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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2
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2answers
83 views

Low-cost nontoxic corrosion inhibitor for steel exposed to hydrochloric acid

It seems that many commercial descaling solutions designed to remove scale (calcium carbonates, etc that form on water heaters) are a simple combination of an acid and an acid corrosion inhibitor for ...
41
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4answers
6k views

What is more acidic: D3O+ in D2O or H3O+ in H2O and why?

What is more acidic: $\ce{D3O+}$ in $\ce{D2O}$ or $\ce{H3O+}$ in $\ce{H2O}$ and why? I think it's $\ce{D3O+}$ in $\ce{D2O}$ as I saw somewhere that this property is used in mechanistic studies (...
2
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1answer
81 views

Why does pH of a buffer solution change according to Henderson–Hasselbalch equation? [closed]

If I add a little amount of acid or base to a buffer solution, the pH of the buffer won't change. That's what the diagramatic mechanism tells us. But according to Henderson–Hasselbalch equation, the $...
1
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1answer
67 views

Can antimony pentafluoride be made by adding hydrogen fluoride to antimony trifluoride?

I was looking at how the strongest acid was made and I found something I did not understand. On the Wikipedia page for antimony trifluoride it shows the production of $\ce{SbF3}$ using $\ce{HF}$: $$\...
2
votes
1answer
36 views

Evaluate indicator choice (phenolphthalein)

A student wishes to find the concentration of a $\pu{50 mL}$ solution of acetic acid $(K_\mathrm{a} = \pu{1.8e-5}).$ He performs a titration using a solution of $\pu{0.2 M}$ sodium hydroxide. The ...
1
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1answer
42 views

What makes a compound basic? [closed]

Aluminum chlorohydrate is often referred to as basic aluminum chloride. The pH value of ACH is about 4. How is basicity in this context defined?
33
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9answers
9k views

Would it be possible to destroy gold?

I'm a writer. I have a scenario in which a sizable amount of gold needs to be rendered unusable, preferably completely destroyed. I know an acid like aqua regia is able to dissolve gold, but would ...
1
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1answer
40 views

is every molecule either a base or acid

I read today that water is a base because it can receive a proton when mixed with some acids. That got me thinking: is every single molecule capable of either donating or receiving a proton -- when ...
1
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0answers
11 views

How do I go about either finding or calculating Aluminum-Oxalate salt solubility values in aqueous medium?

Water would contain other salts which may complicate things a bit. But finding out the Aluminum-Oxalate salts solubility values in pure water would be a good indicator already. It's for temperatures ...
13
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2answers
2k views

How to remove stain from pavement after having dropped sulfuric acid on it?

I had this car battery that flipped in my car trunk. When I got it out of there it spilled some acid on the pavement. It's a sulfuric acid battery. I added some baking soda on it and poured some more ...
1
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0answers
119 views

Polar Protic and Aprotic Solvents

I know $\mathrm{S_N2}$ is favored polar aprotic solvents, which means that they may have hydrogens on them somewhere, but they lack $\ce{O-H}$ or $\ce{N-H}$ bonds, and therefore cannot hydrogen bond ...
-1
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1answer
179 views

Order of acidic strength of oxides

Select the correct order of acidic strength of oxides: (A) $\ce{SO2} > \ce{SO3} > \ce{CO2}$ (B) $\ce{Cs2O} > \ce{K2O} > \ce{Na2O}$ (C) $\ce{CO2} > \ce{N2O5} >\ce{B2O3}$...
0
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2answers
88 views

How do we know if a compound is amphoteric or not?

My teacher told me if it reacts with an acid and a base, then the compound is amphoteric. However, I am not satisfied. Is there any other way of telling? For example we are give a compound say BeO, ...
0
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1answer
84 views

Kb values of N,N-dimethylaniline derivatives [closed]

I need the $K_\mathrm{b}$ values for ortho-, meta- and para- positions of the following compounds: I've looked and couldn't find them anywhere.
6
votes
2answers
252 views

How are neutral amines effective bases in organic chemistry?

I have found it to be rather strange that neutral amines, such as triethylamine or DIPEA, find applications in organic chemistry in deprotonating alcohols or even α-carbonyl compounds. Amines are ...
1
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0answers
28 views

Acid and base separation on an anion exchange column [closed]

I'm new with this concept and so I would need some advice. I want to separate an acid and a base in a water solution. The acid has $\mathrm{p}K_\mathrm{a}(\ce{HA}) = 5$ and the corresponding acid of ...
2
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0answers
43 views

Hydrolysis of an amidine derivative under acidic conditions

I know that an imine can undergo acid hydrolysis to yield a corresponding amide: https://chem.libretexts.org/@api/deki/files/13283/10.jpg?revision=1 But I am looking at a mechanism for acid ...
1
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2answers
497 views

NaHCO3 required to raise pH of weak HCl solution from 3.5 to 7.2 (doubting my calculations)

I'm a dentist, working on a medical device that will make shots at the dentist office hurt a lot less. The device mixes a drug (2% Lidocaine) that has been acidified with $\ce{HCl}$ to pH 3.5 for ...
0
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0answers
70 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 ...
0
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0answers
56 views

Calculate the pH

Calculate the pH of a dissolution of 100 ml of 0.1 M solution of ammonium chloride in the style of 100 ml of 0.1 M hydrochloric acid solution $\ce{NH4Cl -> NH4+ + Cl-}$ $\ce{HCl -> H+ + Cl-}$ ...
12
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2answers
949 views

Why are synthetic pH indicators used over natural indicators?

Synthetic indicators seem to be exclusively used when determining the pH of a substance with an indicator (with the exception of that school experiment where you boil cabbage to demonstrate natural pH ...
-1
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2answers
47 views

Is this balanced redox equation correct? [closed]

I'm trying to balance an equation using oxidation numbers $\ce{MnO4^- + H+ + Cl- -> Mn^2+ + Cl2 + H2O}$ my suggestion: $\ce{MnO4- + 8H+ + 5Cl- → Mn^2+ + 2.5Cl2 + 4H2O}$ the 2.5 $\ce{Cl2}$ is ...
0
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1answer
57 views

What is the pH at both equivalence points of titration between diprotic tartaric acid and NaOH?

Here's all the info I have and my attempt in solving the question: The chemical equation for the titration: $$\ce{C4H4O6 + 2NaOH -> Na2C4H4O6 + 2H2O}$$ Here are the 1st and 2nd $\mathrm{Ka}$ ...
6
votes
3answers
40k views

How to rationalise that when we dilute a weak acid, the pH increases but also the dissociation increases?

When water is added to a weak acid like ethanoic acid, the number of ethanoic acid molecules that dissociate increases, however, pH increases (less acidic), too. Why is this so?
0
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1answer
22 views

How do I calculate the proportion of respective conjugates of one base mixed with several acids (and/or conversely) at different temperatures? [closed]

How do I calculate the proportion of respective conjugates of one base mixed with several acids (and/or conversely) at different temperatures, and is there a free software tool that would allow me to ...
0
votes
3answers
68 views

4-Bromophenol vs 4-aminophenol pKa in water comparison confusion

Recently the other week, I was asked the following question: Would you expect 4-aminophenol to have a higher or lower pKa than 4- bromophenol when measured in water? And I thought about this on ...
0
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1answer
72 views

Titration of aspirin

I have performed an experiment to test how temperature affects how fast aspirin dissolves by titrating solutions at various time intervals. According to this website, aspirin reacts with water as such:...
0
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2answers
588 views

Which of the following is the most acidic salt?

A 0.1 M solution of which salt is most acidic? (a) Aluminum(III) nitrate $\ce{Al(NO3)3}$; (b) Magnesium(II) bromide $\ce{MgBr2}$; (c) Sodium bicarbonate $\ce{NaHCO3}$; (d) Sodium formate $\...
1
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1answer
370 views

When calculating enthalpy changes of reaction using, why is only the amount of substance of one reactant used?

When calculating the thermal energy released during an acid-base neutralisation using the equation $Q = mc\,\Delta T$, and then using $\Delta H = - Q/n$ to calculate the enthalpy change of ...
1
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1answer
47 views

Changes over time in sodium hydroxide concentration in a hot water bath used for pretzel manufacture

I make soft pretzels using a hot (190 °F) and dilute (2-4% w/v) sodium hydroxide solution. The bath is kept hot in a open-top stainless steel vessel like a stockpot. I make my pretzel dough and dip ...
1
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1answer
111 views

Calculating pH when weak base is added to an strong acid

$\ce{NH3}$ solution of $\pu{0.1 mol dm-3}$ is being added to a $\pu{25.0 cm3}$ of $\pu{0.1 mol dm-3}$ $\ce{HCl}$ solution. Calculate the pH of the solution when volume of added $\ce{NH3}$ solution is $...
1
vote
1answer
130 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 ...
0
votes
1answer
50 views

What should be the molarity of HCl and H2SO4 acid so that they can be considered safe to touch? [closed]

I know $\ce{HCl}$ and $\ce{H2SO4}$ acid of concentration 17 M is dangerous and corrosive, but I wonder can we dilute these acids to the extent that they become safe to touch? If yes, then what should ...
0
votes
2answers
82 views

What atom would be protonated first in a strongly acidic solution?

The answer is A. I thought it would be D since the ester group has the highest pka and the more basic functional group would be more prone to protonation. Also, I don't really get how to rank C in ...
2
votes
1answer
67 views

Can I use litmus paper to test unknown liquid that contains a concentrated strong acid?

Can I use litmus paper to test unknown liquid that contains a concentrated strong acid (example $\ce{H2SO4}$)? Can concentrated strong acid destroy litmus paper?
1
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1answer
47 views

Will strong concentrated acid destroy litmus paper and pH paper if they are dipped in acid?

I am curious to know what will happen if I have litmus paper and pH paper, and I dip them into strong concentrated acid like conc. $\ce{H2SO4}$ to test its acidity or basicity. Will acid destroy ...
1
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2answers
25 views

Can a low concentration of an acid disolve solids just as well?

I'm in the process of removing some hard water stains with vinegar. It's not working so well. The stains are in a large fish tank, which I have filled with water and vinegar. I would expect a lower ...
-3
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2answers
2k views

How to write equations for a reaction of metals with water

Please write two equations for reacting lithium with water and barium with water. Make sure to add the states of matter after each compound. Currently, for lithium I have the equation $$\ce{2Li(s) +...
5
votes
1answer
171 views

Why is the dissociation reaction of acetic acid in water initially endothermic and then exothermic?

Why is the dissociation reaction of acetic acid in water initially endothermic as temperature is increased and then becomes exothermic as it is increased further? My understanding from Le Chatelier's ...
0
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1answer
38 views

Ammonium chloride in aqueous solution

When Ammonium chloride is in an aqueous medium its cation part ammonium undergo hydrolysis. Since ammonium is conjugate acid of a weak base it readily release one $\ce{H+}$ and converts back to $\ce{...
0
votes
1answer
55 views

How to find the strongest base using stability arguments

Answers: The most acidic is D and the most basic is A. So first off I compared A with B: I'm kinda confused on this. I looked at the base NH one and saw that when it was protonated it lost its ...
2
votes
2answers
91 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 ...
5
votes
2answers
2k views

pH of a buffer made with boric acid and potassium dihydrogen borate

The Problem Calculate the pH of a buffer that is $\pu{0.200M}$ $\ce{H3BO3}$ and $\pu{0.122M}$ $\ce{KH2BO3}$. The $K_\mathrm{a}$ for $\ce{H3BO3}$ is $7.3\times10^{-10}$ What I Tried For each of ...
5
votes
1answer
14k views

Litmus paper - turning red, blue and even bleached

I have blue litmus paper, and if I put it in an acid it turns red. I also have red litmus paper, and if I put it in a base, it turns blue. I know the question about litmus was asked and answered and I ...
1
vote
0answers
54 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: $$\text{pH} = -\log([\text{H}^+])$$ $$\text{pH} = -\log(10^{-10}) = 10$$ At room temperature, ...
2
votes
2answers
148 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+} & ...
36
votes
4answers
40k views

The reason behind the steep rise in pH in the acid base titration curve

Most books refer to a steep rise in pH when a titration reaches the equivalence point. However, I do not understand why … I mean I am adding the same drops of acid to the alkali but just as I near the ...
0
votes
0answers
81 views

Acidity order of carboxylic compounds [duplicate]

Arrange the following acids in decreasing order of acidity: (a) X > Z > Y (b) X > Y > Z (c) Z > X > Y (d) Z > Y > X I arrived at option (c) according to -I effect, but the answer ...
0
votes
3answers
1k views

Basicity of nitrogen heterocyclic compounds

Question : The order of basicity for the following compounds is : The logic I've applied is that since 4 has a conjugated system, the lone pair of N will be delocalised and hence would be the ...
5
votes
0answers
80 views

Why is there no effective alternative to metal salts in antiperspirants?

Metal salts, especially aluminum compounds are used in antiperspirants to prevent sweating. I found out aluminum chloride hexahydrate, which is found in most antiperspirants, undergoes an acid-base ...