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).

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2
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0answers
47 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.
-3
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0answers
11 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 ...
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0answers
18 views

Why at lower pH than pKa, acid doesn't dissociate to give H+ ions [on hold]

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?
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1answer
68 views

Does hyperconjugation into sigma-star explain methylamine's increased basicity relative to ammonia?

The inductive effect with the polarisation of the C-N bond obviously plays a role in stabilising the positive charge of the conjugate acid. But given the similar electronegativities for C and H, CH3 ...
3
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1answer
102 views

Rechargeable Battery Based on Neutralization Reaction of Acid and Base [on hold]

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 ...
0
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0answers
29 views

What is the logic behind a 28% ammonia solution being labeled as 56.6% in ammonium hydroxide? [on hold]

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
2k views

How to calculate pH of the Na2CO3 solution given ambiguous Ka values

This is the exact question I faced on an exam. Calculate the pH of $\pu{0.05 M}\ \ce{Na2CO3}\ (\ce{H2CO3}: K_\mathrm{a,1}= 4\times 10^{-7},\ K_\mathrm{a,2}= 4.7\times 10^{-11})$ Solution $$\ce{...
-2
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1answer
59 views

Why does the addition of tetraethyl ammonium bromide reduce solution pH? [closed]

I am looking at a system that adds tetraethyl ammonium bromide to water. Over time, the concentration of tetraethyl ammonium bromide gradually increases, leading to a fall in the pH. I am trying to ...
0
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1answer
30 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 $\ce{CF3}$, ...
6
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5answers
154k views

How to calculate the concentration H3O+ in a solution with pH=6.99?

What is the correct way to calculate the concentration $\ce{H3O+}$ in a solution with $\ce{pH}=6.99$? Attempt 1. pH<7, therefore there are only $\ce{H3O+}$ particles in the solution. $[\ce{H3O+...
98
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8answers
55k views

Is a negative pH level physically possible?

A friend of mine was looking over the definition of pH, and wondering if it is possible to have a negative pH level. From the equation below, it certainly seems possible—just have a $1.1$ (or ...
1
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1answer
49 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{...
5
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1answer
2k views

Comparing Acidic Strength of H3PO4 and H3AsO4

The $pKa$ values for H3AsO4 and H3PO4 are $2.30$ and $2.12$ which indicate that H3PO4 is a stronger acid compared to H3AsO4. I looked up their electronegativity values to find that they are almost the ...
9
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2answers
788 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 ...
-1
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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 ...
-1
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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 ...
1
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1answer
65 views

Boiling chips for concentrating sulfuric acid

I am concentrating sulphuric acid. What should I use as boiling chips? I have tried broken mug pieces, the solution became cloudy, and I have tried broken glass (retrieved from a drinking class, not ...
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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? [on hold]

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
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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 ...
4
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1answer
190 views

Using acidic detergents

If detergents were acidic rather than basic, can we still achieve a clean surface? What would be more effective? Strong acid or a weak acid? How would the result of cleaning be different if an acid ...
0
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1answer
57 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 ...
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1answer
264 views

Can organic acids be concentrated and used like concentrated sulfuric acid and similar mineral acids?

Is it possible to make organic acids concentrated like inorganic acids like concentrated sulfuric acid and similar mineral acids?
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0answers
30 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 ...
6
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1answer
195 views

How to derive the conductivity titration curve which accounts for salt formation

I derived an equation that gave me the volume of base required to get a certain $\mathrm{pH}$: In a titration between a weak acid $\ce{HA}$ and weak base $\ce{B}$ (adding base into acid solution) the ...
5
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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 ...
6
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2answers
814 views

Steric inhibition of resonance vs. hydrogen bonding

I have to compare the acidic strength of these compounds: Now, in A and B hydrogen bonding will be present which will help stabilize the negative charge of the conjugate base. However, the hydroxyl ...
0
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1answer
34 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 ...
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0answers
27 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 ...
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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: ...
16
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1answer
622 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 ...
0
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1answer
626 views

Acidic strength of organic acids. Substituted PhCOOH acids

Could someone please explain the order of acidity of ortho, para and meta substituted benzoic acids with the substituent as methyl group? Methyl group operates +I and +R effect, I believe.
0
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1answer
64 views

pH of an acetate buffer after dilution

100 mL of a 0.1 mM buffer solution made from acetic acid and sodium acetate with pH 5.0 is diluted to 1 L. What is the pH of the diluted solution? The pKa value for acetic acid is given as 4.75. The ...
0
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1answer
160 views

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�...
2
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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) ...
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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?
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 ...
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3answers
107 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: $\ce{NH3 + H2O -> NH4OH}$ ...
8
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1answer
299 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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1answer
61 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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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
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3answers
4k views

Order of Basicity of Nitrogen Trihalides

I was asked to arrange nitrogen tri-halides in order of increasing basicity. On looking up the answer online, it turned out to be the following: $\ce{NF3}$ < $\ce{NCl3}$ < $\ce{NBr3}$ < $\ce{...
8
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2answers
54 views

Will using vinegar harm car paint?

After having parked my car in a newly constructed airport parking garage, I came back to find something had dripped through a crack in the ceiling of the structure and left considerably thick film on ...
0
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2answers
335 views

Why ammonium hydroxide precipitates metal salts?

When I was going through the chapter on pnicotgens, I got to know that ammonia acts as a Lewis base and it dissociates in water giving out hydroxide ion and the further hydroxide of ammonia, which we ...
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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 ...
2
votes
1answer
114 views

Aromaticity fails?

Why is cyclopentadiene ($\mathrm{p}K_\mathrm{a} = 16$) less acidic than A) 2,4-pentanedione $(\mathrm{p}K_\mathrm{a} = 9);$ B) phenol $(\mathrm{p}K_\mathrm{a} = 10);$ C) water $(\mathrm{p}K_\mathrm{a}...
0
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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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1answer
81 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.
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0answers
44 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
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1answer
106 views

Understanding the increase in pH of a buffer solution upon incremental additions of NaOH analytically

So let's say we have $200\ \mathrm{mL}$ of $1\ \mathrm M$ $\ce{CH3COOH}$ solution. In this solution we have the equilibrium $\ce{CH3COOH <=> CH3COO- + H+}$. To that we add $100\ \mathrm{mL}$ of $...