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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4
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2answers
3k views

Why is water ignored in the ionic equilibrium of HF?

While trying to understand the solution of a problem given in my textbook, I realized I'm having some difficulty with the solution. The problem is as follows: The ionization constant of $\ce{HF}$ ...
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3answers
470 views

Am I understanding buffering capacity against strong acid/base correctly?

I just want to make sure I'm understanding buffering capacity correctly. I've been working on this problem: Suppose you have an acetic acid buffer, $\mathrm{p}K_\mathrm{a} = 4.74$, at the ...
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3answers
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Why oxides with the element in higher oxidation state are more acidic

We see this trend of acidic-basic property of oxides in most cases: $\ce{Mn2O7}$ is acidic, $\ce{MnO}$ is basic, the intermediate oxides are progressively less acidic and more basic, as the oxidation ...
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1answer
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Which proton is more acidic in this compound?

I'm having trouble determining which of these protons is more acidic. I was thinking the solution had something to do with the double bond in the aromatic ring, but I'm still not sure.
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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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2answers
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What are the crystals that have formed around the top of a conc. nitric acid bottle?

I was looking through my chemicals cupboard and found that this decades-old bottle of conc nitric acid had grown a beard. I can't think of any reaction between (presumably) $\ce{NO2}$ and any airborne ...
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1answer
280 views

Steric Inhibition of Resonance in ortho-substituted Benzoic Acids

It is given that due to Steric Inhibition of Resonance (SIR), the acidity of ortho-substituted benzoic acid increases with respect to benzoic acid. However, I'm unable to understand the reason behind ...
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0answers
29 views

How do you find the ph of lime juice through titration?

I am doing an experiment on the effect of time on the pH of Lime juice. I was wondering how you would calculate the pH through titrations using 1 Molar NaOH. I have been racking my brain on this for a ...
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0answers
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Trends in the acid strength of oxoacids

I was working on a problem regarding the relative acidity of oxoacids in the form $\ce{HYO3}$ where $\ce{Y}$ represents a group 17 element. The question (which is from a worksheet created by a ...
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2answers
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Acidity of cyclopentadiene when fused to benzene rings

Why does fusion to a benzene ring reduce the acidity of a cyclopentadiene ring? For example, acidity decreases going from cyclopenta-1,3-diene to indene and to fluorene:
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2answers
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Why does having equivalent resonance structures give more stability?

Although the phenolate ion has more resonance structures (4) compared to acetate ion (2), acetate is more stable because it has two equivalent resonance structures of same energy. Why does having ...
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2answers
94 views

Why is H⁺ ion considered the source of acidity, and OH⁻ considered the source of basicity? [closed]

As the title implies, what caused the association between $\ce{H+}$ and acidity, and between $\ce{OH-}$ and basicity?
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2answers
311 views

What is the reaction equation for a mixture of trichloroethanoic acid and dimethylpropanoic acid?

Write an equation for the reaction you might expect to take place if trichloroethanoic acid, $\ce{Cl3CCO2H}$, $\mathrm{p}K_\mathrm{a} = 0.65$, were added to dimethylpropanoic acid, $\ce{(CH3)3CCO2H}$, ...
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2answers
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How are CH3COOH molecules ionisied into H+ and CH3OO- [closed]

It's written in my chemistry book ,under weak acids, that the molecules of organic acids are partially ionised in water into ions. But I don't understand how molecules are ionised. I'm an ol ...
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2answers
480 views

Can we use (KBr + H2SO4) instead of (NaBr +H2SO4) in reaction with alcohol to generate alkyl bromide?

I have read somewhere that $\ce{H2SO4}$ is used to generate $\ce{HBr},$ and at the other place it is written that it is there to protonate the hydroxyl group. Which fact should I believe ?
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1answer
510 views

Back titration of excess HCl used for dissolving limestone

$15.0~\mathrm{mL}$ of $1.4~\mathrm{M}\ \ce{HCl}$ was mixed with $1.00~\mathrm{g}$ of limestone (impure $\ce{CaCO3}$) until all the solid had dissolved. The solution was then transferred to a conical ...
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2answers
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How can I eliminate the harmful gas produced from the heating/manipulation of galvanized steel? [closed]

When welding on steel with a galvanized coating, hexavalent chromium is yielded from the chemical reaction. This gas is something that I would like to eliminate before I begin welding, possibly with ...
5
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1answer
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Why is tetramethylammonium hydroxide a stronger base than tri- or dimethyl amine?

Of the following, which compound is the most basic?? $\ce{Me3N}$ $\ce{Me2NH}$ $\ce{Me4NOH}$ $\ce{NaOH}$ Between 1 and 2, 1 is more basic as the 3 methyl groups would produce a +I ...
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2answers
114 views

Strength of bases and acids

Is it possible that strong acids like $\ce{H2SO4}$ behave as weaker ones like $\ce{CH3COOH}$ when the concentration is really high and vice versa for weak acid? And the same question for bases. By ...
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3answers
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Why is HCl a stronger acid than Acetic Acid?

Drawing the conjugate bases, Oxygen is more electronegative than Chlorine so negative charge on Oxygen is more stable than Chlorine, Thus My argument that Acetic Acid is more acidic. Also the O¯ ...
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0answers
69 views

Can Acids have pH of more than 7? [duplicate]

Consider a solution of $\text{HCl}$ with a concentration of $10^{-10}$ $\text{M}$. Now, if I find it's pH: $$\begin{aligned}\text{pH} &= -\log([\text{H}^+])\\ \text{pH} &= -\log(10^{-10}) = 10\...
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1answer
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How to tell if an acid disassociate completely or partially? [closed]

what is the difference between and how can I tell which one is the stronger acid, base on the 2 equations?
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1answer
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Why does Calcium (specifically Calcium Carbonate) inhibit the Citrate buffer system?

Is it because citrate chelates calcium and then is unable to react with other chemicals being added? If so can someone explain this reaction to me, or if not provide what the reason is? If anyone has ...
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1answer
57 views

What happens to concrete if you add lye to the mix?

What happens if you’re mixing concrete and you add some lye to it? Does it make it weaker, stronger or does nothing at all? I’m guessing concrete is basic so adding lye to it might expedite the ...
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1answer
72 views

Accurate method to calculate the pH of a salt from a weak acid and weak base

Can someone help me with this? The problem is as follows: Find the $\mathrm{pH}$ of $\pu{1M}$ solution of $\ce{NH4CN}$. Their respective hydrolysis constants are: $K_h = 5.6\times 10^{-10}$ ...
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0answers
54 views

Why H3PO2 does not form acid salt? [closed]

Why $\ce{H3PO2}$ does not form an acid salt? I didn't understand the language.
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1answer
753 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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1answer
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Which is more basic among N-ethylpiperidin and 1-azabicyclooctane?

Shouldn't A be more basic than A because in B the conjugate base formed in B is more unstable as compared to A and because a bridge head nitrogen is formed In B which is comparatively unstable than ...
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3answers
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Reaction of concentrated nitric acid react with metallic lead?

Here is my work: Concentrated $\ce{HNO3}$ should first decompose into $\ce{NO2}$, $\ce{H2O}$ and $\ce{[O]}$. Nascent oxygen should combine with $\ce{Pb}$ to form $\ce{PbO}$. Now $\ce{PbO}$ should ...
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1answer
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Order of lewis basic strength

My teacher told me that order of lewis basic strength is inversely proportional to electro negativity. Comparing between iodide ion and chloride ion, chloride ion is more electronegative than iodide ...
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1answer
137 views

How sure can we be about the structure of purine?

While answering the question Basicities of nitrogen atoms in purine, I noticed, that there might be a rapid interchange of the hydrogen bonded to the nitrogen atoms. I have found a crystal structure ...
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4answers
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Is sulfide ion a stronger base than hydroxide ion?

I received these three responses. They are all, except the last response, incorrect to varying degrees. I am, however, unsure about how to grade these responses because the question itself, in my ...
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0answers
29 views

Reference for Hammett acidities of dilute H2SO4?

When $\ce{H2SO4}$ is dissolved in water in little amounts ($<\pu{1M}$), the $\mathrm{pH}$ scale can be used to measure the acidity of the solution. However, in larger concentrations, this breaks ...
6
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1answer
74 views

No phenolphthalein mono-anion?

This is a follow-up to the question here. There is no mono-anionic stage shown, does it "disproportionate" to the neutral molecule and the di-anion?
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2answers
285 views

Deprotonated form of phenolphthalein

The wikipedia page states clearly that the coloured form of phenolphthalein is the one with two protons removed. What is the evidence that phenolphthalein loses both protons in basic solution? And ...
0
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1answer
54 views

Contradictions in acidity and solubility of phenol derivatives

o-Nitrophenol is less acidic in comparison to p-nitrophenol due to intramolecular hydrogen bonding. This effect also is the reason for o-nitrophenol being less soluble in water. At the same time, ...
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1answer
52 views

Estimation of Sodium Hydroxide

Why is estimation of sodium hydroxide more accurate with oxalic acid rather than with sulfuric acid or any other strong acid?
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0answers
19 views

How are the pKa's of very strong acids derived mathematically?

It is often said that "for very strong acids (HCl, H2SO4, etc.), the pKa value cannot be experimentally derived from standard titration and instead needs to be theoretically computed". However, I ...
1
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1answer
195 views

Do amphoteric cations exist?

I know that anions such as $\ce{CH3COO-}, \ce{OH-}, \ce{CN-}$ are basic in nature, since they are conjugate bases of weak acids. Similarly, cations such as $\ce{NH4+}, \ce{H3O+}$ are acidic in nature ,...
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0answers
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How ion size/electronegativity influences strength of an acid

My prof was explaining how we can use the structure of acids and bases to rationalize relative strengths (ie: acid X is stronger than acid Y because ...). He then went on to explain how when ...
3
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1answer
2k 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?...
0
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1answer
99 views

Validity of the leveling effect of water in nitration reactions

Wikipedia gives this as the levelling effect of water Any acid that is stronger than $\ce{H3O+}$ reacts with $\ce{H2O}$ to form $\ce{H3O+}$. Therefore, no acid stronger than $\ce{H3O+}$ exists in $\...
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0answers
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What exactly is going on in this reaction: sodium bicarbonate (supersaturated aqueous), isopropyl alcohol, and acetic acid (vinegar)?

I had observed this reaction by playing around with vinegar and baking soda and do not completely understand it. Everyone knows that baking soda and vinegar goes crazy and starts creating carbonic ...
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1answer
139 views

Lewis acidity comparison of boron and aluminium trichlorides

Lewis acidity is a function of electron deficiency on the acceptor atom, which in this case is $\ce{B}$ and $\ce{Al}$ respectively. Back donation is better as is the case of $\ce{B}$, due to better ...
13
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1answer
5k views

Is the equation pH + pOH = 14 valid at different temperatures?

$\mathrm{pH} + \mathrm{pOH} = 14$ For water at 60 degrees Celsius, $K_\mathrm{w} = 1 \times 10^{-13} = [\ce{H+}] \times [\ce{OH-}]$ Hence, $[\ce{H+}] = 1 \times 10^{-6.5} = [\ce{OH-}]$ So $\...
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2answers
808 views

Which one is the strongest base among the following compounds?

I am confused between option (2) and (4). Both lone pairs of nitrogen are localized, so next, I looked at the hybridization of $\ce{N}$ in each compound. As in (2), the $\ce{N}$ is $\mathrm{sp^2}$ ...
0
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1answer
3k views

In antacids like Eno that fizz up when mixed in water, why is the citric acid important?

I know that you can get rid of the acidity if you just take some baking soda added in water. I learned that these antacids that fizz up also have some citric acid and they react when added in water ...
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3answers
3k views

Why is RS- more basic than RO-?

The basic strength is determined by the ability of an ion or molecule to accept a proton. How do I know whether RSH is more stable than ROH? (R is an alkyl group)
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2answers
355 views

Determining Acidity in organic compounds [closed]

Among the following compounds,the strongest acid is: (a) $\ce{C2H2}$ (b) $\ce{C6H6}$ (c) $\ce{C2H6}$ (d) $\ce{CH3OH}$ My doubt is how do we see acidity in such cases.....arhenius or lewis definition ...
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1answer
4k views

Neutralizing a sulfuric acid spill

From my AP Chem Prep Book: What should you do if you spill sulfuric acid on the countertop? A) Neutralize the acid with vinegar. B) Sprinkle solid NaOH on the spill. C) Neutralize the acid ...

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