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).
3,147
questions
122
votes
7
answers
82k
views
Is a negative pH level physically possible?
A friend of mine was looking over the definition of pH and was wondering if it is possible to have a negative pH. From the equation below, it certainly seems mathematically possible—if you have a $1.1$...
- 1,339
100
votes
7
answers
323k
views
Is it actually possible to dispose of a body with hydrofluoric acid?
In the TV show "Breaking Bad", Walter White frequently gets rid of people who get in his way by submerging them in a plastic container full of hydrofluoric acid. This, at least in the TV show, ...
user1579
78
votes
7
answers
52k
views
Ortho-effect in substituted aromatic acids and bases
When comparing o,m,p-toluidine basicities, the ortho effect is believed to explain why o-toluidine is weaker. But when comparing o,m,p-toluic acid basicities, the ortho effect is stated as a reason ...
- 939
60
votes
4
answers
242k
views
Why add water first then acid?
From school, I remember a very important rule: first you need to pour the water and then the acid (when you need to mix them) not vice-versa. This is because otherwise the aсid becomes very hot and ...
- 1,043
54
votes
2
answers
21k
views
Why don't we explode after drinking water?
It is known that acid should be added to water and not the opposite because it results in an exothermic reaction.
Our stomach contains HCl, so why don't we explode when we drink water?
- 737
45
votes
4
answers
52k
views
The reason behind the steep rise in pH in the acid base titration curve
Most books refer to a steep rise in pH when a titration reaches the equivalence point. However, I do not understand why … I mean I am adding the same drops of acid to the alkali but just as I near the ...
- 2,405
44
votes
2
answers
20k
views
Why does CaCO3 react with HCl, but not with H2SO4?
I have a wonderful reaction of marble chips, $\ce{CaCO3}$, with hydrochloric acid, $\ce{HCl}$, and carbon dioxide was released beautifully (fast, large volume, easy to measure and makes good visual ...
- 960
44
votes
4
answers
9k
views
What is more acidic: D3O+ in D2O or H3O+ in H2O and why?
What is more acidic:
$\ce{D3O+}$ in $\ce{D2O}$
or
$\ce{H3O+}$ in $\ce{H2O}$
and why?
I think it's $\ce{D3O+}$ in $\ce{D2O}$ as I saw somewhere that this property is used in mechanistic studies (...
- 14.2k
41
votes
2
answers
9k
views
Why is arsenous acid denoted H3AsO3?
Inspired by this question, I'm wondering why arsenous acid is frequently denoted $\ce{H3AsO3}$, as opposed to $\ce{As(OH)3}$, which would appear to more accurately reflect its connectivity?
[edit]
I ...
- 10.8k
41
votes
3
answers
32k
views
Is methanol more acidic than water?
Methanol is slightly more acidic than water. Their $\mathrm{p}K_\mathrm{a}$ values, in water, are $15.5$ and $15.7$, respectively. All other aliphatic alcohols, however, are less acidic than water.
...
- 18.6k
39
votes
2
answers
20k
views
Why is pyrimidine less basic than pyridine?
From Wikipedia's article on pyrimidine:
Because of the decreased basicity compared to pyridine, electrophilic substitution of pyrimidine is less facile.
But why is pyrimidine less basic than ...
- 3,246
35
votes
9
answers
12k
views
Would it be possible to destroy gold?
I'm a writer. I have a scenario in which a sizable amount of gold needs to be rendered unusable, preferably completely destroyed. I know an acid like aqua regia is able to dissolve gold, but would ...
35
votes
1
answer
58k
views
Acidity of substituted phenols
Phenol has a $\mathrm pK_\mathrm a$ approximately equal to $9.9$.
When one studies the acidity of chlorophenols, one notices the following:
First of all, chlorophenols are more acidic than phenol, ...
- 1,738
34
votes
4
answers
66k
views
What's the difference between a nucleophile and a base?
Obviously it depends on the context whether you would call a particular species a nucleophile or a base but are the two terms largely synonymous or is there a difference?
- 9,736
32
votes
2
answers
34k
views
What is the pKa of the hydronium, or oxonium, ion (H3O+)?
Although the wikipedia page on Hydronium indicates a $\mathrm{p}K_\text{a}$ of −1.74, I noticed in the discussion of this page that the subject seems debated (cf. http://en.wikipedia.org/wiki/Talk:...
- 587
31
votes
3
answers
25k
views
What is the strongest acid?
According to Wikipedia, $\ce{HeH+}$ and fluoroantimonic acid are the strongest.
According to a News article in Nature, Carborane acid is the strongest, but Wikipedia says fluoroantimonic acid is ...
- 1,653
30
votes
1
answer
12k
views
Why does lemon juice reduce the "fish" odor of sea food — specifically fish?
In studying amines, I read that lemon juice is also used to wash fish because it reacts with the amines on and in the fish to convert the amines to its salt, just reducing the "fishy smell".
...
- 427
28
votes
5
answers
62k
views
Acid Accident Treatment
What are the general ways to treat an accident involving highly concentrated or similarly dangerous acids?
I have a lab instructor who recently debated with our group about treating an acid spill on ...
- 2,537
28
votes
2
answers
5k
views
How to properly store acids at home?
I bought different kinds of acid for experiments and home usage that I stored in secured containers into an IKEA cabinet.
I just realized that despite the fact that all the containers are properly ...
- 603
28
votes
3
answers
10k
views
Which molecule is more acidic: CHF3 or CHBr3?
I know that fluorine is more electronegative than bromine. However, because of the size of bromine, it is more stable with a negative charge. In the case of $\ce{HF}$ vs. $\ce{HBr}$, to me, $\ce{HBr}$ ...
- 281
26
votes
4
answers
43k
views
Why is acetic acid more acidic than phenol?
Acetic acid (ethanoic acid, $\mathrm pK_\mathrm a \approx 5$) is more acidic than phenol ($\mathrm pK_\mathrm a \approx 10$), which is reflected in their reactivity with a weak base such as sodium ...
- 621
26
votes
4
answers
3k
views
What software can calculate aqueous solution equilibria?
What software is available out there to calculate the equilibrium in a set of reactions in aqueous solution? In particular, I'm interested in software general enough to simulate things like titration ...
- 23.6k
25
votes
3
answers
194k
views
How does one tell if a specific molecule is acidic or basic?
Let's take the $\ce{KOH}$ molecule into account. I know it is a base from literature, but how would one go about determining if a molecule is acidic or basic simply based on the structure of the ...
- 795
25
votes
4
answers
6k
views
Does nitrogen inversion affect the basicity of amines?
If I were to compare the basic strength of 1-azabicyclo[2.2.1]heptane and triethylamine:
Can I say that 1-azabicyclo[2.2.1]heptane is more basic than triethylamine because the lone pair of electrons ...
- 7,676
25
votes
3
answers
12k
views
The acidity of boric acid
The “real way” boric acid behaves as an acid in water is first by acting as a Lewis acid (bottom reaction, in black). In fairness to the undergrads, I’d bet >25% of graduate students around the ...
- 18.6k
24
votes
5
answers
29k
views
Is there such a thing as an acid without a hydrogen?
I'm in AP Chemistry and we are learning about the Brønsted-Lowry model and my teacher mentioned that "for the most part" acids have hydrogen, could there be such a thing as an acid that has no ...
- 435
24
votes
2
answers
10k
views
Comparing acidities of substituted and aromatic carboxylic acids
When comparing the acidities of carboxylic acids, we primarily see the electropositivity of the carboxylic acid carbons, i.e. we see how effectively the negative charge on the carboxylate ion is ...
- 6,727
24
votes
2
answers
7k
views
Is HF the least acidic hydrogen halide?
Fluorine is the most electronegative halogen and therefore, there is larger difference in electronegativity between the atoms of $\ce{HF}$ than any other hydrogen halide, which means the positive ...
- 1,483
24
votes
2
answers
30k
views
Why are the majority of cleaning solutions basic?
When testing for pH for common household cleaning products, such as dishwasher fluid, I noticed that majority of them tend to be basic? Why is that? Do acid make good cleaning solutions as well?
- 341
24
votes
1
answer
46k
views
How does adding lemon juice to sugar make better caramel?
It's a common cooking advice: if you want a somewhat softer caramel, add some lemon juice to the sugar:
To help prevent the caramel from crystallizing, you can add an acid to the sugar before you ...
- 23.6k
23
votes
3
answers
3k
views
Is "Sulfuric acid... makes a poor electrolyte... very little of it will dissociate into ions" really true? What does that actually mean?
While researching chromate conversion coating for edits to this answer in Space Exploration SE, I came upon the following passage in Corrosion Resistance of Stainless Steel to Sulfuric Acid
Sulfuric ...
- 5,742
23
votes
4
answers
67k
views
Reason for the stronger acidic property of phenol than alcohol
In phenol, pulling the $\mathrm{p}_z$ electrons from the oxygen atom into the ring causes the hydrogen atom to be more partially positive than it is in aliphatic alcohols. This means it is much more ...
- 2,405
23
votes
2
answers
12k
views
Side reactions of N-hydroxysuccinimide esters with nucleophiles
N-Hydroxysuccinimide (NHS) chemistry is commonly used in chemical biology to react with primary amines like lysine and the N-terminus of proteins. I was curious how labile NHS esters are to other ...
- 2,380
22
votes
4
answers
13k
views
What's the strongest known organic acid?
What's the strongest known organic acid? Is it maybe trifluoromethanesulfonic acid or tautomer of pentacyanocyclopentadiene?
EDIT: Since the question was reactivated I thought about formalising it. I ...
- 4,575
22
votes
4
answers
8k
views
Why do Organolithium or Grignard reagents act as nucleophiles and not as bases with aldehydes and ketones
I've read entire Chapter 14: Organometallic Compounds of Francis Carey's "Organic Chemistry" but I still didn't get an answer to my question.
Quote from the book:
Because of their basicity ...
- 955
22
votes
1
answer
6k
views
Could milk rust a steel teaspoon?
Recently, while cleaning a neighbour's fridge (turned off for a few weeks), I came across a cup (closed with a lid). Inside the cup was, to my olfactory horror, congealed milk, with a steel (iron) ...
user15489
22
votes
3
answers
3k
views
How was it concluded that the H3O+ rather than H+ is the "acid" ion?
I suspect that initially, scientists believed that the acid ion was $\ce{H^+}$ since $\ce{H2}$ is released through electrolysis, right? But what experiment was done to change the standpoint to assume ...
- 369
22
votes
1
answer
4k
views
How can I safely handle a concentrated (fuming) nitric acid spill?
I will shortly be using $90~\%$ or higher concentration nitric acid in a home environment for the purpose of decapping ICs. I understand the corrosive dangers of nitric acid, and most of the important ...
- 331
22
votes
4
answers
85k
views
Why is salt needed when using vinegar to clean pennies?
Let's say you have a solution that is vinegar and it has salt (NaCl) dissolved in it. Then you place old dull pennies in it. Then you look at it 5 minutes later and the pennies are clean and looking ...
- 229
21
votes
2
answers
21k
views
Why formulate drugs as HCl salts when HCl is in stomach acid?
I know there are issues of formulation and industrial processing that make it advantageous to produce many amine containing drugs as their salts rather than as freebases. And if giving the drug ...
- 219
21
votes
3
answers
16k
views
Does the number of H+ ions in solution go up on dilution of a weak acid?
In my textbook, a footnote says:
In case of weak acids, on dilution the total number of $\ce{H^{+}}$ ions in solution increases because dissociation of the weak acid increases
This didn't make ...
- 3,433
21
votes
2
answers
7k
views
Chemical compounds responsible for the colors in flowers?
I know that anthocyanins are a class of compounds responsible for the purple colors found in flower petals.
Anthocyanins (also anthocyans; from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = ...
- 6,106
21
votes
4
answers
37k
views
Acidity order of nitrophenols
As in other posts I have seen and learnt that, if one is given four compounds, namely para-nitrophenol, ortho-nitrophenol, meta-nitrophenol and phenol and is told to arrange them in order of acidity, ...
- 800
20
votes
3
answers
7k
views
Why is magic acid a superacid?
The above is a representation of magic acid. The left part is the acid; the right part is the solvent. Why would this combination make for a particularly good acid?
The left part looks like a ...
- 18.6k
20
votes
3
answers
10k
views
Why is ammonium a weak acid if ammonia is a weak base?
$\ce{NH3}$ is a weak base so I would have expected $\ce{NH4+}$ to be a strong acid. I can't find a good explanation anywhere and am very confused. Since only a small proportion of $\ce{NH3}$ molecules ...
20
votes
2
answers
9k
views
What are the crystals that have formed around the top of a conc. nitric acid bottle?
I was looking through my chemicals cupboard and found that this decades-old bottle of conc nitric acid had grown a beard. I can't think of any reaction between (presumably) $\ce{NO2}$ and any airborne ...
- 209
20
votes
4
answers
60k
views
Why is formic acid a stronger acid than acetic acid?
I am told that because the methyl group is electron donating in the conjugate base of acetic acid, this destabilizes the conjugate base by exacerbating the existing negative formal charge on the ...
- 18.6k
20
votes
4
answers
2k
views
Is the proton the strongest acid?
Having looked at the various definitions of acids and bases and having refined my understanding of it after learning about the inadequacies of pKa and the novel use of the Hammett acidity function, I ...
- 10.2k
20
votes
1
answer
19k
views
Relative acidities of alkanes, alkenes, and alkynes
How does one explain the trend in bond lengths and acidity of the following hydrocarbons?
$$\begin{array}{ccc}
\hline
\text{Species} & \ce{C-H}\text{ bond length / Å} & \mathrm{p}K_\mathrm{a} ...
- 2,537
20
votes
1
answer
3k
views
Why is proton transfer so fast?
Why is proton transfer always kinetically favored? In other words, why are Brønsted acid-base reactions so quick?
Is it because protons are generally unhindered, sterically? This seems plausible; ...
- 18.6k