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).
2
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1answer
23 views
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
votes
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
votes
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
votes
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 ...
1
vote
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
votes
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 ...
0
votes
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 ...
-2
votes
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 ...
-1
votes
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 ...
-2
votes
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 $\ce{CO2}$.
...
1
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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 ...
-1
votes
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, ...
-1
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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 (...
-1
votes
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)...
-1
votes
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?
0
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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 ...
-1
votes
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
votes
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 ...
-1
votes
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^...
-1
votes
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
vote
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 ...
0
votes
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 ...
1
vote
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?
0
votes
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
votes
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 ...
1
vote
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
votes
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- + ...
-1
votes
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
votes
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_\...
-1
votes
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 ...
4
votes
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 ...
1
vote
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 ...
-1
votes
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/...
-1
votes
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{...
0
votes
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
votes
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 ...
-1
votes
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 ...
-1
votes
1answer
27 views
Organic Layer/Aqueous Layer Question [closed]
I could not answer this question, it would be appreciated if someone could help.
3
votes
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+}$ ...
-1
votes
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....
0
votes
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, ...
1
vote
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
votes
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 ...
-2
votes
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{{...
0
votes
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)
...
0
votes
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
vote
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 ...
