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 isn't Kw = ([H+][OH-]) / [H2O], when H2O is the reactant?
For the hypothetical reaction:
$ A ⇌ B + C$
the equilibrium constant expression is written as
$\ K= \frac{[B][C]}{[A]} $
So, why is $ K_w $ written as:
$ K_w = [H^+][OH^-] $
I would expect:
$ ...
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0answers
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Why highly electropositive elements form strong bases?
I know that elements like sodium form hydroxides which completely dissociate in water but why do they dissociate more than others like magnesium hydroxide?
Does reactivity has a role here ?how?
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Electrophilic base / nucleophilic acid / basic electrophile / acidic nucleophile
What I was understanding is that all bases are nucleophiles and acids are electrophiles means the condition for them is same and all nucleophiles are basic and all bases are nucleophiles and same for ...
1
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1answer
47 views
Why is the carboxyl proton in salicylic acid more acidic than the phenol proton?
I know I'm just wrong about this but I'd appreciate some help seeing why. It seems to me like the phenol proton in salicylic acid should be more acidic than the carboxyl proton. When I try to draw ...
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1answer
48 views
Conditions for the reduction of dichromate by manganese(II) to chromium(III) [on hold]
The unbalanced redox reaction
$$\ce{Mn^2+ + Cr2O7^2- -> Mn^3+ + Cr^3+}$$
occurs in what type of condition?
(a) Acidic
(b) Basic
(c) Neutral
(d) Indeterminable
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2answers
54 views
Finding pH of acid in water [on hold]
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 ...
0
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1answer
25 views
Appropriate container for storing/keeping chromic acid? [on hold]
I am planning to make chromic acid, however I the information for keeping chromic acid are conflicting. Can it be stored in a glass bottle even though it's used as a glass etchant? Also I saw some ...
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0answers
23 views
Why does ammonia have a pKa of 32.5 at −33 °C?
According to Wikipedia, ammonia has a $\mathrm{p}K_\mathrm{a}$ of $32.5$ at $\pu{-33 °C}.$ Why does it say that? Is it a typo? Isn't anything above $12$ is a very strong base? And both bases and ...
1
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1answer
52 views
Why CO2 is not reducing the pH of NaOH as the way it is expected
I am using $\ce{CO2}$ for the reduction of pH of $\ce{NaOH}$ solution ($\pu{2.5g}\; \ce{NaOH} + \pu{250ml}\; \ce{H2O}$, with $\mathrm{pH}\; 13+$).
I am introducing $\ce{CO2}$ with different dosages ($\...
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1answer
29 views
Titration/ Separating Soluble Salts/ NaHSO4
When performing titration between NaOH and H2SO4, both Na2SO4 and NaHSO4 are formed (both are soluble in water), is there any method to obtain crystals of NaHSO4? (Maybe by separating two soluble ...
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1answer
21 views
Phenolphthalein Indicator mixed with base that first turns pink and then clear
What occurs in the following situation: After adding 2 drops of Phenolphthalein Indicator (an indicator that turns bases pink and stays clear for acids,) into a unknown solution, the solution turns ...
1
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1answer
63 views
Preparation of acetate buffer from sodium acetate and hydrochloric acid
A $\pu{1.0 L}$ buffer solution of $\mathrm{pH}~4.43$ is made up of $\pu{0.30 M}$ sodium ethanoate and $\pu{0.20 M}$ $\ce{HCl}$ solutions. Calculate the volume of sodium ethanoate and $\pu{0.20 M}$ $\...
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votes
1answer
29 views
Can sulfuric acid attack a hydrocarbon/paraffin? Under what conditions? [on hold]
Sulfuric acid can attack benzene and other hydrocarbons (when mixed with hydrogen peroxide). Also, chlorine gas and bromine can replace hydrogen(s) in hydrocarbons like methane, ethane, propane,butane ...
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0answers
89 views
Is propanoic acid mono-, di- or triprotic? [closed]
Is propanoic acid $\ce{CH2CH3COOH}$ diprotic or triprotic? I understand what each are but this one is a bit confusing.
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0answers
13 views
Why does phosporic acid have low pH but is still considered to be a weak acid? [closed]
Why does phosporic acid have low pH but is still considered to be a weak acid? How does phosphoric acid (H3PO4) differ in dissociation constant when the temperature is changed? I need the answer for ...
0
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0answers
20 views
Can someone help me explain this in terms of pKa? Does it relate to why the reaction must be heated? [closed]
$\ce{HBr}$ is a strong acid that protonates water extensively to give the hydronium ion, $\ce{H3O+}$. Because a hydronium ion is a weaker acid than undissociated hydrobromic acid, it is unable to ...
0
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2answers
25 views
Does salt hydrolysis takes place in buffer solution? [closed]
I am a bit confused whether hydrolysis of salt takes place in buffer solutions because the books which I read doesnt consider them.But I think since weak base or weak acid salt is present hydrolysis ...
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1answer
53 views
Not a chemist, needs help with a calculation regarding addition of HCl to sodium formate solution [closed]
As stated I am not a chemist, but I need help on a question I have.
Assume I have a Formic acid 75% and I add between 5-10 kg to 1.000 liter of water. If I wanted to add sodium formate and HCl 37% to ...
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0answers
53 views
Can a universal indicator turn colorless?
I learned that litmus paper could be bleached by chlorine to turn colorless. I’m wondering if any chemical substances can react with all the components of a universal indicator such that it turns ...
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1answer
45 views
Why do strong polyprotic acids not dissociate completely, whereas strong bases with multiple (OH)- groups do?
$\ce{H2SO4}$ is a strong acid, which follows the reaction
$$\ce{H2SO4 -> HSO4- + H+}$$
Not
$$\ce{H2SO4 -> SO4^2- + 2 H+}$$
However,
$$\ce{Ba(OH)2 -> Ba^2+ + 2OH-}$$
Is there a reason why ...
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0answers
26 views
Are primary or tertiary carbanions more basic?
I am not sure about the exact IUPAC protocol for this, but I'm imagining a isobutane where the hydrogen disassociates leaving the lone pair on the tertiary carbon.
I want to compare it's Bronsted ...
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0answers
34 views
Finding ionic radii from solubility data and density
$\pu{5.35 g}$ of a salt $\ce{ACl}$ is dissolved in $\pu{250 ml}$ of solution. The $\mathrm{pH}$ of the resultant solution was found to be $4.85.$ Find the ionic radius of $\ce{A+}$ and $\ce{Cl-}$ if ...
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1answer
48 views
Can concentrated sulfuric acid oxidize iron(II) to iron(III)?
Can concentrated (18 M) $\ce{H2SO4}$ oxidize $\ce{Fe^2+}$ to $\ce{Fe^3+}?$ Or does it actually block the oxidation? I read in some forum somewhere that in order to prevent $\ce{Fe^2+}$ from being ...
4
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1answer
56 views
What is the reaction between piperine and concentrated sulfuric acid?
Piperine was chemically characterized by reaction with acids. This was done by dropping concentrated $\ce{HNO3},$ $\ce{HCl},$ and $\ce{H2SO4}$ to a sample of piperine. Both $\ce{HNO3}$ and $\ce{HCl}$ ...
2
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2answers
200 views
Help in drawing resonance structures in case of polybasic acids
While drawing resonance structure of dibasic or tribasic acid, e.g. should I take out two $\ce{H+}$ (in dibasic) or three $\ce{H+}$ (in tribasic) together or one by while drawing resonance structure?
...
3
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0answers
28 views
acid strength: Periodic trends vs delocalisation, which one is more important
In 1st year chemistry questions, the concept of acid strength is often introduced to students including the 3 factors that provide a heuristic explanation for most of the common acids and conjugate ...
2
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0answers
57 views
Acidic strength order of mineral acids in acetic acid
Explain this acidic strength order $\ce{H2SO4} > \ce{HCl} > \ce{HNO3}$ in acetic acid.
My Attempt
Stability of conjugate base is proportional to the acidic strength of acids in acetic acid.
$\...
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1answer
33 views
Vinegar salt reaction to produce acid; does it matter what type of vinegar I use
I am trying to get get hydrogen chloride gas by using the reaction sodium chloride + vinegar = HCl(g) + sodium acetate, does it matter what type of vinegar I use eg apple cider vinegar, malt vinegar; ...
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1answer
65 views
Will distillation do the job of purifying the water?
I asked about my sophisticated water purification system for a generation ship on Worldbuilding Stack Exchange, and somebody mentioned this:
If you're gonna go to all the trouble of distilling it, ...
2
votes
1answer
40 views
How to determine if a compound is a strong, weak, or non-electrolyte? [closed]
I'm stuck on questions asking whether a given chemical formula is a strong or weak electrolyte in an aqueous solution. I did some research online, but could not get a specific solution that I could ...
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0answers
30 views
Hydrogen bonding in o-nitrophenol versus o-nitobenzoic acid
p-nitrophenol is more acidic than o-nitrophenol because of hydrogen bonding in the latter. If I apply the same logic, then o-nitrobenzoic acid should be less acidic than p-nitrobenzoic acid. However, ...
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0answers
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The most acidic hydrogen of 4‐hydroxybutanenitrile
Identify the most acidic hydrogen atom in the compound below:
$$\ce{NC-CH2-CH2-CH2-OH}$$
My teacher said that the $\ce{H}$ connected to $\ce{O}$ is the most acidic since $\ce{O}$ is more ...
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0answers
65 views
Can I reverse an iron redox reaction with potassium hydroxide and electricity?
For a school project, about clean energy, me and my team are trying to build an iron battery. We are using a piece of iron (anode), potassium hydroxide (electrolyte), carbon electrode (cathode) ...
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2answers
102 views
Why doesn't ethanol dissolve in sodium bicarbonate?
Today I experimented with different solvents and solutes and was a bit surprised by one result. When I added ethanol to dilute sodium bicarbonate and tapped the test tube against my palm to mix it, I ...
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1answer
23 views
Using a weak acid to prevent the precipitation of Mg(OH)2
I have this exercise in my chemistry book, and I have been staring at it for so long but unfortunately I have no single idea what to do and where to start. I will be so thankful for any help.
$0.05$ ...
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0answers
30 views
Why is BF3 hard while BBr3 is borderline(HSAB concept)?
This is a table given in a text book regarding hard acids
How come BF3 is a harder acid than BBr3?
My reasoning: To check which is harder:
1.Both difficult to polarize
2.Both similar in size
It ...
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0answers
77 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
79 views
Acetone basicity [closed]
Why doesn't acetone have high basicity?
The C−O bond is polar, O becomes partially negatively charged and it should attract protons, becoming a strong base.
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0answers
27 views
What will be the Lewis acid and Lewis base in the reactions between aluminium(III) aqua complex and hydroxide?
$\ce{Al^3+}$ in water will be hydrated, formed a complex ion $\ce{[Al(H2O)6]^3+(aq)}$ that can neutralize hydroxide ion according to the following reactions:
$$
\begin{align}
\ce{[Al(H2O)6]^3+ + ...
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1answer
151 views
How do I calculate the ensemble-average net charge of an amino acid at given pH?
I am given an amino acid with an ionizable side chain at a certain pH. How do I determine the net charge of that amino acid when there are mixed protonation states of one or more of the groups at that ...
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1answer
22 views
Can I use Ascorbic acid powder as a preservative to extend the shelf life in pickled brine recipe? [closed]
Can I use Ascorbic acid powder as a preservative to extend the shelf life in pickled brine recipe made with vinegar?
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1answer
64 views
Neutralization between Ca(OH)2 + H2SO4 in a 30% hydrogen peroxide solution
I have performed an experiment where I added an excess of $\ce{Ca(OH)2}$ base to a solution consisting of 5 mL of 30 % hydrogen peroxide (buffered at pH 5) and a very small amount of sulfuric acid (...
1
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2answers
109 views
Why exactly is a fluoride anion a stronger base than iodine anion? [closed]
First off, I've learnt that stronger acids produce weaker conjugate bases (through Brønsted–Lowry acid–base theory).
Then I looked at the $\mathrm{p}K_\mathrm{a}$ values of $\ce{HF}$, $\ce{HCl}$, $\...
3
votes
2answers
30 views
Can mechanical agitation increase the reaction rate?
The specific example I saw recently was cleansing of concrete (portland cement) film from brick using a diluted muriatic acid. It appeared that the more scrubbing was used, the quicker the cleaning ...
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0answers
30 views
Will Chlorodifluoromethane (R22 refrigerant) react with calcium metal?
I am attempting to recycle or find a use for chlorodifluoromethane, however I do not want to risk venting it into the atmosphere or exposing myself to hydrofluoric acid. Ideally, I would like to ...
3
votes
1answer
74 views
Thermodynamic vs kinetic basicity [closed]
I'm writing something related to basicity and came across few papers that distinguish thermodynamic and kinetic basicity.
"In particular, the study of hydrogen bonding (H-bonding) within proton ...
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1answer
59 views
Calcium carbonate and hydrochloric acid - data analysis [closed]
I conducted an experiment in which $\pu{10mL}$ of dilute hydrochloric acid was added to a beaker, and this acid was heated up to room temperature ($\pu{22 ^\circ C}$) using a Bunsen burner. Then, $\pu{...
1
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1answer
47 views
Why is trichloromethane more acidic than trifluoromethane? [duplicate]
In Concise Inorganic Chemistry by JD Lee (4th edition; adapted by Sudarshan Guha), page 78 under the topic "Back Bonding" it is given:
$\ce{CHCl3}$ is more acidic than $\ce{CHF3}$ which is ...
1
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0answers
13 views
Is coupling reaction performed in acidic or basic medium? [duplicate]
Why is coupling reaction between aryldiazonium chloride and aniline carried out in a mild basic medium and not under acidic medium?
According to me, it can be performed in both mediums.
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Diketone intramolecular reaction question
I realize that one of the methyl groups on either carbonyl compound will become deprotonated and then it will attack the other carbonyl to form a pentane ring. However, with the methyl group in the ...
