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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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1answer
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How does monoethanolamine (MEA) increase pH?

I know pH of a solution increases with increase concentration of $\ce{OH-}$. I'm wondering: when adding MEA, is the $\ce{OH-}$ group from the MEA breaking off, or is it the whole MEA molecule taking ...
-3
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0answers
31 views

Hydrofluoric acid in the body causing a acidic blood [on hold]

Jet fuel splashed on person and hydrofluoric acid seeped in and targeted calcium in pelivis and feet. How would you treat it
4
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4answers
167 views

Why does the degree of dissociation change when we dilute a weak acid even though the equilibrium constant $K$ is constant?

$K$ represents the ratio of concentrations of molecules in a solution at equilibrium, which means that $Q_\mathrm{r}$ (that ratio at any given point) looks to be identical to $K$. In other words, the ...
3
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1answer
53 views

Comparison of acidities

My book says To compare the acidities of two compounds, compare the stability of the anions formed by loss of a proton with respect to the original compound. Suppose we have acetic acid and ethyl ...
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1answer
34 views

Identifying Lewis acid

What is the Lewis acid on the reactants side? $$\ce{HNO2(aq) + HPO4^{2-}(aq) <=> NO2-(aq) + H2PO4-(aq)}$$ The book says it is the $\ce{H+}$ only, not the whole molecule of the nitrous acid, ...
2
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1answer
33 views

Does hyperconjugation into sigma-star explain methylamine's increased basicity relative to ammonia?

The inductive effect with the polarisation of the C-N bond obviously plays a role in stabilising the positive charge of the conjugate acid. But given the similar electronegativities for C and H, CH3 ...
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0answers
41 views

When is an organic phosphate acid and when is it not? [on hold]

I would like to know when an organic phosphate is acid and when it is basic. I think I need the acidity constant given by the equilibrium equation in aqueous environment. I tried to find the ...
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0answers
35 views

Mass-Charge balance equations

How to write mass balance equations and charge balance equations of the solution composed of $\pu{0.1M}\text{ }\ce{ NaH2PO4}~ \text{and}~\pu{0.05M}\text{ }\ce{ Na2HPO4}$? After writing the equilibria ...
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0answers
20 views

How can I remove iron oxide from acidic solution? [on hold]

I do some experiment for chemical treatment on dyeing sludge with iron sulphate. This chemical removes dye with chelating with dye. pH of sludge is 12 and after treat with iron sulphate decrease till ...
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1answer
44 views

Titration of 0.2 M KOH with 0.05 M HCl [closed]

I need to use the following example to calculate the acid base reaction for the titration of $\pu{0.2 M}\; \ce{KOH}$ 0.2 N with $\pu{0.05 M}\; \ce{HCl}$ 0.05 N of a sample that produces $\ce{CO2}$. ...
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0answers
26 views

Solving Polyester but no chromed steel

In short I'm looking for an acid that can solve a polyester, fiberglass composite. However it cannot damage steel. First of all i like to say that i'm not a chemist. I work in a plastic moulding ...
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1answer
26 views

Polyprotic Acid Titrations

Titrating a mixture of strong and weak acids will yield endpoints such that the volume of base required to reach each endpoint will be different for each acid, e.g. in a mixture of HCl and CH3COOH, ...
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0answers
26 views

Does equilibrium shift (for an acid) mean enhancing its strength? [closed]

Consider the equilibrium reaction of Acetic Acid dissociating into Acetate anions and hydrogen ions. If NaOH is introduced into this system, there are 2 possibilities: 1) The NaOH can react with (...
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0answers
22 views

What are rules for determining pKb and basicity? [closed]

How to solve this $\mathrm{p}K_\mathrm{b}$ and basicity? Arrange the following: In decreasing order of the $\mathrm{p}K_\mathrm{b}$ values: $\ce{C2H5NH2}$, $\ce{C6H5NHCH3}$, $\ce{(C2H5)...
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0answers
24 views

Acid rain and the Carbon Dioxide in the atmosphere [closed]

How much $\ce{CO2}$ in the atmosphere has been caused by acid rain's effect on limestones and the like?
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0answers
31 views

Comparing acidity in 3,4-dihydroxyfuran-2(5H)-one and 2,3-dihydroxycyclopent-2-en-1-one

I have two compounds with two hydrogens namely (a),(b),(c) and (d). I have to compare the acidity of the following hydrogens. My approach: I removed the hydrogen atoms one by one and compared the ...
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2answers
58 views

Why can't a weaker acid protonate the conjugate base of a stronger acid?

So I've heard that, supposedly, a weaker acid cannot protonate the conjugate base of a stronger acid to give that stronger acid. For instance, adding ethanoic acid to sodium sulphate will not result ...
4
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0answers
32 views

Which one is the stronger Lewis base: diethyl ether or tetrahydrofuran?

I am trying to understand Lewis bases (bear with me, I am a physicist). I was asking myself how diethyl ether and tetrahydrofuran compare with respect to their properties as solvents in electrophilic ...
-2
votes
1answer
69 views

Q. 36 2018 molar solubility of CaF2 at pH3 given molar solubility at pH7 and pKa of HF [closed]

This is Q36 on the 2018 Chemistry Olympiad: Calcium fluoride, $\ce{CaF2}$, has a molar solubility of $\pu{2.1e–4 mol L–1}$ at pH = 7.00. By what factor does its molar solubility increase in a ...
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0answers
22 views

How can the ocean act as a buffer?

I was reading up on the buffering effect of the ocean and I was quite confused about how the buffer is able to do anything. The buffer I will refer to is below: $$\ce{CO3^{-2} +H2O <=> HCO3 + OH^...
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1answer
33 views

Lewis acid character

Which will have more lewis acid character out of $\ce{BCl3}$ and $\ce{AlCl3}$ ? My attempt: In $\ce{BCl3}$, the back bonding takes place and there is 3pπ-2pπ overlap and in $\ce{AlCl3}$ it is 3pπ-...
1
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1answer
34 views

Calculate pKa for lipids

I would like to calculate $\mathrm{p}K_\mathrm{a}$ of lipid molecules using some software tools. I have tried ChemAxon and compared with ChemDraw professional 16.0 version they are mostly similar. I ...
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0answers
19 views

Why do alkaline breads bake browner/crustier?

Usually, when I bake bread there is only one leavening agent (either yeast or baking soda). However, today I tried a new recipe for cinnamon rolls that used yeast but then called for the addition of ...
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2answers
73 views

Which one is more acidic – 3,5-dinitrophenol or 4-nitrophenol

I’m confused because in 3,5-dinitrophenol, the inductive effect is dominating whereas in 4-nitrophenol the mesomeric effect dominates. So which one should we consider for acidity?
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1answer
31 views

Error with explaination of shape of weak acid strong base titration?

I have read the other posts on the same question posted on chemistry exchange such as this one: Shape of Weak-Strong Acid-Base Titration and here : What does the small, steep curve at the very ...
5
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2answers
71 views

Should the tip of the burette of an automatic titrator be immersed in the analyte?

In all the tutorials I found online, the tip of the burette (containing the titrant - NaOH) was immersed into the analyte solution. My question is: shouldn't the tip be out of the solution? Isn't ...
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2answers
54 views

What are the concentration changes when diluting an equimolar acetic acid: acetate buffer?

When a buffer (for example, a mixture of 100 mM acetic acid and 100 mM acetate), is diluted 10-fold, all the concentrations change drastically. Surprisingly, after re-establishment of equilibrium, the ...
0
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1answer
45 views

Equilibrium constant for the neutralization of weak acid by strong base

Acetic acid has a $K_\mathrm{a}$ of $\pu{1.8e-5}$. What is the equilibrium constant for the neutralization of this acid with $\ce{NaOH}$? Given acetic acid $$\ce{HC2H3O2 + H2O <=> C2H3O2- + ...
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1answer
33 views

Ranking basicity from a structure

I just came across this question in my revision. I selected (A) but the correct answer is (D). Could someone explain where I am going wrong? I is least stable --> most reactive --> most basic Cl is ...
0
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1answer
83 views

How is preparing a buffer possible?

I understand the concept of an equilibrium buffer solution, however I am a bit hung on how creating it doesn't shift the weak acid equilibrium. $$\ce{CH3COOH + H2O <=> CH3COO- + H3O+}$$ $$ K_\...
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0answers
34 views

How is hexanamide more acidic than aniline?

To compare the acidic strength, we compare how stable the conjugate base is right? So both of the conjugate bases have a negative charge on nitrogen. And both show resonance stabilization. What I ...
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4answers
280 views

Structure of pyrophosphorous acid

What is the structure of pyrophosphorous acid? I asked this question here because the answer which I found on web and other resources are inconsistent which each other. For example, following data is ...
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1answer
78 views

Conflicting definitions of Lewis acids

I have struggled in attaining a solid grasp of the Lewis acid/base concept largely because so many sources seem to offer conflicting definitions. For instance, Klein's Organic Chemistry mentions that ...
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1answer
96 views

Why Guanidine is called as strong base

I've studied pka of H2O as 15 and anything with a pka lower than it should be a acid . Guanidine has a pka of 13.8 and is being called as strong base . Why is it so. https://en.m.wikipedia.org/wiki/...
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2answers
61 views

Questions on Neutral oxides

Neutral oxides, are non metal oxides which are neither acidic nor basic. I have noticed a pattern for neutral oxides which I am unsure actually holds true. $\ce{CO}$, $\ce{H2O}$, $\ce{NO}$ and $\ce{...
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2answers
70 views

Why ammonium hydroxide precipitates metal salts?

When I was going through the chapter on pnicotgens, I got to know that ammonia acts as a Lewis base and it dissociates in water giving out hydroxide ion and the further hydroxide of ammonia, which we ...
0
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1answer
103 views

What alkali and alkaline earth metal oxides will turn moist red litmus blue and finally white? [closed]

How many of the following will turn moist red litmus blue and finally white? $\ce{Li2O}$, $\ce{KO3}$, $\ce{RbO2}$, $\ce{Cs2O2}$, $\ce{BeO}$, $\ce{MgO}$, $\ce{BaO2}$, $\ce{SrO}$. Since bleach ...
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1answer
36 views

Wouldn't adding a proton acceptor still make a solution just as acidic?

Say if you add NH3 to a solution, and it accepts a proton, it still becomes NH4+ in a solution, which is also acidic. A base should decrease the hydrogen ion concentration in a solution, but how does ...
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1answer
27 views

Organic Layer/Aqueous Layer Question [closed]

I could not answer this question, it would be appreciated if someone could help.
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2answers
142 views

Is Fe(OH)2 soluble in alkalis?

I have just started inorganic chemistry in school and I have just learnt about metal aqua ions and how they react in water. I learnt that $\ce{[Fe(H2O)6]^2+}$ reacts in water by losing a $\ce{H+}$ ...
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0answers
34 views

Dissociation equilibrium for nicotinic acid [on hold]

Nicotinic acid is an amphoteric compound. Does it mean that in very low $\mathrm{pH}$ it will be more soluble? Would the following be possible? $$ \begin{align} \ce{H2X+ &<=> H+ + HX}\\ \...
3
votes
1answer
43 views

How can I increase the viscosity of dilute hydrochloric acid

I'm cleaning the mortar off a new clinker brick wall. Walls actually. I hate this job. The builder told me to wash down the wall with weak HCl, leave it for a minute or two, and then spray it off with ...
2
votes
3answers
96 views

pH of 0.05 M NaH2PO3

What is the pH of a $\pu{0.050 M}$ solution of $\ce{NaH2PO3}$? I am given that $\mathrm{p}K_\mathrm{a1} = 2.0$ and $\mathrm{p}K_\mathrm{a2} = 6.58$. I am getting two different answers, $3.94$ and $4....
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0answers
44 views

Looking for experimental data for titration curves

I am looking for real, open source and free experimental dataset (not image, scan of table) of acid/base titration curves: pH versus titrant volume for many combination (strong/weak acid/base, ...
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1answer
64 views

Reaction between carboxylic acids and amines

Would some be able to explain why when I mix a carboxylic acid, like ethanoic acid, and an amine, say ethylamine, I get ethylammonium ethanoate. But when I mix a bi-functional group carboxylic acid (...
7
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0answers
41 views

Exceptionally weak basicity of pyridine [duplicate]

It is often explained that the relatively lower basicity of pyridine, relative to most amines, is due to the fact that the $\ce {N}$ lone pair resides in an $\ce {sp^2}$ hybridised orbital, instead of ...
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1answer
48 views

Acidity of carbonate ions creates paradox?

Whilst I understand why salts can be acidic or basic, the carbonate reaction confuses me (carbonate being a basic ion). $$\mathrm{{CO_3}^{2-} + H_2O \ce{<=>} {HCO_3}^- + OH^-} \\ \mathrm{{...
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1answer
72 views

Aromaticity fails?

Why is cyclopentadiene ($\mathrm{p}K_\mathrm{a} = 16$) less acidic than A) 2,4-pentanedione ($\mathrm{p}K_\mathrm{a} = 9$); B) phenol ($\mathrm{p}K_\mathrm{a} = 10$)? C) Even H20 (pka = 15.7) ...
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0answers
51 views

What is the benefit of using a pH indicator reagent over pH strips or a meter?

I've recently started getting into chemistry a bit as a hobby. Nothing serious, just amateur level stuff mostly, primarily just to educate myself. Whenever I need to determine the pH level of a ...
1
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1answer
44 views

Dissociation behaviour of polyelectrolytes

Assuming a solution of 100 polycationic molecules, each of them carrying 100 amino groups and an apparent pKa of 6.5. Would it mean that, at a pH of 6.5, 50 molecules will be fully protonated 50 ...