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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145 views

Is there a reliable chemical theory that predicts pKa based on structure?

Obviously, there are general stability arguments that can be made to estimate relative pKas, such as evaluating the stability of the conjugate base of an acid, or thinking about how polarized the bond ...
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1answer
668 views

The open circuit voltage of a battery: Does it decrease with increase in pH of electrolyte while the voltage across a load increase?

Why does the open circuit voltage of a battery decrease with increase in $\mathrm{pH}$ of electrolyte, but the voltage across a load increase? I tested a cell which had aluminum sulfate as its anode ...
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489 views

Does phosphoric acid remove stainless steel electropolished layer?

Electropolished stainless steel has a high corrosion resistance due to the oxide film that is created during electropolishing. The film mainly consist of chromium(III) oxide. Phosphoric acid is ...
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47 views

Are there acid/base processes in aqueous solution that are so slow that they are kinetically controlled?

This question came up in figuring out what the fundamental differences are between redox chemistry and acid/base chemistry (if any). In redox chemistry, strong oxidants and strong reductants can co-...
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2answers
81 views

Protons and osmotic potential

In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?
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303 views

pKa of different sites of butanone

From what I can tell, deprotonation of the central hydrogen leads to the more thermodynamically stable product (most substituted double bond. i.e. most stabilization by hyperconjugation). Therefore, ...
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2k views

Why is o-fluorophenol a stronger acid than p-fluorophenol?

The $\mathrm{p}K_\mathrm{a}$ value of o-fluorophenol is $8.7$, while that of the p-fluorophenol is $9.9$. It's obvious that the inductive effect is more dominant at ortho-position, which results in a ...
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396 views

How does a 5th hydrogen bind to carbon atom in CH5[+]?

Can we bind a fifth hydrogen to a carbon atom if carbon is not in excited state? We have a big discussion in class and cannot clearly answer the question. If carbon atom excites an electron from $2\...
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1k views

Yellow precipitate in SnCl2 solution

I have a few small bottles of 0.5M $\ce{SnCl2}$ solution, however solution was prepared about 4 months ago, and there is a yellow precipitate on the bottom of each bottle. Working hypothesis is that ...
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507 views

Ligand strength - Coulombic effect and/or Electronegativities?

According to my teacher, these three Lewis bases generally decrease in strength in the following order: Ammonia Water Hydroxide ion I agree. However, he argues that their ability to act as Lewis ...
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76 views
+50

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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1answer
76 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 ...
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116 views

What pH value of 1M sodium crotonate solution supposed to be?

I need to prepare the $\pu{1M}$ solution of sodium crotonate, however, I don't have one in lab, but I do have sodium hydroxide and crotonic acid. Thus, I calculated that for $\pu{100 mL}$ of $\pu{1M}$ ...
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58 views

What acids, solvents is lithium-6 fluoride soluble in (other than HF)?

$\ce{LiF}$ is quite insoluble in water, and I'm trying to use some water-soluble acid or solvent to dissolve $\ce{^6LiF}$ (95% enriched) in. I'm not a chemistry person, I'm a radiation detection ...
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72 views

Why does my rainwater turn yellow if I increase the pH to 7?

My rainwater is colourless when collected, but if I add a small amount of sodium hydroxide to increase the pH to about 7, after a few days it goes yellow. The colour change happens more quickly if I ...
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1answer
932 views

Which one is the stronger Lewis base: diethyl ether or tetrahydrofuran?

I am trying to understand Lewis bases (bear with me, I am a physicist). I was asking myself how diethyl ether and tetrahydrofuran compare with respect to their properties as solvents in electrophilic ...
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624 views

Which is the stronger base?

I would like to know which of the two is the stronger base, tri-(n-butyl)amine or tri-(tert-butyl)amine? I feel that the one with tert-butyl would be stronger as the inductive effect of tert-butyl ...
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3answers
8k 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{...
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114 views

Is there a way to force C-protonation of an enolate?

In another question, I mentioned that O-protonation of an enolate followed by tautomerization may lead to increased amounts of the thermodynamic product over the kinetic product (when those are ...
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735 views

Is phosphorus trichloride really a stronger Lewis acid than antimony pentafluoride?

The following was a question from the ETS Chem GRE guide and apparently this was an actual question on an exam a few decades ago. Unfortunately, no explanation for the answer was given, and I couldn't ...
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118 views

Is there an adhesive that is not dissolved by acetone?

I am trying to glue glass sheets together to make a sealed 13" x 13" x 13" box. Inside this box there would be acetone gas used to melt 3D printed parts to make them more durable. Acetone will remove ...
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155 views

How can should one separate and purify benzophenone from salicylic acid?

I am working with two solids and I know that they are benzophenone (s)(ketone) and salicylic acid (s) (carboxylic acid). I am curious to know what is/are the best method of extraction and ...
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86 views

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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41 views

acid strength: Periodic trends vs delocalisation, which one is more important

In 1st year chemistry questions, the concept of acid strength is often introduced to students including the 3 factors that provide a heuristic explanation for most of the common acids and conjugate ...
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372 views

Solubility of PbSO4

The solubility of $\ce{PbSO4(s)}$ increase with the addition of $\ce{H2SO4}.$ Why? I don't quite understand this. When dissolving $\ce{PbSO4(s)}$ we get the equilibrium equation: $$\ce{PbSO4(s) <=...
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89 views

Basicity af N containing aromatic species

Hello friends, I got struck in this interesting question on basicity. I am able to get different answers applying different methods. In general, for these compounds we have to see the lone pair ...
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112 views

Naming convention for buffer solutions/systems

Is there an official naming convention to follow for buffer solutions/systems? I've noticed that the name of the buffer usually just follows the name of the salt (ex. sodium acetate buffer), but what ...
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2k views

Can ethylene glycol enhance the acidity of orthoboric acid?

My textbook says: Boric acid is a weak monobasic acid but on addition of certain organic polyhydroxy compounds, such as mannitol, glycerol, dextrose or invert sugar, it is transformed into a ...
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82 views

What metal is used to back this mirror?

My father is attempting to remove the mirror from a piece of glass. We stripped the black paint from the back and exposed the shiny surface with acetone. In the past he has been able to remove ...
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0answers
83 views

Can someone help me finish this reaction?

This question revolves around sodium percarbonate (https://en.m.wikipedia.org/wiki/Sodium_percarbonate) and its reaction with sulfuric acid. I didn't find anything, so I tried assembling it myself. ...
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164 views

Collective term for acid/base; hydronium/hydroxide

When writing about acids and bases it would seem very natural for me to abstract the set of both acids and bases and have a single noun for them, instead of cumbersomly listing them both each time. ...
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1answer
2k views

Titanium in HF vs HCl

So we tried the reaction between Titanium metal with hydrochloric acid and hydrofluoric acid at a similar concentration. While boiling temperatures and constant heat over a long period of time are ...
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1answer
203 views

One half of a nail is exposed to vinegar. Un-exposed half develops a brown film. What is it?

I have recently done an experiment for my chemistry EEI (Year 12) where we are testing what factors effect the rate of corrosion. I used vinegar (acetic acid) as one of the acids and Hydrochloric acid ...
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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 ...
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43 views

Stability of a carbanion that is attached to three phenyl groups

I had come across a question - which asked me to predict the stability of a carbanion attached to 3 phenyl rings, in opposed to one in which the same 3 phenyl rings that are attached to the carbanion ...
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25 views

What are the compounds in oxygen and carbon dioxide indicator solutions that gives their color?

My brother had some leftover oxygen and carbon dioxide indicator solution for one of his take-home experiments from school, so he let me have them. I want to use them for an experiment and write out ...
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213 views

Why is N,N,2,6-tetramethylaniline less basic than N,N,2-trimethylaniline?

According to me, N,N,2,6-tetramethylaniline should be more basic than N,N,2-trimethylaniline due to more steric inhibition to resonance, but the answer is given opposite. What is the reason for that?
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1answer
65 views

Acidity of thiamine - how comes hydroxide anion with pK about 15 ionizes thiamine with pK about 18?

Textbooks say removing proton from thiamine's C atom will produce a resonance stabilized carbanion which is hence bioactive. That's OK, but how comes that 1) we abstract the acidic proton with the OH ...
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28 views

Acidity comparison on R-PO3H2

Question Compare the acidity $(K_\mathrm{a1})$ of the following three acids: $\ce{H3PO4},$ $\ce{Ph-PO(OH)2}$ and $\ce{H3C-PO(OH)2}.$ Thoughts These three acids are of type $\ce{R-PO3H2},$ where ...
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350 views

Basicity comparison between pyridine amines and other compounds

In cases 1, 2, 3, the compounds will resonate, thus giving them more stability. Firstly, I want to know whether nitrogen has a +M effect? (due to it having a lone pair of electrons?) In case 1, ...
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82 views

Common ion effect

Let $\ce{HA}$ ($x$ molar) be a strong electrolyte and $\ce{HB}$ ($c$ molar) — weak electrolyte. As $\ce{HA}$ is strong electrolyte, it dissociates completely: $$ \begin{array}{lcc} \ce{&HA &-&...
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Effect of H-bonding on o-nitrobenzoic acid

My argument here is regarding the acidity of o-nitrobenzoic acid being greater than p,m-nitrobenzoic acid. In o-nitrobenzoic acid, there is an intramolecular hydrogen bond which makes the bond ...
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204 views

Why AlCl3 more acidic than FeBr3?

In compounds with lone pairs or with charge it is easy to predict acidity of compounds but how to describe acidic nature of such ($\ce{FeBr3}$, $\ce{AlCl3}$) transition element compounds ?
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Acidity comparison of charged group 16 hydrides

March's Organic Chemistry (7th ed - page 337 under "Periodic Table Correlations" in chapter "Acids and Bases") states that: $\ce{H3O+ > H3S+ > H3Se+}$ is the acidity order of these charged ...
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669 views

Why does the proton transfer from the oxygen to the nitrogen atom in imine formation not occur through an intramolecular process?

In my book Organic Chemistry by David Klein, 2nd edition, the book shows that the oxygen atom first takes a proton from an acid, then, the conjugate base of the acid takes a proton from the nitrogen ...
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94 views

Is DNA a base inside the cell?

DNA is deoxyribonucleic acid because it has phosphate groups in every one of it's nucleotides. However, in aqueous solutions protons will ionize, leaving phosphates alone as negative groups, i.e., ...
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382 views

Enthalpy change of chromate-dichromate reaction

I am a uni study doing chemistry. I have taken a little bit in highschool before, but not in a while. In a (nonassessed) practical, we have to predict how heating a chromate/dichromate solution: $$\...
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142 views

Constructing a reactivity series, magnesium more reactive than sodium?

I reacted about $0.25 \,\mathrm{g}$ of magnesium, sodium and lithium in $20 \,\mathrm{ml}$ of $2 \,\mathrm{M} \,\ce{HCl}$ at room temperature. This was all done in a $100 \,\mathrm{mL}$ beaker. I ...
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0answers
130 views

Material that acts as a “sponge” for sulfuric acid?

I would like help with a materials problem I am looking into that pertains to a product I would like to develop. What I seek is some kind of substrate that acts like blotter paper does. Ideally, the ...
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0answers
49 views

Trouble understanding Bradford Assay

From what I understand, the Bradford reagent contains Coomassie Brilliant Blue in an acidic solution so both of the (sulfonic acid groups? I'm not sure if this is the correct name- I can't seem to ...

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