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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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Why is antimony pentafluoride a stronger Lewis acid than phosphorus pentafluoride or arsenic pentafluoride?

How can these relative reactivities as a Lewis acids be rationalized: $$\ce{SbF5 > AsF5 > PF5}$$ One simple argument could be the size of the $\ce{Sb}$-center: Because it is bigger than for ...
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Comparing the basicity of benzamide and acetamide

What if we were asked to compare the basicity of benzamide and acetamide? Which one of them would be more basic? I read somewhere on the internet that benzamide must be more basic than acetamide due ...
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pH throughout a titration

Estimate the $\ce{pH}$ of the solution that results when $\ce{75.0 mL}$ of $\ce{0.275 M HCl}$ is added to $\ce{50.0 mL}$ of $\ce{0.275 M Na2HPO4 (aq)}$. My book gives the successive $\ce{Ka}$ values ...
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1answer
126 views

Why doesn't pH = pKa1 in the buffer zone for this titration?

Below is an image from my textbook representing the titration curve for the titration of $5.00\ \mathrm{mL}$ of $0.010\ \mathrm M$ $\ce{H2S2O3}$ with $0.010\ \mathrm M$ $\ce{KOH}$, which has $\mathrm ...
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1answer
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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 ...
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1answer
35 views

Acid neutralization [closed]

I am working on a biogas plant, digester volume 3000 liter, right now pH condition is acidic at 4.00 my requirement is to maintain pH to 6.50 to 7.20 what should I do? some suggestions are there like, ...
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Order of lewis acidity for BBr3, BCl3, BMe3, BH3, BPh3?

In case of $\ce{BCl_3}$ vs $\ce{BH3}$, which one is the controlling factor? 1) Is it p-pi p-pi interaction in $\ce{BCl_3}$ that makes it weaker than $\ce{BH3}$? 2) Or is it the -I effect of $\ce{Cl}...
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123 views

Comparision of acidic strength of benzoic and peroxy benzoic acid [closed]

Out of the two which one is stronger acid ?
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1answer
69 views

Can an ant etch a hole in a tent with formic acid?

Given a polymer foil tent, could ant's formic acid help to etch a hole in it? I thought of a polyester or polyamid foil. If one ant's acid is not enough, they come as team. This is not a theoretical ...
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28 views

How to determine charge of compounds in solution with many amphoteric functional groups?

I am curating a metabolic model that has compounds such as NADH/NADPH/Etc. that have multiple ionize-able hydrogens. Normally with amino acids there are only a few hydrogen with varying pKas that ...
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1answer
44 views

Why does Ca(CH3CH2CH2COO)2 dissolve in HCl and not in NaOH? [closed]

I do not understand why a strong base, such as NaOH would not dissolve a solid such as this. There would be a double displacement in which you form Ca(OH)2 and NaCH3CH2COO (aq). Why would HCl ...
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What is the “coefficient of ionization” or “ionization coefficient”?

The question got bumped and I looked at it. The OP seems to use the two terms coefficient of ionization and ionization coefficient interchangeably and assigns the variable $\alpha$. The problem is in ...
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1answer
71 views

How to calculate the concentrations of conjugate species present in the solution of diprotic acid?

Calculate the concentration of‏ $[\ce{SO_3^-^2}]$ present in 0.010M solution of $\ce{H_2SO_3}$ in pure water? ($Ka_1=0.017)$, ($Ka_2=10^{-7.19}$) I found this approach in reference text for solving ...
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1answer
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Why don't soluble gases that evolve in a reaction remain in solution?

Take for instance the following process: $$\text{2NaCl}_{\ (s)} + \text{H}_2\text{SO}_{4 \ (aq)} \to \text{2HCL}_{\ (g)} + \text{Na}_2\text{SO}_{4 \ (aq)} $$ Why does the evolved gas leave the ...
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1answer
771 views

Why is ammonia less acidic than terminal alkynes?

Here's a picture from Organic Chemistry by Solomons, Fryhle & Snyder : Why is it that ammonia is less acidic than terminal alkynes even though water, and even alcohols, are more acidic than them?...
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1answer
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% Purity Calculation [closed]

An impure sample of calcium oxalate with a mass of 0,803g, is titrated with 15,70cm3 of a 0,101 potassium permanganate How do I calculate the % purity of the calcium carbonate in the original sample
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EQPt pH of a Monoprotic Acid-Base Titration: Product of Molarites Over Their Sum

Context The Henderson-Hasselbalch equation is as follows. $$pH=-\log\big(K_a\big)+\log\bigg(\frac{[A^-]}{[HA]}\bigg)$$ One may follow its derivation in order to understand how it came to be, yet ...
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1answer
862 views

Which formula can be used to calculate the exact hydronium concentration present in sodium hydrogen carbonate solution?

Which formula can be used to calculate the exact hydronium concentration present in sodium hydrogen carbonate solution ? $$\ce{[H3O+]}=\sqrt{K_\mathrm{a1}K_\mathrm{a2}}$$ $$[\ce{H3O+}]=\sqrt{\frac{...
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Why is perchloric acid stronger than perbromic acid? [duplicate]

Since chlorine has a larger electronegativity than bromine, why is perchloric acid a strong acid, while perbromic acid is not? We clearly see that electronegativity affects an acid's strength with ...
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1answer
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Ionproduct of Water [duplicate]

The ionproduct of pure water is well known to be $$ K_{\rm W} = \left[ {\rm OH^-} \right] \left[ {\rm H_3O^+} \right] = 10^{-14} $$ at some standard conditions (I think 25°C). However having some ...
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3answers
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Why do electron donating groups decrease the acidity of aromatic carboxylic acids?

If we look at the resonance structures of benzoate anion, we would see that some amount of positive charge is present on the ring and this charge can get delocalised on the ring, like this: Now, if ...
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1answer
61 views

Is it correct to say H2SO4 behaves like an acid in this reaction? [closed]

I came across this equation : $$\ce{ZnCO3 + H2SO4 → ZnSO4 + CO2 + H2O}$$ I wanted to know if $\ce{H2SO4}$ behaves like an acid in this reaction? How do we generally determine if a compound acts as an ...
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48 views

How much muriatic acid to dissolve cinder block? [closed]

Can a cinder block be dissolved in hydrochloric (muriatic acid) ? Also if it can then how much hydrochloric acid will be needed ?
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Confusion About Acid/Bases That Don’t Follow the Arrhenius Definition [closed]

I understand that acidity is merely a reflection of how many free hydrogen ions are in water, and basisicity is just a reflection of the number of hydroxide ions, but I don’t understand how this ...
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549 views

Citric acid rust removal and neutralization

I'm currently removing rust from steel with citric acid dissolved in water. I generally use a wire brush as the final treatment to remove any surface rust that the acid loosened up. The pieces under ...
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1answer
655 views

How to calculate pH of the Na2Co3 solution given ambiguous Ka values

This is the exact question i faced on 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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2answers
226 views

Phenol and Deuterated Sulphuric Acid

What happens when phenol reacts with $\ce{D2SO4}$ in presence of $\ce{D2O}$? How many hydrogens in total are replaced by deuterium? Is the hydrogen of the hydroxyl group and three hydrogens ortho ...
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1answer
546 views

Group 15… Lewis Acid, Lewis Base or Not At All?

I am a long-time reader of this forum, but this is my first time post. I am a chemistry undergrad with a question about Lewis acidity or basicity of Group 15 compounds. I know Lewis acids act as an ...
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74 views

About nitrogen acidity in function groups

I have a compound and it has several nitrogen atoms. I wish to know how do we differentiate between the basic and acidic nitrogens? This is an example compound:
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Is there a thermodynamic explanation for how a substance behaves based on its pKa and the solution’s pH?

If the pH of the solution is lower than the pKa of the compound, then the compound will be protonated, because pH is a measure of the concentration of protons, and low pH means a high proton ...
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108 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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1answer
474 views

Is an acid strong when its conjugate base is strong or weak? [duplicate]

It is often said that stronger acids have weak conjugate bases and vice versa. Yet also in organic chemistry if an acid is proven to have a stable conjugate base it is said to dissociate more, which ...
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2answers
409 views

Calculate pH of a weak acid and weak base neutralization reaction

I'm an industrial pharmacist needing some help with some chemistry basics. I'm trying to calculate the theoretical pH of an effervescent preparation containing 2 mmol citric acid ($\ce{H3C6H5O7}$), 4 ...
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1answer
55 views

Why is there only a slight change in pH when soda loses its fizz?

I did an experiment for my chemistry class and did a control with sparkling water and the pH increased by a significant amount, but when done with sodas like cream soda, coke, or 7 Up, the pH change ...
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Do bases undergo dissociation or ionisation in aqueous solution?

What do bases undergo when dissolved in water: ionisation or dissociation or both? Some books say ionisation while others say dissociation. What is the correct answer?
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Why galvanic corrosion by sulphuric acid has a whitish appearance?

This is a picture of pearlitic cast iron engine liner which was corroded from the presence of sulphuric acid on the combustion products. What is the cause of the whitish appearance?
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What is the point of proposing newer, broader acid and base theories to label even more substances as “acid” or “base”? [duplicate]

So first came the Arrhenius definition, then the Brønsted-Lowry theory, and after that, the definition of Lewis. All "trying" to cover more and more substances and label them as either acid or base. ...
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Maximum possible hypochlorite concentration from electrolysis?

For reference, "electrochlorination" is just the electrolysis of a simple solution of water and table salt (NaCl) followed by reintroducing the chlorine gas produced. But, the Wikipedia article on "...
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Calculating the pH of a weak acid from the Kb of its conjugate base

I'd start off by saying it's been many years since I was in chemistry lessons and have forgotten much, but recently I have had to relearn a lot of basic chemistry. The following doesn't really impede ...
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2answers
517 views

Buffer Solution with Strong Acid?

I was thinking: Could we could make a strong acid-strong base buffer solution? Take, for instance, a mixture of 1 L $\ce{HCl}$ (0.1 M) and 1 L of aqueous salt, $\ce{Na_2SO_4}$ (also 0.1 M), note that $...
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Using proton affinity to compare relative basicity of two molecules

I have a paper citing a proton affinity value for a heterocyclic molecule at ~1150 kJ/mol. Since I am unused to working with proton affinity, I would like to find a reference base to orient myself on ...
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How does H2SO4 dissociate?

Apologies for this extremely basic question, I'm just beginning with Chemistry so please don't be too harsh on me. My book says that sulfuric acid, $\ce{H2SO4}$, dissociates in its ions following ...
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435 views

Finding the pH value of HF [closed]

Find the pH value of HF. $pH = -\log[H+]$ for strong acids $pOH = -\log[OH-]$ for strong bases $pH = 1/2(pKa - \log C)$ for weak acid $pOH = 1/2(pKb - \log C)$ for weak base HF is weak acid so $...
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What happens to an acid when it completely dries out?

What happens to an acid when it completely dries out? Does it stop being acidic? And if there is a base there also, does it give back it's H's?
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1answer
39 views

How come one of the hydroxides in the phosphate group are more acidic than the other?

Three phsiologically relevant $\mathrm{p}K_\mathrm{a}$ values are associated with psilocybin: 1.3, 6.5 and 10.4. Suggest the appropriate charged species and mark the $\mathrm{p}K_\mathrm{a}$ values ...
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1answer
197 views

Why do my equilibrium calculations on this HF/NH4OH buffer system not match those in literature?

I've been trying to reproduce Figure 2 from this research paper (full text available). The Problem However I can't seem to get the same values as in the paper. I did the math both by hand and with ...
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1answer
94 views

Can someone confirm and/or correct my logic regarding this mechanism?

In the picture, Ethyl 2-oxocyclopentanecarboxylate (I) reacts with ethyl 2-(4-chloromethylphenyl)propionate (II) in the presence of KOH in hot DMF to afford ethyl 2-[4-(1-ethoxycarbonyl-2-...
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1answer
110 views

Comparing the pKb of piperazine and methylpiperazine

In comparison to piperazine, the inductive effect will cause the $\mathrm{p}K_\mathrm{b}$ of methylpiperazine to be: The answer given is that the $\mathrm{p}K_\mathrm{b}$ will be lower due to ...
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1answer
115 views

What are the predominant acids in sphagnum peat moss?

I'm trying to figure out what the predominant acidic substances in peat moss are. Peat moss is said to have a pH of approximately 4.0. So, I'm curious what is making it acidic. I know not all acids ...
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How to check which compound is amphotheric,neutral,basic or acidic among - (ZnO ,Al2O3,PbO,Cr2O3,BeO,SnO,CO2,CO,NO,NO2)? [closed]

A lot of questions are asked on the nature(acidic,basic,neutral) of compounds in exam.How can I solve such questions ? without memorizing its nature is there any way to solve? please explain how to ...