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 don't we use sodium bicarbonate to neutralise base spills?
According to this document on lab safety (http://faculty.washington.edu/korshin/Class-486/AEESP-safety-notes.pdf), it says to not use $\ce{NaHCO3}$ to neutralise specifically base spills, stating &...
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I tested the effect of temperature on the pH of carbonated water but the results seem to go opposite to what was expected. Could anyone explain?
We carried out an experiment to investigate the effect of temperature on the acid carbonate equilibrium in carbonated water. We tested 5 different temperatures (room temp, 2 above and 2 below) by ...
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Why is a protonated carboxylic acid less acidic than a protonated ester?
To my understanding, both have analogous resonance structures except that the ester has on -OR and the carboxylic acid has an -OH. Why is a positive charge on C-O-R more stable than on C-O-H?
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How to calculate the buffer capacity for polyprotic acids? specifically H2PO4 --- HPO42- + H30+
as the title says. Is b= amount of OH-/ H3O divided by volume of buffer x change in pH wrong to use with polyprotic acids? Can I calculate the buffering capacity of a sodium phosphate buffer made up ...
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What does "acidic" mean in an article on hydrogen boride nanosheets?
From Rojas et al. [1] (emphasis mine):
On the other hand, we found that proton exchange with HB occurs in water with the estimated $\mathrm{p}K_\mathrm{a}$ of $3.5\pm 0.2,$ even after reactive sites ...
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Why do vessels get a better shine when tea-leaves are soaked overnight in it before washing?
The other day I dumped consumed tea leaves into a brass utensil because I needed the tea-pan urgently. The vessel with the tea leaves didn't get around for cleaning until the next day. Ergo, the tea ...
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If I have a mixture of potassium hydroxide and sodium hypochlorite, what will be the result of adding citric acid or ascorbic acid? [closed]
I have a cleaning chemical that is $\pu{10\%}$ potassium hydroxide ($\ce{KOH}$}) and $\pu{5\%}$ sodium hypochlorite ($\ce{NaClO}$). What is the result if I add citric acid ($\ce{C6H8O7}$) or ascorbic ...
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How do common histological stains work?
In histology there are commonly used acidic (= negatively charged) dyes, like eosin, erythrosine, orange G, and basic (= positively charged) dyes, like haematoxylin, toluidine and methylene blue, ...
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Is it possible to (naturally) change alkalinity without changing pH?
The Bjerrum plot shows how the different species of dissolved inorganic carbon (DIC) are distributed in sea water as a function of pH. The higher the pH, the more carbonate ion, less dissolved $\ce{...
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How to calculate the pH value of a Carbonate solution?
I read the similar questions suggested when submitting my question but they didn't help me How can one calculate the pH of a solution? How to calculate pH of the Na2CO3 solution given ambiguous Ka ...
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Why does base aspirin hydrolysis work better than acid aspirin hydrolysis? [duplicate]
Why does base aspirin hydrolysis work better than acid aspirin hydrolysis?
I conducted an experiment and found that there was greater Salicylic Acid yield for the one I added base compared to the one ...
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How to understand the acid-base properties of a molecule with many functional groups: example biotinyl-5'-AMP
Background
I'm interested in the acid-base properties of a metabolite, biotinyl 5' AMP in the cell. Biotinyl-5'-AMP can react with protein lysine side chains at the anhydride linkage to form biotinyl-...
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What are the relevant pK values on HEPES?
HEPES is 2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethane-1-sulfonic acid. I have read (MA Al-Ghobashy, Bull of Faculty of Pharmacy, Cairo University 2014; 52: 71-78) that the sulfonic acid group is ...
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Rates of a chemical reaction
Consider the reaction between Calcium Carbonate and Hydrochloric Acid. I understand the reaction rate can be increased by increasing the concentration of reactants. However I can't seem to understand ...
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Purpose of a pH Problem
I was doing a multiple choice question as follows.
The pH scale measures the
Strength of an acid
Concentration of hydrogen ions
Strength of hydrogen ions
Concentration of an acid
The answer is 2 but ...
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Why is parafluorophenol is more acidic than phenol?
I have learnt that the +Mesomeric effect (+M effect) of fluorine at para position dominates its -Inductomeric (-I effect) nature. If we see that the acidic strength (with the help of stability of ...
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Calculate the concentration of HF in aqueous solution of NH4F and NH4HF2 mixture
There is a similar question on this site, but here i have a mixture.
I have a mixture of NH4F (35% weight) and NH4HF2 (8% weight) in water. How do I calculate the weight % expressed in HF? or the ...
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How do you calculate percentage acidity?
I am looking to calculate the percentage acidity of different drinks for the purposes of devising cocktail recipes. According to Liquid Intelligence by David Arnold, the optimum acidity level is 0.7-0....
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Does concentrated HNO3 oxidize aluminium to form a protective oxide layer, or is the oxide layer already present so HNO3 is unable to react? [duplicate]
Sources on the internet like this one only say that aluminium does not react with concentrated or dilute $\ce{HNO3}$.
I have seen other related questions on this site but none answers my question ...
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Finding the pH of a solution from neutralizing hydrochloric acid and potassium hydroxide
What is the pH of the solution if $\pu{30.58 cm3}$ of hydrochloric acid ($\ce{HCl}$) with a concentration of $\pu{0.2855 mol dm-3}$ and $\pu{29.41 cm3}$ of potassium hydroxide with a concentration of $...
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What other acids can replace hydrochloric acid in the production of galvanized steel?
Galvanized Steel undergoes several processes before being lowered into a molten zinc bath. One is cleaning the steel with "an acidic solution to remove mill scale."
After some more research ...
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Is calcium carbonate a Brønsted–Lowry base, a Lewis base, or both? [closed]
What type of base would $\ce{CaCO3}$ be in the following example:
$$\ce{CaCO3 + H2SO4 -> CaSO4 + CO2 + H2O}?$$
My understanding is that calcium carbonate cannot be a Brønsted–Lowry base because ...
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What happens when you mix a salt with a strong base? [duplicate]
This doesn't come off from a question but it came to my mind. Take an example of $NH_4Cl$ as the salt and $NaOH$ as the strong base. What would happen to the pH for example? I'm guessing that the salt ...
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Can helium hydride ions eat through teflon?
Searching on the internet for a really powerful acid, I came across a species called helium hydride ion which is estimated to have a $\mathrm{p}K_\mathrm{a}$ of $-63,$ making it orders of magnitude ...
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Calculating the pH of an exteremely dilute solution (3.6×10^-9 M) of weak acid [closed]
I've got a question about analytical chemistry that I'm having trouble solving:
For a $\pu{3.6 \times 10^{-9} M}$ solution of 1-naphthoic acid, calculate the $\mathrm{pH}$ $\left(K_\mathrm{a} = 2.1 \...
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Find the required water volume to add so that the pH of two solutions will be the same
Question.
We have two flasks: one contains 50 mL of 0.001 M HCl and the other 50 mL of 1M acetic acid.
a) How much water should be added to the more acidic solution so that the pH of the two ...
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How to find the amount of ions from the dissociation of a weak acid? [duplicate]
Someone asked me this question,"How many ions are formed during the dissociation of 500 molecules of carbonic acid, if it dissociates in the first degree by 20%, and in the second degree by 1%?&...
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Why doesn't hydroxide associate with water analogously to proton forming hydronium?
I'm a novice at chemistry. I've heard that an acid needs water to show its acidic properties, that's why nitric acid needs to be associated with water to show its acidic properties:
$$\ce{HNO3 + H2O &...
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Reaction of lead with acetic acid and hydrogen peroxide solution
My textbook says lead reacts with acetic acid when there is enough oxygen to oxidize lead:
$$\ce{2 Pb + O2 + 4 CH3COOH -> 2 Pb(CH3COO)2 + 2 H2O}$$
So, I added lead into mixed solution of acetic ...
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Why are the phosphate ion and hydrogen phosphate not conjugate acid/base pairs of each other?
(e) Identify in the following reaction the Bronsted-Lowry acid and its conjugate base
$$\ce{PO4^3- + HNO3 -> NO3- + HPO4^2-}$$
Both $\ce{PO4^3-}$ and $\ce{HPO4^2-}$ differ by a $\ce{H+}$ ion so ...
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Why phenolphthalein is not completely neutralized in basic solutions? [closed]
Phenolphthalein $(\ce{HIn})$ is slightly acidic. Why doesn't it completely break down into $\ce{H+}$ and $\ce{In-}$ and also reacting with all of the $\ce{OH-}$ ion present, unlike $\ce{NaOH}$ and $\...
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Why does chlorine displace bromide
Found that chlorine will displace bromide, and iodide from their ion forms. According to my textbooks, this is because chlorine is more electronegative than bromine and iodine. However, the chloride ...
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Are acids effective in removing soap scum?
In my experience, most of the commercial products intended for removing soap scum from bathroom surfaces are ineffective. No matter how long you leave it on or how hard you scrub, the soap scum doesn'...
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What happens to the hydroxide ion concentration when you add caustic soda to ammonia?
Question.
Find the $[\ce{OH-}]$ and the pH of a $\pu{0.20 M}$ $\ce{NH3}$. If given $\pu{1 L}$ of the previous solution, when adding $\pu{100 mL}$ of $\pu{0.2 M}$ $\ce{NaOH}$, what would be the new ...
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The difference between Zn and Al on acid and base reaction
Because it was written on my textbook that Zn and Al dissolves in acid and alkali, I tried.
When I put Al in NaOH solution it reacted immediately. But when I put Zn in the same concentration of NaOH ...
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Predicting acid-base equilibria
I was looking at acid-base equilibria of weak acids and weak bases. To determine the equilibrium constant of a reaction of those, I found a formula on the libretexts page:
Where ΔpKa is the ...
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How does having a basic stationary phase help the separation of acidic/basic compounds from non acidic/basic ones?
I have to reason whether silica or alumina would be a better choice of stationary phase for separating a mixture of pyridine and cyclohexanone with column chromatography.
I would expect both pyridine ...
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Can a weak acid ever fully dissociate?
From what I understand, the pH of the solution the weak acid is added to determines the extent that the weak acid will dissociate. But would there be a pH which would allow the weak acid to fully ...
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Which is more acidic : 2,6- dihydroxy benzoic acid or 2-hydroxy benzoic acid?
This post address the acidity of ortho and para hydroxy benzoic acid. However, what effect is there if there are two hydroxy groups ortho to carboxylic group?
I know hydrogen bonding is also at work ...
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How do salts affect pH? [closed]
Since pH measures the effective proton concentration, it is the concentration of a very specific type of cation. I know if salt reacts with water, it will affect pH. But my question is, how does the ...
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Is it appropriate to call an element an amphoteric substance?
In most of Japanese high-school textbook it is written that Al,Zn,Sn and Pb are amphoteric element(in Japanese 両性元素）because they react both with strong acid and base.
For example Al reacts like below.
...
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Intense purple colour of litmus paper in contact with calcium oxide
When conducting an experiment to identify some common chemicals, I tested
crystal/powder samples of the chemicals with moist litmus paper. When I put a piece of blue paper on some $\ce{CaO}$ powder, ...
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What do you think is happening to aluminium in salt water with rusted copper?
I put some aluminium foil and rusted copper(namely a Japanese 10 yen coin) in saturated NaCl solution.
After some minutes tiny amount of small bubbles were observed on the surface of the foil.
After ...
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Reaction of hydrogen peroxide with acetic acid and potassium permanganate
I conducted an experiment where I mixed hydrogen peroxide $\ce{H2O2}$, acetic acid $\ce{CH3COOH}$ and potassium permanganate $\ce{KMnO4}$ under vigorous stirring. The reaction hasn't stopped after 15 ...
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Can I use a mechanical pipette to transfer strong acid?
I am an undergraduate student majoring in physics. I am looking for the best method to accurately measure the volume of strong acids like hydrobromic $(w(\ce{HBr(aq)}) = 48\,\%)$ and hydroiodic $(w(\...
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Does the acidity constant depend on the solvent?
Today I came across $pK_a$ values that depend on the solvent. For the hypothetical reaction $HA \rightarrow H^+ + A^-$, I had in mind that the acidity constant is defined simply as $K_a = \frac{\{H^+\}...
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How do clay particles form a colloidal mixture?
I have been learning about water coagulation in my chemistry textbook. Apparently, before being treated, water has clay particles, primarily silicates and aluminosilicates, which apparently have a ...
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Why can water act as a base under acidic conditions in organic chemistry mechanisms?
In Organic Chemistry mechanisms, I've commonly seen water getting protonated to complete a mechanism, and I'm getting a bit confused on how water can easily get protonated.
From the autoionization of ...
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Dissociation of Water?
My teacher told me that 1 in 553 million water molecules dissociate.
However, since water has a pH of 7, shouldn’t 1 in every 10,000,000 water molecules dissociate?
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Why and how do aqueous silica systems precipitate and can its occurrence be mitigated by quantifying its speciation correctly?
Background/Context:
For context, I have been doing a lot of work on experimental systems in geopolymer chemistry lately with a focus on "activator" solutions which are essentially mixtures ...
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