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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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5
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1answer
56 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 ...
1
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2answers
57 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{...
15
votes
4answers
18k views

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, ...
6
votes
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 ...
5
votes
3answers
21k 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 ...
2
votes
1answer
4k 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 ...
4
votes
1answer
102 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 ...
1
vote
1answer
69 views

Can acid-base reactions occur in a non-aqueous medium? [on hold]

The reaction between ammonia and hydrogen chloride to give ammonium chloride is a neutralization reaction, since ammonia acts as a base and hydrogen chloride acts as an acid. The reaction is usually ...
1
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0answers
50 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_\...
0
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0answers
59 views

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 ...
-4
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0answers
24 views

If you breath on KOH would you get K2CO3 + H2O as a product? [on hold]

In my AP Bio class we were looking at a reaction with CO2 and KOH and my biology teacher was wondering if breathing on KOH would produce solid K2CO3
0
votes
1answer
45 views

How to dispose of NaOH solution? [on hold]

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 ...
-3
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0answers
53 views

High temperature acids

Some of the proton production of an acid happens due to temperature and some of the proton production of an acid happens due to quantum tunnelling.But if we increase the temperature a lot the proton ...
-1
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0answers
34 views
8
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1answer
1k views

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 ...
-2
votes
0answers
18 views

Calculating the pH of a mixture of glycine and sodium hydroxide [on hold]

What is the pH of a total 500 ml solution of 0.20 mol of glycine and 0.025 mol of NaOH? I believe the pKa of the amino group is approximately 9.6; the pKa of the carboxylic acid group is 2.8. Are ...
0
votes
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 ...
2
votes
1answer
161 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'...
6
votes
3answers
1k views

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 ...
1
vote
1answer
37 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?
2
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0answers
11 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 ...
-2
votes
2answers
88 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 ...
-1
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0answers
19 views

Calculate pH of borax-boric acid buffer solution? [on hold]

In a recent experiment I made a borax-boric acid buffer solution by dissolving 9.535 g of borax in water and adding 92 ml of 0.1 M HCl. The pH of this solution was given as 9.00. I then took 20 ml of ...
-3
votes
0answers
24 views

Need help, thanks [closed]

A concentrated strong acid is added to a solid mixture of 0.015mol samples each of Fe(OH)2 and Cu(OH)2 placed in 1.0L of water. At what values of pH will the dissolution of each hydroxide be complete? ...
0
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0answers
36 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 ...
0
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0answers
72 views

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 ...
-1
votes
0answers
32 views

Boiling nitric acid and gold plating

I was watching a YouTube video "Home Brew Gold Plating" by Cody'sLab and had a few questions. In the video to dissolve the gold first he creates a mixture of $\ce{HCl}$ and $\ce{HNO3}$ (aqua regia). ...
3
votes
1answer
124 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: ...
-1
votes
2answers
26 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 ...
0
votes
3answers
79 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 ...
5
votes
3answers
87k 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 ...
0
votes
0answers
31 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 ...
0
votes
2answers
173 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 ...
3
votes
1answer
138 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 ...
1
vote
1answer
45 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 ...
8
votes
2answers
11k 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?
1
vote
1answer
48 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 ...
-1
votes
1answer
36 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 ...
1
vote
0answers
524 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 ...
0
votes
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 ...
1
vote
1answer
35 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: ...
0
votes
0answers
50 views

Can pure water dissolve metal? [duplicate]

Recently I've fallen for the following clickbait from Business Insiders: A golden chamber buried under a mountain in Japan contains water so pure it can dissolve metal, and it's helping scientists ...
3
votes
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 ...
1
vote
1answer
69 views

Why is the pH level of carbonation loss decreasing then increases afterwards?

We have done an experiment of the titration of unsealed sprite soda to find the amount of carbonic acid being loss on various duration (0 to 1 hour), due to decrease pressure. The calculation was to ...
7
votes
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 ...
0
votes
1answer
300 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 = ...
3
votes
1answer
851 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 ...
0
votes
0answers
50 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 ...
11
votes
1answer
39k 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,...
1
vote
2answers
6k 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 ...