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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10
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3answers
22k views

Why does the pH of soft drinks get lower as they go flat?

I am doing an investigation about the chemistry of soft drinks and as part of this I observed the effect of time on the pH of soft drinks fully expecting the pH to increase as the carbonic acid, a ...
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0answers
12 views

Base/acid reaction -> alcohol amphoteric? why no pkb value?

I have a question concerning acid/base reactions. Is it true that an alcohol is a better base than water? My Professor listed the basicity (because we talked about E1/E2 and Sn1/Sn2 reactions) of the ...
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0answers
9 views

What is the equation for reaction between sodium citrate acidic buffer and sodium bicarbonate? [closed]

Trisodium citrate has a pH of 6.0 whilst the sodium bicarbonate I used was quite basic with a pH of 10.0±
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1answer
26 views

What concentration is phenolphthalein indicator ? 1% or 0.1%

I read some information about phenolphthalein indicator, some websites suggested phenolphthalein indicator of 1%, others mentioned phenolphthalein indicator of 0.1%. What is the difference of both of ...
-2
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0answers
11 views

What is the formula for the reaction between aqueous sodium carbonate and trisodium citrate buffer [closed]

I reacted these two in an experiment. I understand that when sodium carbonate reacts with water it forms sodium hydroxide. So, is the OH- from the sodium hydroxide that reacts with the trisodium ...
3
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1answer
59 views

Acidity of thiamine - how comes hydroxide anion with pK about 15 ionizes thiamine with pK about 18?

Textbooks say removing proton from thiamine's C atom will produce a resonance stabilized carbanion which is hence bioactive. That's OK, but how comes that 1) we abstract the acidic proton with the OH ...
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0answers
29 views

Why is [H2F+][SbF6-] the strongest Lewis acid

I have seen a similar question asked but there seems to be no answer rather a discussion on specifics. Wikipedia says that fluoroantimonic acid is the strongest conventional acid for liquids. The ...
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0answers
496 views

What are acid/base sensitive groups?

My textbook says that Clemmensen Reduction cannot take place in the presence of an acid-sensitive group and the Wolf Kishner reaction won't happen in the presence of a base sensitive group, citing $\...
18
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2answers
7k views

Why is H2SO4 a good dehydrating agent while other strong acids are not?

I understand that $\ce{H2SO4}$ is a very good dehydrating agent because it is a strong acid, so that it quickly donates $\ce{H+}$ to hydroxide ions in water to form $\ce{HSO4-}$ and $\ce{H3O+}$ .But ...
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0answers
14 views

Neutralising weak acid solution using readilly accessible substances [closed]

What could be a cheap, cost effective way to consistantly neutralise large, cumulative amounts of a weak acid solution using readilly accessible substances?
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1answer
37 views

Why does the pH of a weak acid not increase by 1 when diluted by a factor of 10? [closed]

Strong acid pH increases by one unit when diluted by a factor of 10, but why do weak acids not?
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1answer
24 views

Acid-Base Titration of ammonium dihydrogenphosphate?

How can I determine the concentration of ammonium dihydrogenphosphate solution? In this compound, the ammonium cation and the dihydrogen anion are both weak acids. I have a weak solution of this salt, ...
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0answers
21 views

Identifying which lone pair is more basic?

In the the compound RCONH2 which lone pair is more basic? Is it the lone pairs on Oxygen atom or the lone pair on Nitrogen atom. I believe that as O is more electronegative than N, the lone pair on O ...
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2answers
1k views

pH level of fabric with regard to inhibiting fungal growth

Someone on another forum made the point that doing laundry with sodium hypochlorite (bleach) will kill any fungus such as athlete's foot fungus, but that after the fabric dries, the pH level of the ...
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3answers
10k views

Why are acids usually depicted in fiction as green?

In cartoons, etc., acid is generally shown as vividly green, as in this scene from the Simpsons: We even have the colour "acid green". But when I used to use acids in chemistry class, they weren't ...
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0answers
35 views

Why does concentrated sulfuric acid have a strong affinity for water? [duplicate]

I have recently studied the laboratory preparation of hydrogen chloride gas, HCl, and the purification process involves the passage of the HCl has through concentrated sulfuric acid, H2SO4, to remove ...
3
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1answer
50 views

Preparation of ammonium acetate buffer for HPLC

Buffer solutions are typically prepared by dissolving an appropriate salt in water and then adjusting the $\mathrm{pH}$ to the desired position by addition of the conjugate acid or base. For example, ...
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0answers
34 views

Finding the best indicator for titration of a weak base and strong acid (NH3 + HCl) with only a Ka value

The best indicator to use in a standard titration of aqueous $\ce{NH3}$ $(K_\mathrm{a}(\ce{NH4+}) = \pu{5.7E-10})$ with an $\ce{HCl}$ is $$ \begin{array}{llc} \hline & \text{Indicator} & \...
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1answer
29 views

Is there a notion of generalized acidity for lithium ions?

From my understanding, the basic notions of acidity can be explained by considering a cup of pure water, and then adding a substance to it which creates either free $\ce{H+}$, or free $\ce{H3O+}$ and $...
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0answers
23 views

What are the compounds in oxygen and carbon dioxide indicator solutions that gives their color?

My brother had some leftover oxygen and carbon dioxide indicator solution for one of his take-home experiments from school, so he let me have them. I want to use them for an experiment and write out ...
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2answers
59 views

Does carbonation permanently increase the acidity of soda water?

If you carbonate water, and then expose the resulting soda water to the atmosphere and wait until it goes completely flat, will the (former) soda water end up more acidic in final equilibrium than ...
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0answers
15 views

Where can I find literature values for standard molar enthalpies of neutralization?

I'm looking for enthalpy of neutralization literature values for inorganic weak acids. NIST, PubChem, etc. don't list them. Is there somewhere else I should look?
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1answer
26 views

Comparing basic strengths between pyridine and 1,2-dihydropyrazine

Compare the basic strengths of above two compounds. In the first compound (1,2-dihydropyrazine), the lone pair of one N will participate in resonance but the lone pair of other N will not, similarly ...
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0answers
35 views

CaCl2 and Citric Acid react /w metal pot

I'm building a dehumidifier based on $\ce{CaCl2}$-solution as descant, which is to be regenerated by heating and evaporation. I thought it would be a good idea to add some citric acid to combat chalk-...
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0answers
62 views

How to find the moles of a salt added to a weak base, given ph

I would really appreciate some help with how to approach this: I'm given that: Methylamine (CH3NH2) is a weak base used in the manufacture of pesticides. Taking into account that the degree of ...
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0answers
18 views

Is sodium aquo complex a Brönsted-Lowry acid?

I know that according to Brönsted-Lowry theory, a base is a proton acceptor while an acid is a proton donor. Also, the acid-base pair that differs by a single proton is a conjugate pair. If this is ...
3
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1answer
54 views

Reaction between barium peroxide and hypochlorous acid

When $\ce{BaO2}$ reacts with $\ce{HClO},$ the question tells us that that oxygen, barium chloride and one other product is formed. The equation I came up with is $$\ce{BaO2 + 2 HClO -> BaCl2 + 2 O2 ...
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3answers
15k views

Difference in acid strength of oxalic acid and malonic acid

Despite very similar skeletal structures, the difference in acid strength between oxalic acid (ethanedioic acid) and malonic acid (propanedioic acid) is quite significant. What is the reason for that? ...
2
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1answer
84 views

Isn't water a Lewis base in the ammonia–water reaction?

Exactly one of these statements is false. Which one? (a) When ammonia dissolves in water, the latter behaves as a Lewis base. (b) The conjugate acid of $\ce{H-}$ is $\ce{H2}.$ (c) Boric acid is a ...
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3answers
1k views

Is the proton the strongest acid?

Having looked at the various definitions of acids and bases and having refined my understanding of it after learning about the inadequacies of pKa and the novel use of the Hammett acidity function, I ...
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0answers
32 views

Number of lone pairs as a measure of basicity [closed]

$\underline{\text{Consider the following question:}}$ The first difference I noticed in these compounds was the large number of oxygen atoms in (IV). This definitely means that there is a larger ...
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1answer
24 views

Double Equivalence Point Calculations for Oxalic Acid [closed]

Question: Oxalic Acid, H2C2O4 has two pKa values, 1.25 and 4.27. A 0.100 M solution of oxalic acid was titrated with a 0.100 M solution of HaOH. What is the pH at the second equivalence point? a) 1.23 ...
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3answers
8k views

Order of Basicity of Nitrogen Trihalides

I was asked to arrange nitrogen tri-halides in order of increasing basicity. On looking up the answer online, it turned out to be the following: $\ce{NF3}$ < $\ce{NCl3}$ < $\ce{NBr3}$ < $\ce{...
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0answers
528 views

Which one is the stronger acid among these two compounds?

According to me, acidity for these two compounds depends primarily upon two factors: inductive effect due to the ring electronegativity of the atom bearing the hydrogen atom If the first factor ...
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1answer
58 views

What's the chemical reaction between coffee and sodium bicarbonate? [closed]

Every morning I put sodium bicarbonate into my coffee and I was wondering what chemical reaction this produces and what are the chemicals produced at the end. I cannot find an answer to this question ...
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1answer
92 views

Why is dilution exothermic?

The breaking of bonds usually absorbs energy and forming bonds usually releases energy. Then, why is the dilution of acids and bases exothermic?
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2answers
4k views

Reuse 20 litre plastic drums for drinking water?

Would you consider it safe to clean and reuse a 20 litre plastic drum that contained 36% Hydrochloric Acid for drinking water? If so how would you recommend cleaning it?
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1answer
835 views

Why is guanidine considered a strong base?

I've studied $\mathrm{p}K_\mathrm{a}(\ce{H2O}) = 15,$ and anything with a $\mathrm{p}K_\mathrm{a}$ lower than should be an acid. Guanidine has a $\mathrm{p}K_\mathrm{a}$ of $13.8$ and is being called ...
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1answer
58 views

Order of Lewis acid character among sulfur hexafluoride, sulfur tetrafluoride and tetrachloromethane

Problem Compare the order of Lewis acid character of $\ce{SF6},$ $\ce{SF4}$ and $\ce{CCl4}.$ My attempt Oxidation state of $\ce{S}$ in $\ce{SF6}$ is $+6,$ so it is very electrophilic. $\ce{S}$ has a ...
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2answers
57 views

In the pH system of acids and bases, are there 10^-7 loose ions per liter (at pH of 7) or per mole of solvent? (Or per mole of total substance?)

Most places tell me that the number on the pH scale tells you the number of dissociated ions, in moles, per liter of substance. But, Wikipedia's article pH says this....: ... For a commonplace ...
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1answer
75k views

Baking Soda + Citric Acid + Water = CO2, how much though? [closed]

Baking soda (sodium bicarbonate) + citric acid react when mixed with water to form some amount of carbon dioxide gas ($\ce{CO2}$). I am trying to determine what percentage of the products is carbon ...
3
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1answer
206 views

Why are the acidities for H-CH3 and H-OH so different?

I was comparing the acidity of H-CH3 and H-OH, and a lot of things weren't making sense. Generally, the process of turning H-X into $H^{+}$ and $X^{-}$ can be broken into 2 hypothetical steps: 1.) ...
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1answer
45 views

Why are some weak acid equilibrium approximations invalid in very dilute solutions?

Using two approximations for the dissociation of a weak acid, we can write $$K_\mathrm{a}= \frac{[\ce{H+(aq)}]^2}{[\ce{HA(aq)}]}$$ One of these two approximations we use is that the concentration of ...
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2answers
233 views

Does Magnesium metal react with carbonic acid?

I use rainwater in my house for my water supply. I collect the water in plastic lined tanks. Some of my piping at home is copper, and I have blue stains in my shower, because I think the copper from ...
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3answers
57 views

Difficulty in understanding ionisation of sulphuric acid [closed]

$\ce{H2SO4}$ when added to water. $\ce{H2SO4 + 2 H2O -> SO4^2- + 2 H3O+}$ My sir explained me these reaction as $\ce{H}$ will give $\ce{2 H^+}$ ions to the base $\ce{H2O}$.So why does it not become ...
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1answer
2k views

What is the reaction between plain soda and sugar?

Today I was having lunch and I ordered plain soda. And some amount of sugar was added, suddenly all the liquid fell of the glass. I thought there should have been a reaction between plain soda and ...
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4answers
114k views

How do you explain pKa to non-professional?

Let's say we have substance $\ce{A}$, which is mixed with substance $\ce{B}$ to improve shelf-life because $\mathrm{p}K_\mathrm{a}$ of the substance $\ce{A}$ is $7.9$ and in mix the $\mathrm{pH}$ is $...
3
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2answers
2k views

Application of limiting reagents and acid-base stoichiometry

I'm having a bit of trouble with the latter questions of this problem. $\pu{15.0 mL}$ of $\pu{1.4 M}$ $\ce{HCl}$ was mixed with $\pu{1.00 g}$ of $\ce{CaCO3}$ until all the solid had dissolved. The ...
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1answer
58 views

Is there an “off the shelf” way to make magnesium ascorbate? [closed]

I make my own sodium ascorbate with ascorbic acid and sodium bicarb. It's easy, I get the vitamin c off ebay and the baking soda from the store. Is there a similar way to make magnesium ascorbate: ...
2
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1answer
48 views

Stability of pyridine derivatives

Arrange the following pyridine derivatives in the order of increasing stability of adduct formed with $\ce{BBr3}.$ Explain briefly. I'm pretty confused about which structure is the most stable. I'd ...

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