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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Why does acid hydrolysis of glucose-1,6-bisphosphate produce glucose-6-phosphate and not glucose-1-phosphate?

A paper I found details treating glucose-1,6-bisphosphate with 6M HCl to produce glucose-6-phosphate. I'm curious why glucose-1-phosphate (and then even plain glucose) isn't formed instead?
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1answer
40 views

How do you determine the NIE equation of a buffer? [closed]

For example, I have formic acid and sodium formate. How do I know the NIE(net ionic equation) equation is $\ce{HCHO_2 + H_2O <=> H_3O+ + CHO_2-}$ and not $\ce{HCHO_2 + OH- <=> H_2O + CHO_2-...
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Why is C2H5 a stronger +I group than CH3?

While reading about the basic character of amines, I came across a note which said that $\ce{CH3-CH2-NH2}$ is more stable than $\ce{CH3-NH2}$ as $\ce{C2H5}$ is a stronger +I group than $\ce{CH3}$. ...
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Factors affecting mass of a gas-evolving reaction mixture over time

Excess magnesium was added to a beaker of aqueous hydrochloric acid on a balance. A graph of the mass of the beaker and contents was plotted against time (line 1). What change in the experiment could ...
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3answers
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Why doesn't KI(aq) react with HCl(aq)?

When concentrated sulfuric acid is added to anhydrous potassium chloride and the fumes produced are bubbled into aqueous potassium iodide solution, the observed solution would be colourless solution. ...
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2answers
68 views

Is this stoichiometric question answerable? (unknown variable)

This question kind of borders on the fields of both semantics and math, as well as chemistry, but I still believe this is the right place to ask. On a test I took, a question was posed as such: Via ...
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2answers
323 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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0answers
48 views

Why is the side chain of lysine more basic?

According to the images below, the NH3+ on the side chain of lysine is less acidic than the NH3+ closer to the COO-. Why is this? Wouldn't the NH3+ have an intramolecular H-bond with a negatively ...
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9 views

How can I wet etch Nickel Chloride (NiCl/NiCl2) off a GaN sample

Apologies in advance for what may be a basic chemistry question - I'm asking from the point of view of microlithography. I have a Gallium Nitride sample which I have etched in a Ar/Cl plasma with a ...
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1answer
73 views

Finding Ka of a monoprotic weak acid from pH and concentration of added sodium salt

A solution of $\pu{0.36 M}$ of the sodium salt of a generic monoprotic weak acid $\ce{HA}$ has a $\mathrm{pH}$ value of $8.782.$ $K_\mathrm{a} = ?$ Why doesn't the following formula work in this ...
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Why doesn't base/acid reacting with water create a salt?

An acid/base nwutralization will create a salt + water. If one uses water itself as the acid or base, and have an acid/base neutralization, how come that doesn't create a salt? For example:$$ \ce{HCN(...
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807 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 ...
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1answer
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What is an alternate way of preparing a sodium hydrogen phosphate/sodium dihydrogen phosphate buffer through titrating an acid with a strong base?

So my friend and I are stumped. This is in the context of achieving the sodium hydrogen phosphate/sodium dihydrogen phosphate buffer by titrating the acid with a strong base. My friend says the answer ...
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What is the pKa of the hydronium, or oxonium, ion (H3O+)?

Although the wikipedia page on Hydronium indicates a $\mathrm{p}K_\text{a}$ of −1.74, I noticed in the discussion of this page that the subject seems debated (cf. http://en.wikipedia.org/wiki/Talk:...
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4answers
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The Reaction Between Nickel and Hydrochloric Acid

Having conducted an investigation involving multiple metals, I have found that nickel refuses to react with concentrated hydrochloric acid. I have even left the reaction overnight and still have seen ...
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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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2answers
71 views

Why is H2O a weaker acid than acetylacetone? Shouldn't a hydrogen connected to an oxygen be more acidic than a hydrogen connected to a carbon atom? [closed]

I recently started studying chemistry after a long pause in my education so pardon me if it is a simple question. In the organic chemistry course I am taking, the professor told us that the first ...
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1answer
38 views

Why did my vinegar not create the traditional volcano?

At the weekend, my son and I tried the volcano experiment. You know the one: vinegar introduced to sodium bicarb (and a little red dye) within a conical "volcano". Not actually ours; photo ...
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3answers
23k 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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26 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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1answer
60 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 ...
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1answer
60 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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754 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 $\...
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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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42 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
27 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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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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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
11k 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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1answer
85 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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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
67 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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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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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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63 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
24 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 ...
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1answer
58 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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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? ...
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1answer
94 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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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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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
27 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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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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529 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
77 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
160 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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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
947 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
73 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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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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