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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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How sure can we be about the structure of purine?

While answering the question Basicities of nitrogen atoms in purine, I noticed, that there might be a rapid interchange of the hydrogen bonded to the nitrogen atoms. I have found a crystal structure ...
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Protonating/basic site and Brønsted basicity orders of beta, gamma, and delta lactams

Consider the three cyclic amides: $\beta$-lactam $\gamma$-lactam $\delta$-lactam My question What is the basic site (site of protonation) for these three lactams? And what should be their Brønsted ...
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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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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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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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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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377 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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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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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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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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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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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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No phenolphthalein mono-anion?

This is a follow-up to the question here. There is no mono-anionic stage shown, does it "disproportionate" to the neutral molecule and the di-anion?
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Can Hydronium Act as a Ligand?

Can hydronium function as a ligand? For instance could there exist $\ce{[Al(H3O)4]^{+7}}$ or $\ce{[Fe(H3O)6]^{+9}}$ cations? I asked my chemistry teacher and he said that he's never encountered a ...
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Why does saline have a pH of 5.5?

I am a physician and administer 0.9% NaCl in water ("normal saline") to patients frequently. The bag says it has a pH of 5.5 (compared to the human body of 7.4). I am asking why the pH is so low. It ...
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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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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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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 ...
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Why does the open circuit voltage of a battery decrease with increase in pH of electrolyte, but the voltage across a load increase?

I tested a cell which had aluminum sulfate as its anode electrolyte (12 grams aluminum in 50 mL water and a pH of 3.2), and potassium hydroxide as the cathode electrolyte (5 grams of KOH in 200 g of ...
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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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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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Mechanism for reaction between hydrochloric acid and magnesium

Balanced equation: $$\ce{Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g)}$$ However, Cl- is a spectator ion so the actual reaction equation is: $$\ce{Mg + 2H+ -> Mg^2+ + H2}$$ Here is my proposed ...
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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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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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Electron donating ability of substituted amines on aromatic ring

How would you arrange the conjugate bases of the following amines in order of electron donating ability as EDGs as substituents on an aromatic ring? $\ce{NH3}$, $\ce{(C2H5)(C2H4CN)NH}$, $\ce{(C2H4OH)...
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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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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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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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Help with idea for an optical ph sensor

I am experimenting at home with the idea of making an optical ph sensor that can read the colour of ph indicator using photodiodes. I am wondering if there is some kind of ion permeable membrane ...
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228 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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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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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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Mixing two buffers of the same concentration, but of different pH

Does anyone know how to approach this? I have two buffers of the same weak acid of the same molarity but at different pH Let's say the pH of one was 8 and one was 7, how do I go about getting a pH ...
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Why is the degree of dissociation for a weak acid α, but for a weak base, it's 1−α?

From the equation used in this answer: Calculating charge on amino acid from pKa $$\alpha=\frac{1}{10^{\mathrm pK_\mathrm a-\mathrm{pH}}+1}$$ Degree of dissociation of weak acid is $\alpha$. However,...
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Acid-Base Conjugate Pairs with multiple Products

Identify the acid-base conjugate pairs in the following reactions: $$\ce{H_2SO_4 + HNO_3 <=> HSO_4^- + NO_2^+ + H_2O}$$ The obvious acid base conjugate pair is $\ce{H_2SO4}$ and $\ce{HSO_4^-}$...
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Lassaigne's test for sulfur

The sodium fusion extract is acidified with acetic acid and lead acetate is added to it. A black precipitate of lead sulphide indicates the presence of sulphur. What is the need for acidification of ...
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Application of limiting reagents and acid-base stoichiometry

I'm having a bit of trouble with the latter questions of this problem. $\pu{15.0 mL}$ of $\pu{1.4 M}$ $\ce{HCl}$ was mixed with $\pu{1.00 g}$ of $\ce{CaCO3}$ until all the solid had dissolved. The ...
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Identifying a polyprotic acid using titration

I have the following question from a high school chemistry lab: If an unknown acid has more than one equivalence point, is there a reason to expect a specific $K_\mathrm{a}$ ($K_{\mathrm{a1}}$, $K_{...
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HSO4- ion equilibrium, which side more acidic

I did an experiment in involving the reaction $\ce{HSO4- + H2O -> H3O+ + SO4^{2-}}$. An acid/base indicator was added to the solution. When more $\ce{SO4^{2-}}$ was added to the solution, it ...
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Why would the effect of fluoride ions Protecting egg shells from acid erosion vary with different acids?

I did an experiment reacting egg shells and acid. The egg shells were soaked in varying concentrations of fluoride and it is seen the rate of reaction between egg shells and acid decreases with higher ...
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Relative etch rates of nitric acid on metals and oxides

I am trying to either find or calculate the etch rate of nitric acid ($\ce{HNO3}$) for various different metals and oxides. The ones I am interested in are titanium ($\ce{Ti}$), zirconium ($\ce{Zr}$), ...
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Elimination with Amines

$\hspace{35 mm}$ ATTEMPT: Since $\ce{Et3N}$ is a weak base and the carbon to which $\ce{Br}$ is attached is tertiary, we can rule out $\mathrm{E2}$ and $\mathrm{S_N2}.$ As we are providing heat, the ...
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Why anhydrous acetic acid is differentiating solvent?

Anhydrous acetic acid is differentiating solvent in which strong acids show different strength but water isn't. Why anhydrous acetic acid shows the strength of acids clearly, but water solvent cannot ...
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How are Pauling's rules applied to Nitric acid?

The Lewis structure of nitric acid is: So, since Pauling's rule is $\mathrm{p}K_\mathrm{a}=8-5p$, where $p$ is the number of oxo groups, how is the rule applied in this instance? $p=1.5$? $p=2$?
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How to prevent Tin ions from precipitating as Tin(II,IV) Hydroxides

Alright, so Tin ions in most of it's salts have the propensity to form Tin(II,IV) Hydroxides and then precipitating out of aqueous solutions. What can I throw in the solutions to prevent this? Using ...
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Purity of precipitate in selective precipitation

An aqueous effluent contains $12\ \mathrm{mol\ l^{-1}}$ $\ce{Cd^2+}$ and $10\ \mathrm{mol\ l^{-1}}$ $\ce{Mg^2+}$ as solution of nitrates. Current practice is use $\ce{NaOH}$ to selectively precipitate ...
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Dissolving Time Function for Concrete

So I was just exploring some ideas on my own and am having trouble analytically solving the following: Let $D(n,m,T)$ be the time it takes to dissolve an n x n x n cube of concrete in m molar HcL at ...
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Rationalizing Acidities of Ammonium Ion and Hydronium Ion

Stumbled across this interesting practice problem in my organic textbook. I have a few reasons for why $\ce{H4N+}$ is less acidic than $\ce{H3O+}$. 1) Let’s assess conjugate stability first. ...
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Confusion about prioritizing functional groups in case of poly functional organic compounds

According to Wikipedia, sulfonic acid $(\ce{-SO3H})$ is comparatively stronger than carboxylic acid $(\ce{-COOH})$. Then why is sulfonic acid lower in priority than carboxylic acid (while naming poly ...
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How to Separate Copper Nanowires in an Alumina Membrane

So, in my Chemistry Lab we had an experiment to use Whatman alumina membranes and GaIn eutectic to create Nickel nanowires through electrodeposition. So essentially Nickel wire electrode and alumina ...