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
2k views

Enthalpy of neutralization of strong acid and strong base differing from enthalpy of formation of water from ions

If the neutralization between strong acid and bases has enthalpy of neutralization of around $\pu{-57.1 kJ mol^-1}$, why is it that when I try to calculate the enthalpy of formation of water from $\ce{...
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1answer
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Why is magnesium sulfate acidic? Why are my calculations showing that it is basic?

Let's say I was dissolving $\pu{1M}~\ce{MgSO_4}$ into water and I wanted to find the pH. I would go right to the reaction of the dissociation of $\ce{Mg(OH)_2}$: $$\ce{Mg(OH)_2 <=> Mg^2+ + 2OH-}...
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2answers
84 views

Acidic nature of boric acid when its concentration high

Following statement was given for boric acid $(\ce{H3BO3}):$ At low concentrations $(\leq\pu{0.02 M})$ essentially $\ce{B(OH)3}$ and $\ce{B(OH)4-}$ are present, but at higher concentration the ...
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1answer
24 views

Limiting fraction of association

Show that the limiting fraction of association of a base in water, as the concentration of base approaches 0, is $$\alpha=\frac{10^7 K_b}{(1+10^7\times K_\mathrm{b})}.$$ I have tried this problem ...
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1answer
70 views

Why there is a huge difference between the basicity of urea and guanidine?

The two molecules have very similar structures, but urea has a $\mathrm{p}K_\mathrm{b}$ of $13.9,$ while guanidine have a $\mathrm{p}K_\mathrm{b}$ of $0.4.$ If guanidine cation can be stabilized by ...
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0answers
22 views

Pyridinium ion in inositol nicotinate

I have read about inositol nicotinate which is used as a medication for deficiency in vitamin B-3. I think that if acetic acid was applied to this medication it would form pyridinium ion and acetate ...
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23 views

∆G° and ∆G°' for acid dissociation

For the dissociation of an acid AH, where $\ce{AH <=> A- + H+}$, if $∆G°$ is $\pu{+25 kJmol-1}$ at $\pu{300 K}$, what is $∆G°'$? I know that for $∆G°$, $\ce{[H+]}$ is $\pu{1M}$, whereas for $∆G°'...
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14 views

What is the order of acidity for hydrogens in primary, secondary and tertiary alkanes, alkenes, and cycloalkanes [duplicate]

The bond dissociation energies of C-H bonds in alkanes, alkenes and aromatic compounds decrease in the following order: primary > secondary > tertiary > allylic > benzylic. The weaker the bond, the ...
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1answer
132 views

Understanding the increase in pH of a buffer solution upon incremental additions of NaOH analytically

So let's say we have $200\ \mathrm{mL}$ of $1\ \mathrm M$ $\ce{CH3COOH}$ solution. In this solution we have the equilibrium $\ce{CH3COOH <=> CH3COO- + H+}$. To that we add $100\ \mathrm{mL}$ of $...
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0answers
123 views

Does aniline react with FeBr₃?

I have read that aniline does not undergo Friedel–Crafts reaction because it complexes with Lewis acid $\ce{AlCl3}.$ Will it also react with $\ce{FeBr3}$ during bromination (to receive a 3-bromo ...
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1answer
28 views

Does reaction of alkali and alkaine earth metals' reaction with water an acid-base reaction? [closed]

In my chemistry notes the teacher gave me the note that reaction of alkali, alkaline earh metals' reactivity with water, acids(e.g. H2S) increases down the group and bases(e.g.NH3) decreases down the ...
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1answer
47 views

Comparing basic strength order of amines

In the above question I was asked to compare the basic strength order. So I did it like this: The Nitrogen in I and II will not participate in resonance so the only effect it could produce is ...
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2answers
2k views

Lewis Acid / Base reaction for SO2 and H2O

I am having trouble with this question: Identify the Lewis acid and Lewis base in each of the following reactions: $\ce{SO2(g) + H2O(l) = H2SO3(aq)}$ What I tried: A Lewis acid is an electron pair ...
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1answer
212 views

Examples of Lewis base nature of sulfur dioxide

I have read that sulfur dioxide acts as both Lewis base (due to presence of lone pair over $\ce{S}$ and/or $\ce{O})$ and Lewis acid (due to presence of vacant d orbital). I found many examples of $\ce{...
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17 views

Acidity comparison on R-PO3H2

Question Compare the acidity $(K_\mathrm{a1})$ of the following three acids: $\ce{H3PO4},$ $\ce{Ph-PO(OH)2}$ and $\ce{H3C-PO(OH)2}.$ Thoughts These three acids are of type $\ce{R-PO3H2},$ where ...
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1answer
35 views

Does clove oil/eugenol interact with nylon type plastics?

So I am aware that the eugenol in clove oil readily melts #6 type plastic (polystyrene). Polypropylene has a higher resistance, while HDPE type plastics seem to have the highest resistance. My main ...
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1answer
54 views

Difference between neutral and amphoteric oxides

What is actual difference between neutral oxides (e.g. $\ce{NO},$ $\ce{N2O},$ $\ce{CO})$ and amphoteric oxides (e.g. $\ce{Al2O3})?$ I got a hint of it from the comment of Ivan Neretin.
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2answers
173 views

why Ammonia is proton acceptor

I understand that this is an elementary question, but I tried to find answers which I could not get. I am trying to understand why Nitrogen in Ammonia is a proton acceptor. Now as I can see from the ...
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1answer
5k views

How to calculate pH of the Na2CO3 solution given ambiguous Ka values

This is the exact question I faced on an exam. Calculate the pH of $\pu{0.05 M}\ \ce{Na2CO3}\ (\ce{H2CO3}: K_\mathrm{a,1}= 4\times 10^{-7},\ K_\mathrm{a,2}= 4.7\times 10^{-11})$ Solution $$\ce{...
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2answers
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What makes protons give the property of acidity?

Brønsted Lowry definition of an acid says that an acid gives away protons. What I don't understand is what makes dissolved protons grant the property of acidity? Like, why would dissolved protons eat ...
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2answers
6k views

How can I remove acids from cola?

I would like to taste Pepsi-cola without acid. I like it's flavor but don't like acidic taste. It's acidity comes from carbon dioxide, phosphoric and citric acids (see ingredients list in wiki and ...
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1answer
76 views

Easy way to make carbonic acid from other chemicals? [closed]

I would like to test for the reaction between carbonic acid and copper (to simulate the effect of acid rain on copper). However, I find that many supplies failed to provide carbonic acid (either in ...
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1answer
35k views

How do I calculate the concentration of sulphuric acid by a titration experiment with sodium hydroxide?

In my latest chem lab the objective was to create a primary standard of $\ce{NaOH}$ and use it to determine the concentration of sulfuric acid. The first part of the lab was determine the molarity of ...
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1answer
47 views

Why is CO2 more likely to dissolve in a basic solution than an acidic solution? [closed]

I'm having trouble thinking through this problem. I know that when $\ce{CO2}$ dissolves in water it can release $\ce{HCO3-}$ and $\ce{H+}$ and cause a drop in pH. But can I use this to justify why $\...
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2answers
7k views

Titration of H2SO4 w NaOH: Solving for the molarity of H2SO4?

I am given $\ce{H2SO4}$ in a reaction vessel of about $50~\mathrm{mL}$. I need to solve for the molarity of $\ce{H2SO4}$. A $10~\mathrm{mL}$ sample of $\ce{H2SO4}$ is removed and then titrated with $...
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1answer
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Comparing Acidic Strength of H3PO4 and H3AsO4

The $pKa$ values for H3AsO4 and H3PO4 are $2.30$ and $2.12$ which indicate that H3PO4 is a stronger acid compared to H3AsO4. I looked up their electronegativity values to find that they are almost the ...
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0answers
21 views

Is it feasible to measure the pH of solution consisting of hydrofluoric acid, methanol and water using redox potential method?

Is it feasible to measure the pH of $\ce{HF}:\ce{H3COH}:\ce{H2O}$ solution using redox potential method? Can I use this method to calculate the $\ce{H+}$ ions in this solution and specifically, can I ...
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1answer
246 views

Equivalence point vs inflection point in the titration curve of a weak acid

Let's suppose we want to titrate a solution containing an unknown monoprotic and weak acid. We use a strong base, such as $\ce{NaOH}$. When the number (and moles) of hydroxide ions coming directly ...
37
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4answers
42k 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 ...
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1answer
27 views

Ligand substitution reaction in coordination compounds

I know that the following substitution reaction can take place: $$\ce{[Cu(H2O)4]^2+ (aq) + 4NH3 (aq) -> [Cu(NH3)4]^2+ (aq) + 4H2O (l)}$$ This is because ammonia is a stronger ligand than water. ...
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2answers
187 views

Does H3CO3+ ion exist and what is its structure? [closed]

Why doesn't $\ce{H3CO3+}$ ion exist and why doesn't the carbonyl group in carbonic acid $(\ce{H2CO3})$ seem reactive?
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1answer
386 views

Using acidic detergents

If detergents were acidic rather than basic, can we still achieve a clean surface? What would be more effective? Strong acid or a weak acid? How would the result of cleaning be different if an acid ...
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1answer
4k views

How do cloves break down plastic?

When my family buys powdered cloves in bulk, we put them in plastic until we get home - which takes at very most an hour. As soon as we get home, we transfer them into glass because we have had issues ...
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0answers
59 views

How does the relative acidity of 2,3-dinitrophenol compare to that of 2,4-dinitrophenol?

I am assuming that the -I inductive effect in 2,3-dinitrophenol is stronger than in 2,4-dinitrophenol since it operates through less bonds, therefore on inductive grounds it should have a lower $\...
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2answers
45 views

Can I make a buffer with a weak acid without adding it's conjugated base, when the desired pH of the solution is exactly the pKa of the weak acid?

An acid will be 50% dissociated when the solution it's in have a pH equal to the acid pKa ('afirmation 1', for later reference). We also know that a good buffer solution have equal concentrations of ...
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1answer
33 views

Can hydrogen peroxide be considered an alkali? [closed]

Hydrogen peroxide is miscible with water, can neutralize acids, and produces H2O, but I've never seen it labeled as an alkali, could we still consider hydrogen peroxide an alkali?
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1answer
209 views

What is the most acidic neutral hydrocarbon?

This is a question I've been thinking about quite frequently. I had seen that this hydrocarbon has a low $\mathrm pK_\mathrm a$ with reference to the highlighted H-atom Loss of the central gives ...
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1answer
742 views

Acidic strength of organic acids. Substituted PhCOOH acids

Could someone please explain the order of acidity of ortho, para and meta substituted benzoic acids with the substituent as methyl group? Methyl group operates +I and +R effect, I believe.
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45 views

Is contribution to pH by an acid or base always greater than salt hydrolysis?

I was solving a titration question and the reaction I came to was this: $$ \begin{array}{lcccc} \ce{&BOH(aq) &+ &HCl(aq) -> &BC(aq) &+ &H2O(l) }\\ \text{Initial} & x &...
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28 views

Acidity of 2-sulfopropanedioic acid in water

Sulfuric acid is a strong acid ($\mathrm{p}K_\mathrm{a}$ value below that of $\ce{H3O+}$: completely dissociated in water) at its first deprotonation, but is a weak acid ($\mathrm{p}K_\mathrm{a}$ ...
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What metal is used to back this mirror?

My father is attempting to remove the mirror from a piece of glass. We stripped the black paint from the back and exposed the shiny surface with acetone. In the past he has been able to remove ...
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3answers
165 views

Acidity order of o-nitrophenol vs. o-chlorophenol [closed]

It is given that the above statement is true. Why does o-nitrophenol, in spite of intramolecular hydrogen bonding, have a lower $\mathrm{p}K_\mathrm{a}$ than o-chlorophenol?
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2answers
668 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 ...
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0answers
804 views

Rust removal with phosphoric acid created more rust

I wanted to remove the rust on numerous steel parts with phosphoric acid. After removing all the grease in trichloroethylene, I put my parts into a 50 % solution of phosphoric acid ad 40 °C for 5 ...
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1answer
47 views

how can I measure the pH of a HF:H2O:CH3OH solution? [closed]

how can I measure the pH of a HF:H2O:CH3OH solution? more specifically, how can I precisely and accurately measure the H+ ion concentration?
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2answers
6k views

How to increase the concentration of HCl

Today I have purchased some $\ce{HCl(aq)}$ on my local market with a concentration of 23%. However, I need to obtain a concentration of 37% in order to perform an experiment. Can I use distillation ...
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1answer
42 views

Ionization of hydrogens in hypophosphorous acid

Does anyone know why the hydrogen atoms bonded with phosphorus in $\ce{H3PO2}$ are not ionizable? I tried looking in high school level books, but they only describe the process, not the real reason. ...
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2answers
74 views

Acidic strength order in gaseous phase

I got this question in my exam: Arrange the following in increasing order of acidic strength in gaseous phase (i) $\ce{CH3CH2COOH}$ (ii) $\ce{CH3COOH}$ I felt that increasing order must be (i)...
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1answer
34 views

Order of magnitude of ions in water [closed]

My book says water has approximately $\pu{3.35E28 molecules/m^3}$ and that only a small part of water molecules are dissociated to $\ce{H+}$ and $\ce{OH-}$ ions and that the approximate amount of ...
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0answers
27 views

Rate Equation of Chemical Traffic Light (NaOH + Glucose + H20 + Indigo Carmine)

I am trying to find the Rate Equation of the Chemical Traffic Light Experiment. Wikipedia says the Blue Bottle Experiment (similar, but uses a different dye) has the following orders: The reaction ...

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