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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Precipitating matals from aqua regia solution [closed]

good day , I have a problem precipitating metals from aqua regia solution that I have made from an ore , it does changes the color when I dip some stannus chloride in to the beaker . But does not give ...
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How do I solve this protolysis-reaction question? [closed]

I have measured $\mathrm{pH}$-values to these solutions and filled in a table: $\ce{NaCl}:9.5-10$, $\ce{CH3COONa}:8$, $\ce{Na2CO3}:11.5$, $\ce{NaHCO3}:2$, $\ce{KNO3}:3$, $\ce{NH4Cl}:7-8$ The question ...
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Why is the solution of ammonium bifluoride more acidic than aqueous ammonium fluoride?

At low concentrations of aqueous $\ce{NH4HF2}$ $(w = 1–2\,\%)$ $\mathrm{pH}\approx 3.$ But aqueous $\ce{NH4F}$ $(w = 20–40\,\%)$ has $\mathrm{pH}\approx 7.$ Yet the equilibria of $$ \begin{align} \ce{...
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Keto Enol tautomerism [duplicate]

I don't understand why the keto form is present more at equilibrium. Yes I know that for phenols or instances where the enol form can have H-bonding the enol form is preferred, but generally I have ...
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1answer
42 views

Dissociation equilibria of ammonium bifluoride in water

Ammonium bifluoride or ammonium hydrogen fluoride is a salt of a weak base and a weak acid. The weak acid is because the second equilibria of $\ce{HF}$ written as: $$\ce{HF + F- <=> HF2-}$$ and ...
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1answer
35 views

Why is carbon dioxide a Lewis acid? [duplicate]

I know this has been asked before, but can anyone explain me in simpler terms? Why is $\ce{CO2}$ a Lewis acid? The carbon atom doesn't have any vacant orbitals to accept a lone pair. How can it be a ...
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1answer
32 views

Why is para-aminobenzoic acid more acidic than ortho-aminobenzoic acid?

Compare the acidic strength of o-, m-, p-aminobenzoic acids. I got that meta will be the most acidic as it won't be able to show R+ effect of $\ce{NH2}.$ But among the other two, i.e. ortho and para, ...
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Concentration of organic acids in lichens/rock substrates/soil (particularly oxalic and citric acid)

I am trying to design an experiment testing the efficacy of lichen acids to solubilize and mobilize nutrients from minerals in a lunar regolith simulant. My research so far indicates that oxalic acid ...
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Why does an alkaline salt and acid not make hydrogen gas

Why does an alkaline salt and acid in solution form CO2 and water? Rather than hydrogen gas and an unchanged negative ion? Doesn’t happen, but is easy to work out without knowing anything empirically: ...
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Why are conjugate pairs needed to make a buffer solution?

Why are conjugate pairs needed to make a buffer solution? Shouldn't the mixture of an aqueous weak acid and the conjugate base of another weak acid still make a buffer solution because the conjugate ...
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593 views

How was pH measured back in the day if you had nothing to calibrate to?

We learn about indicators but these seem awfully useless if you have no clue what pH the color change occurs at. How did early chemists figure this out? I guess more broadly, how was the hydronium ...
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Does 99.8% acetic acid cause severe skin burns like formic acid?

I've so far handled only concentrated fuming nitric, sulfuric & hydrochloric acids from the inorganic side. Even during an accidental spill on the hand I did say only the $\ce{HNO3}$ affects the ...
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50 views

Writing a chemical equation with a reactant of unspecified chain length [closed]

Would appreciate it if I got some general tips and hints and not the solution cause I'm trying to learn from this question :) The question is as follows: FA1 is a solution containing $\pu{5.00 g dm-3}...
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Acid neutralizing capacity of acidic fruits

How do acidic fruits help with acid-reflux? Shouldn't it have a basic pH to neutralize acid? How come certain acidic fruits like citrus help with acid-reflux despite having an acidic pH?
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Ionic product value and pH/pOH

when studying basic acid and base reactions I got some conceptual question. When calculating the pH or the pOH of water we use the following formula: $$\mathrm {pH}+\mathrm{pOH}=14$$ This comes from ...
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Why in weak acids is it easier to take off the H+ ion? [closed]

For example, let's think about HCN (hydrogen cyanide). My instructor says that in Bronsted-Lowry acid/base theory, the weaker the acid easier it is to take off the proton from HCN and make it H+ and ...
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Are all amphoteric substances weak acids and weak bases?

I saw as an example that water is amphoteric (to be more precise amphiprotic), and I came up with the following questions: Is there any substance that acts as a weak acid and a strong bases at the ...
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Remove sulphuric acid from vegetable oil

I have a venture I am contemplating. However I have a problem. I plan to recycle used vegetable oil in animal feed. But, the oil will have some sulphuric acid in it from a prior cleaning process. How ...
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Why do we omit OH- ions from H2O and acid equations

And the converse for bases why do we omit $\ce{H3O+}$ ions? Is it correct to think that when an acid is added to water it shifts the equilibrium to the right for the dissociation of water? ...
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Why does the pKa - pKb relationship hold when Kw holds for the autoionization of water?

The relationship is commonly expressed as: $$pK_a + pK_b = pK_w = 14$$ or $$K_a * K_b = 10^{-14}$$ This holds because $$K_a = \frac{[H^+][A^-]}{[HA]}$$ $$K_b = \frac{[OH^-][HA]}{[A^-]}$$ $$K_aK_b = \...
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Why isn't calcium carbide more corrosive?

Acetylene has a pKa of 26, I think. While that's pretty acidic ... for a hydrocarbon ... I still expect calcium acetylide (carbide) to be a very strong base indeed. Yet the NFPA fire diamond health ...
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What reaction is used for calculating pH of the solution obtained after ethanol oxidation with potassium permanganate?

If $\pu{30.0 ml}$ of $\pu{0.20 M}$ ethanol solution reacts with $\pu{1.80 g}$ potassium permanganate, what will be the final $\mathrm{pH}$ of the solution? Assume a complete reaction and that only the ...
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Neutralisation reaction of HCl (aq) + NaOH (aq): How NaCl forms?

Consider the neutralisation reaction $$\ce{HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)}.$$ I am struggling to understand what happens to $\ce{Cl}$ in this reaction, and how it joins with $\ce{Na}$. $\...
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Cleavage of a peptide bond by a base

Adding concentrated strong base to a solution containing an enzyme often reduces enzyme activity to zero. In addition to causing protein denaturation, which of the following is another plausible ...
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Comparing the acidity levels of different types of tea

I am a high school student and have the opportunity to create a project on a topic that I want. I am thinking of making one on how the acidity of tea is affected by the type and addition of milk and ...
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Do Lewis acids and bases turn change colour of litmus

Well, the question is short. Can lewis acids and bases change the colour of a litmus paper? I can't seem to find the answer online (at least according to my high school level chemistry search history)....
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Why do we need weak or strong acids to displace the anions of other weak acids from salts?

I have already looked at Why does a strong acid displace salt of weak acid? but I couldn't understand the answer and the analogy there. And I mean the above question in the following context : $\ce{...
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How to mitigate salicylic acid saponification?

I started to make soap a few months ago and came up with a few formulas, one of it contains salicylic acid as a exfoliant/anti-acne agent, I've just realized that since salicylic acid is, well, an ...
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62 views

Reaction with sulfuric acid

Which of the following will react with dilute sulfuric acid? : copper, copper (II) oxide, copper (II) hydroxide, copper (II) carbonate. My answer: Metals react with acids to give salt and hydrogen. So,...
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Enthalpy of Neutralisation for HF and strong base

Now I know that when a strong acid and strong base neutralise each other, enthalpy change is almost constant and equal to -57.3 kJ/mol. (This is because no heat is required to ionise the acid and base ...
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Why does acid hydrolysis of glucose-1,6-bisphosphate produce glucose-6-phosphate and not glucose-1-phosphate?

A paper I found details treating glucose-1,6-bisphosphate with 6M HCl to produce glucose-6-phosphate. I'm curious why glucose-1-phosphate (and then even plain glucose) isn't formed instead?
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How do you determine the NIE equation of a buffer? [closed]

For example, I have formic acid and sodium formate. How do I know the NIE(net ionic equation) equation is $\ce{HCHO_2 + H_2O <=> H_3O+ + CHO_2-}$ and not $\ce{HCHO_2 + OH- <=> H_2O + CHO_2-...
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Aspirin Hydrolysis at pH 2

Conducting an experiment, I found that very little salicylic acid was evolved performing hydrolysis at pH 2 and at 45 degrees C. In fact, far more salicylic acid was evolved at pH 7. This comes as a ...
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How do I tell the difference between an acid, base, and a salt solution? [closed]

I'm learning about acid-base equilibria. I know that an (Bronsted-Lowry) acid donates a hydrogen proton, and a base donates a hydrogen proton, but I've also heard about a Lewis acid base theory, where ...
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2answers
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Is this stoichiometric question answerable? (unknown variable)

This question kind of borders on the fields of both semantics and math, as well as chemistry, but I still believe this is the right place to ask. On a test I took, a question was posed as such: Via ...
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How is NaOH a base? [closed]

Firstly, how is $NaOH$ created? My teacher said that before it is $NaOH$, it is $NaO^-$. $$NaO^- + H_2O = NaOH + OH^-$$ If so, that means that $NaO^-$ is a base, which would make $NaOH$ it's conjugate ...
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Would temperature change affect buffer solutions?

Since buffer solutions are composed of an acid + conjugate base (or base + conjugate acid), would any aspects of it be affected by a temperature change? Since acids and bases exist in an equilibrium ...
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Why is the side chain of lysine more basic?

According to the images below, the NH3+ on the side chain of lysine is less acidic than the NH3+ closer to the COO-. Why is this? Wouldn't the NH3+ have an intramolecular H-bond with a negatively ...
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How can I wet etch Nickel Chloride (NiCl/NiCl2) off a GaN sample

Apologies in advance for what may be a basic chemistry question - I'm asking from the point of view of microlithography. I have a Gallium Nitride sample which I have etched in a Ar/Cl plasma with a ...
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Why doesn't base/acid reacting with water create a salt?

An acid/base nwutralization will create a salt + water. If one uses water itself as the acid or base, and have an acid/base neutralization, how come that doesn't create a salt? For example:$$ \ce{HCN(...
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Are all ions bases/acids or their conjugate forms?

If one has a cation, is that always an acid or a conjugate acid? If one has an anion, is that always a base or conjugate base? If not, can you mention any of these ions? Also, if not every ion needs ...
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Why is H2O a weaker acid than acetylacetone? Shouldn't a hydrogen connected to an oxygen be more acidic than a hydrogen connected to a carbon atom? [closed]

I recently started studying chemistry after a long pause in my education so pardon me if it is a simple question. In the organic chemistry course I am taking, the professor told us that the first ...
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1answer
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Why did my vinegar not create the traditional volcano?

At the weekend, my son and I tried the volcano experiment. You know the one: vinegar introduced to sodium bicarb (and a little red dye) within a conical "volcano". Not actually ours; photo ...
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Base/acid reaction -> alcohol amphoteric? why no pkb value?

I have a question concerning acid/base reactions. Is it true that an alcohol is a better base than water? My Professor listed the basicity (because we talked about E1/E2 and Sn1/Sn2 reactions) of the ...
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1answer
58 views

What concentration is phenolphthalein indicator ? 1% or 0.1%

I read some information about phenolphthalein indicator, some websites suggested phenolphthalein indicator of 1%, others mentioned phenolphthalein indicator of 0.1%. What is the difference of both of ...
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1answer
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Why does the pH of a weak acid not increase by 1 when diluted by a factor of 10? [closed]

Strong acid pH increases by one unit when diluted by a factor of 10, but why do weak acids not?
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Identifying which lone pair is more basic?

In the the compound RCONH2 which lone pair is more basic? Is it the lone pairs on Oxygen atom or the lone pair on Nitrogen atom. I believe that as O is more electronegative than N, the lone pair on O ...
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25 views

Acid-Base Titration of ammonium dihydrogenphosphate?

How can I determine the concentration of ammonium dihydrogenphosphate solution? In this compound, the ammonium cation and the dihydrogen anion are both weak acids. I have a weak solution of this salt, ...
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Preparation of ammonium acetate buffer for HPLC

Buffer solutions are typically prepared by dissolving an appropriate salt in water and then adjusting the $\mathrm{pH}$ to the desired position by addition of the conjugate acid or base. For example, ...
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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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