0
votes
1answer
45 views
What kind of metal drums are used to store Hydrochloric Acid?
I would expect Hydrochloric Acid to be stored exclusively in glass or plastic containers, but I was surprised to find Honeywell offers it for sale in 30Kg metal drums (Link).
I think Hydrochloric ...
1
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0answers
46 views
Acidic character of hydroxy benzoic acid
Which is more acidic between salicylic acid and 2,6-dihydroxybenzoic acid? Please also explain the reason behind the same.
According to me, salicylic acid should be more acidic. Reason for that is ...
0
votes
2answers
69 views
Reactivity of boron towards acids
Boron is a non-metal, i.e. it accepts electrons and acids donate electrons, so boron should react with acid but it doesn't. Why?
1
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1answer
62 views
Oxidation of Vitamin C
How is ascorbic acid oxidized into dehydroascorbic acid? What is the reduction reaction in this case? Where are the 2 hydrogen atoms going?
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0answers
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Equilibrium constant when mixing HCl and NaOH
I have 300 ml of a 1 M $\ce{HCl}$ solution and 400 ml of a 1 M $\ce{NaOH}$ solution. These are now mixed at a constant pressure and a temperature of 25 °C.
The following neutralization reaction takes ...
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votes
2answers
52 views
Why is the hydroxide ion not considered to be amphoteric [closed]
Why is the hydroxide ion not considered to be amphoteric.
Why is $$\ce{2OH- <<=> H2O + O^{2-} }$$ not considered ??
Even though the equilibrium would mostly lie towards the left but still ...
1
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1answer
45 views
How a titration curve is affected when a poorly soluble salt is formed?
Suppose that I have $\pu{100 mL}$ solution of strong acid, $\ce{HA}$, at $\pu{0.10 mol L^{-1}}$.
This solution is titrated with a strong base solution, $\ce{BOH}$, at $\pu{0.10 mol L^{-1}}$.
Suppose ...
-1
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0answers
18 views
Acidity of ethanal vs propyne
I want to compare the acidities of
1)terminal hydrogen of propyne
2)hydrogen bonded to the sp3 carbon in propyne
3)alpha hydrogen of ethanal.
My idea is that the terminal hydrogen of propyne is ...
2
votes
0answers
19 views
How to control pH in a fermenter based on the acid produced by mircoorganism
I have got a bioreactor with an aqueous medium which produces biomass (yeast; S.cerevisiae) after inoculation.
I am observing and collecting data over the whole process via probes/etc. on different ...
1
vote
3answers
109 views
Is Ammonia (NH3) base?
In my text book, it is written that $\ce{NH3}$ is a base. They mentioned the reason for this is that it produces $\ce{OH-}$ ions in water. They stated this reaction:
$\ce{NH3 + H2O -> NH4OH}$
...
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votes
2answers
59 views
Finding the pH of the solution
In this video, at 3:30 min professor solves two equations
$$\ce{H2O —> H+ + OH-}$$
and
$$ \ce{HCl —> H+ + Cl-}$$
and deduces $[\ce{H+}] = [\ce{Cl-}] +[\ce{OH-}]$. How come this happen from ...
0
votes
0answers
35 views
Why is solubility of AgCN is higher in acidic buffer?
Solubility of $\ce{AgCN}$ is maximum in
A) Acidic buffer solution
B) Basic buffer solution
C) Pure water
According to me, it should not matter in which solution we are putting the $\ce{AgCN}$...
0
votes
1answer
63 views
Is this reaction possible? [duplicate]
When mixing HCl with K2CO3, the reaction that is usually given is the following:
K2CO3 + 2HCl → 2KCl + CO2 + H2O
I am wondering, however, if I could produce KHCO3 from K2CO3, by using half as many ...
0
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0answers
25 views
Thermodynamics of Acid Base Neutralisation
I was attempting an exam in which they questioned us about the thermodynamics of acid-base reaction.
The question was this:
In neutralisation reaction of a strong acid and a strong base in a ...
0
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0answers
37 views
Is xylene an acid?
What is the pH of xylene, and is it considered to be a corrosive substance?
Specifically I am interested in how xylene might interact with electrical conductors and components, which contain copper, ...
0
votes
1answer
55 views
What is the heat of reaction of weak acid reacting with weak base compared to strong acid reacting with strong base? [closed]
My book has this line only that "weak acid and weak base reaction will produce lesser heat than constant enthalpy" of strong acid and strong base neutralization which is $\pu{-57.3 kJ/mol}$.
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votes
1answer
84 views
Why HNO3 acid is stronger than H3PO4?
$\ce{H3PO4}$ can donate 3 protons on the other hand $\ce{HNO3}$ can donate 1 proton. So that makes $\ce{H3PO4}$ stronger isn't it? But my book says $\ce{HNO3}$ is stronger without any explanation.
0
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0answers
19 views
pKa values for amino acid
To calculate the pI value, we take the average of the pKa values from the 2 groups that result in a net charge of 0.
For that to happen, the pKa values should be at the midpoint of titration where ...
3
votes
1answer
198 views
How to make aluminium monostearate?
Can I make aluminium monostearate $(\ce{C18H37AlO4};$ $\pu{344.472 g mol-1})$ by reaction between stearic acid $(\ce{C18H36O2};$ $\pu{284.484 g mol-1})$ and aluminium hydroxide $(\ce{Al(OH)3};$ $\pu{...
-1
votes
1answer
38 views
How to predict whether a salt will act as an acid or as a base in aqueous medium? [closed]
How to would we know if a salt such as $\ce{CO_2}$ reacts acidic or basic in water.
The explanation I see everywhere is that you have to see the acid and base that makes up the salt, in the case of $\...
0
votes
0answers
13 views
Why does the hydride ion in LAH act as a nucleophile rather than a base in the reduction of carbonyl compounds? [duplicate]
Why does the $\ce{H-}$ ion in $\ce{LiAlH4}$ act as a nucleophile rather than a base in the reduction of carbonyl compounds ??
Because $\ce{H-}$ being a small ion would act as a better base than a ...
