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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).

4
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3answers
316 views

If change in free energy (G) is positive, how do those reactions still occur?

I was doing a couple of problems for homework: Calculate $K_\mathrm{sp}$ of $\ce{AgI}$ at $55.0\ \mathrm{^\circ C}$ Calculate $K_\mathrm{b}$ of $\ce{NH3}$ at $36.0\ \mathrm{^\circ C}$ I have to use ...
2
votes
1answer
41 views

Neutralisation Reaction Confusion

What will happen when $\pu{1 mol}$ of $\ce{H2SO4}$ reacts with $\pu{1 mol}$ of $\ce{NaOH}$? Will $\pu{1 mol}$ each of $\ce{NaHSO4}$ and water be formed? Or will $\pu{0.5 mol}$ of $\ce{H2SO4}$ will ...
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votes
2answers
69 views

pH of strong acid weak acid mixture [closed]

Question: $\ce{H2S}$ ($\pu{0.1M}$; $K_\mathrm{a} = 1.2×10^{-20} $) and $\ce{HCl}$ ($\pu{0.3M}$) with same volume are mixed together. What is the resultant $\mathrm{pH}$? My approach: Let the volume ...
2
votes
0answers
48 views

Common ion effect

Let $\ce{HA}$ ($x$ molar) be a strong electrolyte and $\ce{HB}$ ($c$ molar) — weak electrolyte. As $\ce{HA}$ is strong electrolyte, it dissociates completely: $$ \begin{array}{lcc} \ce{&HA &-&...
2
votes
0answers
42 views

Amount of benzoic acid required to alter pH of a NaOH-solution

I am trying to do a practice problem but I can't figure it out: How many grams of benzoic acid needs to be added to 0.10 l of a NaOH-solution with a concentration of 1.0 mM to reduce the pH of said ...
4
votes
0answers
42 views

Solubility of PbSO4

The solubility of $\ce{PbSO4(s)}$ increase with the addition of $\ce{H2SO4}.$ Why? I don't quite understand this. When dissolving $\ce{PbSO4(s)}$ we get the equilibrium equation: $$\ce{PbSO4(s) <=...
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votes
1answer
46 views

Methyl Orange Indicator-Reason for small amount of NaOH [closed]

I used methyl orange as my indicator to titrate a weak acid: At first, I added 3 drops of methyl orange to a solution of the weak acid, $\ce{CH3COOH}$, and the solution turned red. Then, after ...
2
votes
1answer
41 views

Calculating molecular weight of an acid based on given values of mass, volume, pH and pKa

This is what I thought was an easy problem but according to a given answer I am doing it wrong: $\pu{11 mg}$ of a monoprotic acid was dissolved in $\pu{0.5 l}$ of water. The resulting $\mathrm{pH}$ ...
-1
votes
1answer
45 views

Identifying weaker base

Can you tell me the reason behind the answer to this: Which is the weaker base? (a) o-cresol; (b) Trifluoro-o-cresol. Answer: (b) trifluoro-o-cresol. I'm not a student in any institution. So ...
0
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0answers
62 views

Resonance forms of deprotonated hydroquinone

What resonance forms stabilize deprotonated hydroquinone? Deprotonated hydroquinone looks like this: Possible resonance forms include: 1 and 2 look reasonable: they don't carry multiple charges. My ...
1
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0answers
32 views

What acids will Sodium Lauroyl Methyl Isethionate yield after hydrolysis? [closed]

As far as I understand, after hydrolysis Sodium Lauroyl Methyl Isethionate will yield sodium, lauroyl and methyl alcohols, and isethionic acid. Meaning lauroyl is referring to the fatty acid alcohol ...
0
votes
1answer
72 views

Basic strength of nitrogen

What is the order of basic strength of nitrogens in the compound given in the figure? $$\ce{ H2\overset{.\!\!.}{\underset{(γ)}{N}}-\overset{.\!\!.}{\underset{(β)}{N}}H-\overset{\overset{\huge O}{||}}{...
23
votes
1answer
3k views

Why does lemon juice reduce the “fish” odor of sea food — specifically fish?

In studying about amines, I read that lemon juice is also used to wash fish because it reacts with the amines on and in the fish to convert the amines to its salt, just reducing the "fishy smell". I ...
1
vote
0answers
27 views

Electron-donating trends for ligands bound to metal complexes

Imagine an inorganic complex with a bunch of terminal ligands. All else the same, would $\ce{F-}$ or $\ce{Br-}$ ligands be more electron-donating and why? Of course, in terms of $\mathrm{p}K_{\mathrm{...
7
votes
1answer
240 views

Is calcium chloride an acidic or basic salt?

What I reason: Calcium chloride is the salt of hydrochloric acid and calcium hydroxide. Calcium hydroxide is usually not considered a strong base, and I believe this is because of it's low solubility. ...
1
vote
1answer
114 views

Why do weak acids like ethanol not act as a strong base in water?

In water, ethanol has a $\mathrm{p}K_\mathrm{a} = 15.9$ which means that its $\mathrm{p}K_\mathrm{b}$ is $-1.9$. Which implies that all weak acids in water are in fact strong bases. But this is not ...
1
vote
1answer
66 views

What are the enthalpy and entropy contributions to carboxylic acids dissociating in water?

Carboxylic acids such as acetic acid do not dissociate much in the gas phase. In aqueous solution, however, they act as acids (proton donors). $$\ce{CH3COOH(aq) <=> H+(aq) + CH3COO-(aq)}$$ ...
0
votes
0answers
51 views

Sodium bicarbonate, varying acetic acid, measuring carbon dioxide volume, understanding results

With my 6yo daughter, I have conducted a simple experiment. We used 1/4 tsp (we don't have sub-gram scales) of bicarbonate of soda for each test. In each test, we used a different amount of vinegar (5%...
1
vote
1answer
76 views

What will be the order of acidity in the following compounds? [closed]

What will be the order of acidity in the following compounds ? From My point of view it should be 3>1>2>4. But the answer given is 3>2>1>4. Can anyone explain how ?
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0answers
24 views

H-bonding in o-hydroxybenzoic acid [duplicate]

Amongst all hydroxybenzoic acids the ortho isomer is most acidic and the major reason is intramolecular H-bonding in the anion. My question is that isn't the loss of proton destabilising the molecule ...
1
vote
1answer
28 views

pKa and equivalence point [closed]

I was doing a titration and using $\ce{NaOH}$ as the titrant. The analyte was a weak acid with a $\mathrm{p}K_\mathrm{a}$ of 4.90. Today I want to use another acid with a $\mathrm{p}K_\mathrm{a}$ of 4....
4
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0answers
40 views

Basicity af N containing aromatic species

Hello friends, I got struck in this interesting question on basicity. I am able to get different answers applying different methods. In general, for these compounds we have to see the lone pair ...
0
votes
0answers
46 views

Calculating pH of solution

What is the $\mathrm{pH}$ when you dissolve equal amounts of $\ce{NaHCO3}$ and $\ce{Na2CO3}$ in water? When both of the compounds are dissolved, we will have equal amounts of $\ce{HCO3-}$ and $\ce{...
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votes
1answer
62 views

Reaction of HF in water [closed]

I was wondering, if we put $\ce{HF}$ into a glass of water the acid will be dissolved according to this reaction: $$\ce{HF->F- + H+}$$ Now there is a proton travelling across the water. All $\ce{...
1
vote
1answer
37 views

Calculating pH of weak base and strong acid: Why is K(a) not required?

Question: 35mL of 1.5M $\ce{HCN}$, a weak acid(K(a)= $6.2*10^{-10}$) is mixed with 25mL of 2.5M $\ce{KOH}$. Calculate the pH of final solution. The solution given in my textbook is as follows:- $\ce{...
1
vote
1answer
33 views

Could this solution be resolved by titration?

I have a mixture of $\ce{NH_4NO_3}$ and $\ce{NH_3}$ at $\ce{pH}$ of about 13. It is possible to determine the concentration of both on them by acid-base titration? I was told it's possible, and that ...
5
votes
0answers
41 views

Why does my rainwater turn yellow if I increase the pH to 7?

My rainwater is colourless when collected, but if I add a small amount of sodium hydroxide to increase the pH to about 7, after a few days it goes yellow. The colour change happens more quickly if I ...
0
votes
1answer
28 views

Adjustment of calcium, magnesium and alkalinity in drinking water?

It's been a long time since I did any molar chemistry in school and despite doing a lot of reading on the subject this week, I am making a mess of some basic calculations. I hope that someone who ...
0
votes
1answer
29 views

pKa value of an indicator

Can we deduce the actual value of $\mathrm{p}K_\mathrm{a}$ of an indicator if the $\mathrm{pH}$ range has been given? I know that $\mathrm{pH}$ range is physically the range of values over which an ...
1
vote
1answer
59 views

Why do Hydrogen Halides(with the exception of HF) form mostly strong acids? [duplicate]

Why do Hydrogen Halides(with the exception of HF) form mostly strong acids? My guess is that the negatively charged Halide part of the molecule is attracted by the partially positive part of the water ...
2
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0answers
34 views

Protonation of pyridine

Recently, I have been reading the Nobel Lecture given by Kenichi Fukui when he won the Nobel Prize in 1981, for his contributions to the development of Frontier Molecular Orbital Theory. One of the ...
1
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0answers
22 views

Does the word HA always refer to a weak acid?

I was wondering if HA always represents a weak acid or can it also represent strong acids. Thank you all in advance
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2answers
46 views

Relationship between Ka and Kb

Considering the $K_\text{a}$ of the weak acid and the $K_\text{b}$ of the weak base that form the salt, we conclude that the solution will be acidic if $K_\text{b}$ > $K_\text{a}$ and basic if $K_\...
2
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2answers
64 views

Can I use the Henderson–Hasselbalch for calculating the pH of non-buffer systems?

Can I use the Henderson–Hasselbalch equation on reactions that are not buffers? When I read up on the derivation of the equation, I noticed that there is absolutely no assumption on the relative ...
4
votes
1answer
57 views

Is there any diprotoic acid where both pka's are less than 0?

The question states it all. I'm working out special cases for a different problem and such an acid would create another special case. Sulfuric Acid is the strongest that I remember. pKa's −3, 1.99
2
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1answer
39 views

Does hydrochloric acid change in concentration over time?

I have new bottles of 1 N hydrochloric acid from Fisher. The acid comes standardized from the company: Standardized at 25 °C to pH 8.2 against sodium hydroxide that has been standardized against ...
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votes
1answer
35 views

Which combinations can form buffer solutions? [closed]

I have a simple questions that I can´t solve . The answer is B though I really dont understand why since all of them have weak acid and a strong base
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0answers
38 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 other place it is written that it is there to protonate the hydroxyl group which fact should I believe ?
3
votes
1answer
400 views

When to use 1/Ka vs Kb [closed]

I'm really unsure what the difference is. We're using these when calculating $K$ of combined reactions. In general, I am also confused what $K$ is in comparison to $K_\mathrm{a}$ and $K_\mathrm{b}$. ...
6
votes
1answer
182 views

How accurately does (pKa1 + pKa2) / 2 estimate the pH of an amphoteric salt?

This question came up when answering Find the pH and amphiprotic salt is added to water at room temperature. If we dissolve $\ce{NaHA}$ in water, the species $\ce{HA-}$ can act as acid or base: $$ \...
2
votes
2answers
89 views

Find the pH of an amphiprotic salt dissolved in water at room temperature

Let's say I have a polyprotic acid $\ce{H2A}$ with the following properties: $$ \begin{align} \ce{H2A &<=> HA- + H+} & K_1 &= 1\cdot 10^{-1}\\ \ce{HA- &<=> A^2-+ H+} & ...
5
votes
3answers
572 views

Can solid acids and bases have pH values? If not, how are they classified as acids or bases?

This answer states $\mathrm{pH}$ is the aqueous concentration of $\ce{H3O+}$ or $\ce{H+}$ ions in soution. I would not say that ice lacks $\ce{H3O+}$ and $\ce{OH-}$ ions as ice's structure would ...
2
votes
1answer
33 views

At what acid concentration does potassium metabisulfite react?

I'm in the process of developing a well preserved food-stuff containing potassium metabisulfite and a number of acids (acetic, ascorbic, malic, tartaric, citric, lactic). Wine-making literature ...
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0answers
54 views

Trichloroacetic acid aqueous solution

I have bought some anhydride of trichloroacetic acid (TCA) and would like to prepare an acidic solution. My problem is, that I don't know how much "powder" to mix with how much water to produce an x% ...
1
vote
1answer
117 views

pH of CH3COOH + HCl solution (shouldn't be a buffer)

$\pu{0.05 L}$ of a solution containing $\pu{0.3 M}$ acetic acid $(\ce{CH3COOH}$, $K_\mathrm{a} = \pu{1.8e-5})$ are added to $\pu{75 mL}$ of a solution containing $\pu{0.02 M}$ hydrochloric acid ($\ce{...
0
votes
1answer
109 views

What is double titration?

I an currently studying acid-base titrations. There is a concept of double titration. Can someone provide me an idea on what actually it is? Also what resources can I refer to?
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1answer
124 views

Can neutralization ever be complete?

Suppose we have 1 eq of acetic acid and we want neutralize it using sodium hydroxide. After adding 1 eq of sodium hydroxide 1 eq of sodium acetate should form and neutralization should be complete but ...
3
votes
6answers
222 views

How to calculate pH of basic salt solution mixed with strong base?

Calculate $\mathrm{ pH }$ of $\pu{ 0.05 mol }$ of $\ce{Zn(CH3COO)2}$ and $\pu{ 0.025 mol }$ of $\ce{ NaOH }$ dissolved in $\pu{ 1 L }$ of distilled water? I tried to use the systematic method by ...
0
votes
0answers
21 views

Calcium Phosphate Bridges in Casein Micelles being dissolved using Ethanoic Acid

I am writing a chemistry essay about casein isolation using acid precipitation. I read that the casein micelle itself is constructed of more "mini" micelles, which are constructed of the constituents ...
1
vote
2answers
98 views

How can we tell if an ion is amphiprotic [closed]

If I had the following ions: $$\ce{HCO3^-}$$ $$\ce{H2PO4^-}$$ $$\ce{CH3COO^-}$$ Which ones would be amphiprotic? Looking at my $ K_A$ chart, it looks like each ion is formed by the disassociation of ...