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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20 views

Ka for reaction from tables [duplicate]

For the reaction below: NH4+ + H2O -> NH3 + H30+ I have the following values from a table to use: And in the solution manual they tell me to use the Ka for this reaction. Why is this? Why do we ...
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1answer
8k views

Why is NH3 a stronger base than PH3,AsH3,SbH3,BiH3 and McH3? [duplicate]

I know that the orbitals of nitrogen overlap better with the 1s orbitals of hydrogen and that the orbitals of moscovium overlap worse with the 1s orbitals of hydrogen, but I don't know how to use this ...
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1answer
89 views

pKa of phenols using UV-Vis spectroscopy

I have done an experiment where I dissolved four different substituted phenols in acidic, basic, and buffer solutions, and recorded the UV-Vis spectra for each. I'm supposed to pick a wavelength where ...
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1answer
952 views

Comparing acidity of anilinium ion and para-fluoro anilium ion

Which of these compounds - anilinium ion and para-fluoro anilium ion - is more acidic? I thought the answer would the be first one since $\ce{-F}$ is an ortho-para activating group, so the electron ...
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1answer
155 views

Can acid-base reactions occur in a non-aqueous medium?

To better illustrate my question, allow me to refer to the case of ammonium chloride, formed through a classic acid-base reaction. The reaction between ammonia and hydrogen chloride to give ammonium ...
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2answers
321 views

Why acidity of p-methoxybenzoic acid is more acidic than p-hydroxybenzoic acid?

I know +M effect of $\ce{OCH3}$ is more than $\ce{OH}$, but in my book (ALLEN General organic chemistry), it is given that $\mathrm{p}K_\mathrm{a}$ of para-substituted benzoic acid containing $\ce{...
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4answers
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Acidity order of nitrophenols

As in other posts I have seen and learnt that, if one is given four compounds, namely para-nitrophenol, ortho-nitrophenol, meta-nitrophenol and phenol and is told to arrange them in order of acidity, ...
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2answers
3k views

Why is ortho-hydroxybenzoic acid more acidic than its para-isomer?

Why is ortho-hydroxybenzoic acid $(\mathrm{p}K_\mathrm{a} = 2.98)$ more acidic than its para-isomer $(\mathrm{p}K_\mathrm{a} = 4.58)$? March's Advanced Organic Chemistry (7th ed) gives the reason to ...
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3answers
22k views

Acidic strength of para substituted benzoic acids

Comparing the acidic strength, the nitro-substituted group is definitely more acidic. This can be reasoned by fact that a higher delta positive charge which develops on the H due to the strong -M ...
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1answer
5k views

Why m-hydroxybenzoic acid has higher acidity then p-hydroxybenzoic acid?

Why m-hydroxybenzoic acid has higher acidity than p-hydroxybenzoic acid? I have a reasoning that since hydroxy group is an activating group, then it increases the electron density on its para ...
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1answer
357 views

What is the pKaH of pyrrole?

I am supposed to say what is more basic and I ran into a problem. I would like to ask if anyone has any idea what is the correct $\mathrm{p}K_\mathrm{a}\ce{H}$ value of pyrrole. I know it is easy to ...
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69 views

What is the pH and pKa relationship of LaCl3 in water and its precipitant La(OH)3?

In light of this question and its answers, I hope to get some insights into the $\mathrm{pH}$ of $\ce{LaCl3}$ in water and its $\mathrm{pH}$ relationship to $\ce{La(OH)3}$ precipitant's $\mathrm{p}K_\...
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Oxidation of certain acids by potassium permanganate

Why does potassium permanganate oxidize formic acid and oxalic acid, but has no reaction with benzoic acid and acetic acid? The reactions were heated in a water bath (~70-80 °C). Oxalic acid had ...
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1answer
401 views

How to dispose of NaOH solution? [closed]

I have a range of sodium hydroxide solutions with different concentrations. (from 1.0 mol dm^-3 to 0.5 mol dm^-3). The max volume of each is 100ml. How can you easily dispose of these? Can I pour them ...
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1answer
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Comparing pKa of hydrocarbons

We have to compare their acidic strength, and we know acidic strength is directly proportional to stability of the anion. So the first compound is more acidic due to its being aromatic after ...
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2answers
1k views

How to calculate the composition of a borate buffer with a defined pH using the Henderson-Hasselbalch equation?

I am struggling with what appears to be an extremely easy pH problem that uses the Henderson-Hasselbalch equation. The problem and answer provided by the book is given below. I understand where the ...
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1answer
213 views

Show the acid nature of hydrogen sulfide

We are studying the chalcogens at school. I should prove (show) the acid nature of $\ce{H2S}$ by writing two chemical interactions. I am really sorry if the terms I am using aren't the right ones. It'...
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3answers
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Why does adding salt to water reduce the pH?

I recently heard someone claim that adding table salt to vinegar caused HCl to form which helped them clean coins - clearly not the case - however I thought I'd disprove it by doing an experiment. So ...
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1answer
41 views

Reduction of amides with lithium aluminium hydride [closed]

Since $\mathrm{p}K_\mathrm{a}$ of primary amides are close to alcohols, will there be an acid-base reaction between amides and $\ce{LiAlH4}$ besides reduction?
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19 views

Acidic strength of phenol derivatives

While comparing the strengths of o-nitrophenol and p-nitrophenol, p-nitrophenol is found to be more acidic. The reason I studied for this is $\ce{H}$-bonding in o-nitrophenol which makes the acid more ...
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2answers
112 views

Why aren't plastic bottles of coca cola full of microplastics?

My understanding is that disposable plastic water bottles should not be reused or used at all after some time, because the bottle will eventually leech microplastics into the water. Since coca cola is ...
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51 views

Hydronium ion concentration to compare pH values

I'm having a bit of trouble with this question: Which has a higher $\mathrm{pH}$ value, $\pu{0.001 M}$ $\ce{HCl}$ or $\pu{0.1 M}$ $\ce{CH3COOH}$ $(K_\mathrm{a} = \pu{1.8E-5})?$ I have calculated ...
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How can you use indicator titration to determine the pH of a complex solution like ocean water if at all

Could you measure the pH of ocean water by using a strong acid-weak base titration? I was thinking that you could set up a standard titration with ocean water as the "unknown", and drip the known HCl ...
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1answer
145 views

Mechanism for the reaction between trisilylamine and hydrogen chloride

In Concise Inorganic Chemistry by J. D. Lee (adapted by Sudarsan Guha), in the chapter "Chemical Bonding", under the topic "Back Bonding with Nitrogen as a donor atom" the following reaction is given: ...
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33 views

How do you know is a solution is acid or basic when you dissolve a weak acid/base? [closed]

If I dissolve the weak acid HCN into water, I get a solution of oxonium and CN ions and since there is an equilibrium there is more HCN left. So I thought CN ions can consequently react with water to ...
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3answers
84 views

Confusion on ion product of water

The ion product of water is defined as $$ K_w = [\ce{H+}][\ce{OH-}] $$ and in pure water $ [\ce{H+}] = [\ce{OH-}]= 1.0 \times 10^{-7}$ and $ K_w = 1.0 \times 10^{-14}$. It is said that if we dissolve ...
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3answers
96k views

Reaction between NaOH and CO2

So I wanted to know what the reaction between sodium hydroxide and carbon dioxide can be, and upon research I got 2 answers. The first one is $$\ce{CO2 + NaOH(aq) -> NaHCO3(aq)}$$ and the second ...
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48 views

How to calculate Revelle factor using only pH, DIC and TAlk for seawater?

I have the temperature, salinity, $\mathrm{pH},$ dissolved inorganic carbon (DIC) and total alkalinity (TAlk) values for an estuarine water sample. I want to calculate the Revelle factor. The Revelle ...
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2answers
190 views

How to find the ionization constant of an unknown weak acid?

A $\pu{0.45 M}$ solution of a weak acid, $\ce{HX}$, has a $\pu{pH}$ of $4.5$. What is the ionization constant, $K_a$, of the acid? $\ce{[HX]}$ is already given as $\pu{0.45 M}$. $\ce{[H+]}$ is given ...
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1answer
139 views

Impossible pH For Aqueous Weak Acid Solution

An aqueous solution of $\ce{HCl}$ has a $\mathrm{pH}$ of $0.00$ if $[\ce{H+}] = 1.00 \; \mathrm{M}$. I tried to see if an aqueous solution of acetic acid could have a $\mathrm{pH}$ of $0.00$, given ...
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1answer
69 views

Acid-base titration: Unknown base in burette or flask?

While finding the concentration of $\ce{NaOH}$ via titration with $\pu{0.05M}$ Oxalic acid solution (in our lab) we put NaOH in the burette whereas added phenolphthalein to oxalic acid in titration ...
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2answers
12k views

Reactions of alkynes with sodium/ammonia vs sodium amide

What happens when alkynes react with sodium in ammonia ($\ce{Na/NH3}$), or when they react with sodium amide ($\ce{NaNH2}$)? Are these two sets of conditions different?
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1answer
80 views

When disolving a iron pill for titration, why do I use sulfuric acid instead of nitric or hydrochloric acid?

In a titration to decide the iron content of a pill we dissolved the iron in sulfuric acid and then titrated it with cerium(IV) sulfate. But I just wondered what's wrong with using nitric and ...
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1answer
39 views

The reaction of an oxyacid with water [closed]

I read in my book this: $$\ce{H2SO3 + H2O -> HSO3- +H3O+}$$ while I rather would write (not balanced): $$\ce{H2SO3 + H2O -> 2 H+ + SO3^2- + 2 H2O -> SO3^2- + 2H3O+}$$ I mean I don't ...
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0answers
731 views

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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2answers
70 views

Finding pH of acid in water [closed]

How would you find the pH of an acid dissolved in water? Would you need to take the fact that the pH of water is already 7 into account and go on from there? Say, for example, that you add 0.0500 mL ...
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1answer
52 views

Type of reaction between (+)-bis salt of (+)-phenylsuccinic acid and HCl [closed]

Im confused about what type of reaction occurs between the (+)-bis salt of (+)-phenylsuccinic acid and HCl. Would this be considered an acid base reaction or a neautralization reaction? MY THOUGHTS: ...
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1answer
2k views

Acidic and alkaline salt solutions: why do some salt form acid/bases while others don't [closed]

I have a question regarding salts and their solutions. How come some salts, like sodium carbonate and ammonium chloride, produce acids/bases when dissolved in water? Moreover, how can you predict ...
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3answers
14k views

Why amino acids (Zwitterion) become either negative or positive at low and high pH solutions?

The amino acids are Zwitterions. In neutral pH, an Amino acid's amino group has a postive charge and Carboxyl group has negative charge. They cancel each others charge thanks to the $Hydrogen$ that's ...
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1answer
329 views

Peptide at pH=1

In the following peptide: I want to know the net charge of the peptide at pH=1. According to me the as the solution is acidic so every nitrogen will get protonated. Hence the number of charge = ...
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1answer
881 views

Calculating charge of amino acids (am I doing it right?)

Please consider this picture of a peptide chain: I've done some examining on the different amino acids and concluded that the chain is as follows: Lys-Leu-Gly-Ser-Citrullin (variant of arginine). I ...
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72 views

pKa values for amino acid

To calculate the pI value, we take the average of the pKa values from the 2 groups that result in a net charge of 0. For that to happen, the pKa values should be at the midpoint of titration where ...
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1answer
42k views

How do I calculate the isoelectric point of amino acids with more than two pKa's?

For most amino acids, the $\mathrm{pI}$ is simply the mean of the amino and carboxyl $\mathrm pK_\mathrm a$'s. However, for tyrosine and cysteine, which have more than one $\mathrm pK_\mathrm a$ value,...
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2answers
8k views

Why do vinegar and other acids remove rust?

I have started a project on restoring a very rusty knife. I had used vinegar to remove the rust. A question dawned on me: why does vinegar remove rust? So being the thoughtful person I am, I googled ...
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0answers
34 views

Calculating pH of a saturated weak acid/base solution [closed]

How can you calculate the $\mathrm{pH}$ if you know for example the $\mathrm{p}K_\mathrm{a}$ or $\mathrm{p}K_\mathrm{b}$ value of a weak acid/base and how much acid/base can dilute in water. Let's ...
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0answers
63 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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3answers
232 views

n-Factor of phosphorous acid

It's very confusing that while $\ce{H2SO4}$ has an $n$-factor of 2, whereas $\ce{H3PO3}$ has $n$-factor 2 instead of 3. Many tried explaining it to me by molecular structures, but I don't know how to ...
2
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1answer
210 views

Is barium sulfate soluble in dilute mineral acid?

I have read that $\ce{BaSO4}$ is soluble in $\ce{HCl}$ , but I am not sure whether this works for dilute acid as well. The reaction is - $\ce{BaSO4 + 2 HCl ->BaCl2 + H2SO4}$
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2answers
2k views

Will cinnamaldehyde undergo self-aldol condensation?

Will cinnamaldehyde undergo self-aldol condensation? My book says it won't, but since it has an α-hydrogen, I'm confused.
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1answer
4k views

Why is lemon mixed with water considered alkalizing water?

The benefits and facts of alkaline water are often skewed due to the marketing of companies and uneducated hype for the innocent idea of unlimited potential. I wanted to know the specific reactions ...

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