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 to determine the equivalent weight of CO2

We were estimating dissolved $\ce{CO2}$ in water by American Public Health Association method. It was a titrimetric method using phenolpthalein indicator. Titrant used was $\ce{NaOH}$ and analyte was ...
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1answer
822 views

Acidity of ester and benzoic acid

Can the oxygen in an ester participate in resonance donation? I think so, although the donation is slight. The hybridization is correct. However, resonance withdrawal by the ring via the oxygen doesn'...
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Lewis base strength and the hydrogen proton

My prof told me that we can compare Lewis base strength based on electron donation to the $\ce{H+}$ proton - i.e sigma bond formation with the $\ce{H+}$ proton - and proceeded to conclude that $\ce{S^{...
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Calculating approximate pH of polyprotic acids

When I took up ionic equilibria and titrations after a long break, I found it hard to solve the questions regarding pH calculations of polyprotic acds. Consider these two questions as examples:- ...
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2answers
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t-butylbenzene in highly acidic medium

Why would the following mechanism be valid for the conversion of t-butylbenzene to benzene in highly acidic medium followed by an aqueous workup? The main problem I have with this mechanism is the ...
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1answer
7k views

Is acetate a weak base due to its resonance structure?

I just read that acetic acid is an exception to the general idea that the conjugate base to a weak acid is a strong base. The example says that the conjugate base of a weak acid will only be strong ...
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2answers
4k views

What is double titration?

I an currently studying acid-base titrations. There is a concept of double titration. Can someone provide me an idea on what actually it is? Also what resources can I refer to?
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1answer
18k views

Calculating pH: Weak Acid, Strong Base

This is a question that had me puzzled for quite a while. I feel that information is missing. A weak acid, $\ce{HA}$, $K_a = 1.0$ x $10^{-4}$, is titrated with $\ce{NaOH}$. At the equivalence point,...
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2answers
36k views

Finding new pH after NaOH added to buffer solution

I have a buffer containing 0.2 M of the acid $\ce{HA}$, and 0.15 M of its conjugate base $\ce{A-}$, with a pH of 3.35. I need to find the pH after 0.0015 mol of $\ce{NaOH}$ is added to 0.5 L of the ...
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1answer
199 views

Why degree of dissociation/ionisation affected by dilution? [closed]

What happens when we dilute, say, an acid which is weak, and then add water to it? What motivates or pushes it to dissociate more? We are just adding some molecules of water, right? So, what exactly ...
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0answers
827 views

Decarboxylation mechanism and stability of α,β-unsaturated and α-hydroxy acids

I was wondering why α,β-unsaturated and α-hydroxy acids undergo decarboxylation. Also, I'm aware of neither the products nor mechanism. All I know is that β-keto acids and α-nitro compounds have ...
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1answer
1k views

In which direction does imidazole affect the pH?

I'm reading something about nickel affinity chromatography and it talks about using imidazole to affect pH. In which direction does it change the pH?
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1answer
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How do I store HCl safely?

I'm in a textile unit, where we use different chemicals. My question is what type of material should I make my tank out of to store my hydrochloric acid?
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2answers
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Why is sodium sulfate a neutral salt [duplicate]

When I have a solution of $\ce{Na2SO4}$, the sodium sulfate should ionize: $$\ce{Na2SO4(aq) -> 2Na+(aq) + SO4^{2-}(aq)}$$ In my mind, the sodium ions should just float around, but because $\ce{...
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1answer
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Comparing Basic strengths of different species

I was doing questions on organic chemistry. I came across tonnes of questions where I was required to compare basic and acidic strengths. Comparing acidic strengths is fine — I remove an $\ce{...
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1answer
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Soap versus Shampoo

Soap and shampoo are both cleaning agents in our daily life. Why is soap in solid form and shampoo is in a liquid form, though? Is it because of the chemical components inside them or another factor?...
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796 views

why are amines more water soluble than alcohol for similiar molecular weight?

kindly someone please explain the reason behind this behaviour despite the fact that oxygen is more electronegative and forms stronger hydrogen bond.
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725 views

Why is the water dissociation constant valid for acid/base solutions?

The water dissociation constant was first defined with respect to dissociation of water into hydroxyl and hydronium ions. How then can one say that it is valid for an acidic solution, that is, even in ...
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1answer
1k views

Why does strong Lewis acid-strong Lewis base interactions prevail over hard-soft acid-base interactions?

In Pearson's paper, he mentions that strong acid-strong base interactions are more favourable compared to hard-soft acid-base interactions. He cites the example of $\ce{H+ + H- -> H2}$. In this ...
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0answers
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Hard and Soft Acid and Bases in terms of HOMO and LUMO

It has been given in a book and on Wikipedia that: hard bases have highest-occupied molecular orbitals (HOMO) of low energy, and hard acids have lowest-unoccupied molecular orbitals (LUMO) of high ...
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1answer
506 views

Does the addition of base to 3-pentanone give the cis or trans enolate?

I've spent several hours searching the WWW with entries like "stereoselective enolate formation" and similar ones, but I find almost only entries for Li-amide bases (LDA, LMTP) and no other bases like ...
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1answer
836 views

How to rationalise the protonation state of amino acids

I am learning about amino acids in various $\ce{pH}$ environments and how their groups are protonated or deprotonated in these environments. I don't need to mention a specific acid for my question, I ...
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1answer
294 views

Why there is a huge difference between the basicity of urea and guanidine?

The two molecules have very similar structures, but urea has a $\mathrm{p}K_\mathrm{b}$ of $13.9,$ while guanidine have a $\mathrm{p}K_\mathrm{b}$ of $0.4.$ If guanidine cation can be stabilized by ...
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197 views

Strength of weak acids and bases: Is methane better base than ammonia? [closed]

$\mathrm{p}K_\mathrm{a}$ of methane is $\sim 50$ and that of ammonia is $\sim 37,$ thus ammonia is a better acid than methane, which implies methane is a better base than ammonia. But I don't see how:...
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4answers
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The Reaction Between Nickel and Hydrochloric Acid

Having conducted an investigation involving multiple metals, I have found that nickel refuses to react with concentrated hydrochloric acid. I have even left the reaction overnight and still have seen ...
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1answer
46 views

Finding the volume needed to make a new pH

In the titration of 20.00 mL of 0.500 M HCl by 0.500 M NaOH, calculate the volume of 0.500 M NaOH required to reach a pH of 2.0. I have tried to change the 20.00 mL into the amount of substance (0.01 ...
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1answer
971 views

Equivalence point vs inflection point in the titration curve of a weak acid

Let's suppose we want to titrate a solution containing an unknown monoprotic and weak acid. We use a strong base, such as $\ce{NaOH}$. When the number (and moles) of hydroxide ions coming directly ...
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1answer
659 views

How do the strong acids dissociate?

In writing net ionic equations involving strong acids, one needs to know how strong acids dissociate. For example, the dissociation of $\ce{H2SO4}$: \begin{align}\ce{ H2SO4 &-> 2H+ + SO4^{2-}\\...
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1answer
3k views

Do acids without hydrogen taste sour?

I have heard that acids taste sour because of hydrogen (I don't really know exactly). According to the definition of acids: An acid (from the Latin acidus/acēre meaning sour) is a chemical ...
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1answer
55 views

How a titration curve is affected when a poorly soluble salt is formed?

Suppose that I have $\pu{100 mL}$ solution of strong acid, $\ce{HA}$, at $\pu{0.10 mol L^{-1}}$. This solution is titrated with a strong base solution, $\ce{BOH}$, at $\pu{0.10 mol L^{-1}}$. Suppose ...
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2answers
2k views

What is the reason for strong acids/bases dissociating in water?

I have read that the actual definition of a strong acid is one which will fully dissociate in water, so please do not turn the problem on its head when answering. It is also my understanding that ...
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2answers
818 views

Solid salts of hydronium ion

Are there any solids with hydronium ion in its crystal structure? If so, what are they? If not, why not? I understand there are hydroxide-containing solids and gels such as aluminium hydroxide but ...
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2answers
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Which base is stronger methylamine or propylamine?

Which base is stronger methylamine or propylamine? I know that it depends on the strength of inductive effect of alkyl group. Am I right? But how can I determine the difference between methyl and ...
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1answer
151 views

pH of very dilute acids

From doing some research on the site I have found that many people have posted about solutions of $\ce{HCl}$ where $[\ce{HCl}] = \pu{1e-8 mol dm-3}$ Here they are able to deduce $$[\ce{H+}] = \frac{[...
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0answers
211 views

Can the effect of resonance on acidity be generalised?

A basic trend for acid: if the conjugate base is more stable, then the acid has a lower $\ce{pKa}$. Therefore, it would quite intuitive to think that resonance in the conjugate base will make the acid ...
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1answer
575 views

How to determine if a reaction proceeds via SN1, SN2, E1 or E2 mechanism?

Give the main product and reaction type: SN1, SN2, E1 , E2. As the 1-bromohexane is primary and the nucleophile a strong unhindered base, the reaction should be a SN2 reaction. However, the solvent $...
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1answer
3k views

Why is LiOH a weaker base than NaOH [closed]

Why do LiOH is weak base as compared to NaOH even though it's hydration enthalpy is greater than Na?
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2answers
18k views

Using Le Chatelier's Principle to explain why percent dissociation of acids/bases increase with dilution

$$\ce{HA(aq) +H2O(l) <=>H3O+(aq) +A- (aq)}$$ Say the acid solution is currently in equilibrium. How would diluting the acid by adding water change the equilibrium position? Le Chatelier's ...
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1answer
908 views

Are hydrogen atoms in acetone molecule acidic?

My chemistry book says that acetone is aprotic, but I think that, since the conjugate base of acetone has possible resonating structures, the hydrogen atom must be free to move out as $\ce{H+}$ (as ...
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1answer
6k views

Why is Aluminium Chloride a Lewis Acid if it's an ionic compound?

In my textbook it says in the reaction $\ce{AlCl3 + Cl- -> AlCl4-}$, Aluminium Chloride ($\ce{AlCl3}$) has six valence electrons and accepts a lone pair from $\ce{Cl-}$, but wouldn't that mean the ...
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1answer
48 views

Is atom-clean aluminum active enough to react with alkali salts?

Thermally evaportated $\ce{Al}$ under high vacuum is free of oxidized species and highly active. But is it active enough to even substitute the alkali cationic metal in alkali salts, like $\ce{LiOH, ...
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0answers
944 views

Why does copper(II) sulfate react with ammonia?

We've done preparation of Tetraamminecopper(II) sulphate $\ce{[Cu(NH_3)_4(H_2O)_n]SO_4}$ using copper sulphate and 50% ammonia solution. Initially, a pale blue color of $\ce{Cu(OH)_2}$ appeared with ...
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908 views

Sodium percarbonate and sulfuric acid reaction

If an excess sulfuric acid is added to a detergent containing sodium percarbonate, would it be possible for the excess acid to react with hydrogen peroxide? I believe that the hydrogen peroxide will ...
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1answer
4k views

Is this reaction with H+ and OH− a possible reaction?

I am wondering about the reaction $\ce{H+ + O^2- -> OH-}$. Is it possible? I think this is not a possible reaction, because here a strong acid plus another particle reacts to a strong base. If it ...
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2answers
2k views

Under which criteria HNO3 is a concentrated or a diluted acid? [closed]

I would like to buy nitric acid to remove impurities of copper on an aluminum plate. I read that a 10% nitric acid will do the job. However I've also read that concentrated nitric acid is very ...
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62 views

Why isn't the ion-product constant the sum of the molar concentrations of H+ and OH-? [duplicate]

The Chemistry texts I have present the ion-product constant as: $$K_\mathrm w= 1.0 \times 10^{-14} = [\ce{H+}][\ce{OH-}]$$ Additionally I'm told that this constant at (25 °C) is an equilibrium. As ...
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2answers
2k views

Finding pH after dilution?

Assume that $\ce{pKa}$ is 4.76 Mix $\pu{50 mL}$ of $\pu{0.1M}$ $\ce{HA}$ and $\pu{50 mL}$ $\pu{0.1M}$ $\ce{NaA}$. This is solution (i). Calculate concentrations of $\ce{HA}$ and $\ce{A-}$, ...
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1answer
78 views

Do polyfluorosulfuric acids like H2SO2F4 exist?

I was thinking about a compound resembling $\ce{H2SO4}$ but more acidic. I thought to replace the 2 oxygens with 4 fluorine atoms getting $\ce{H2SO2F4}$, which might be more acidic. Does such a ...
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0answers
90 views

Primitive Technology - Production of NaOH

We need to produce NaOH with primitive Technology. This is Part 1 of my Gilligan's Island Challenge series (Part 2). You are stuck on an island with access to a beach, a forest, a river, a lake, and a ...
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1answer
8k 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{Na2CO3 -...

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