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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Pipetting strong acid with plastic material

Can I pipette concentrated sulfuric acid using a plastic pipette tip? Will either the plastic or the acid be affected?
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Comparison of acids to dissolve phosphates

I am currently reading this German paper on the dissolution of phosphates by acids and chelants. The authors do a "fast-test" of the dissolving power of different acids which goes as follows: For ...
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Why does gaseous HCl not change dry blue litmus paper to red?

I am doing a practical in lab, in which HCl is to be evolved. I found that when blue litmus is near the evolved gas, it doesn't turn red. But, when litmus is dipped in water and then brought near the ...
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Why is water not part of the equilibrium constant?

In the acid base reaction $$\ce{NH4+ + H2O <-> NH3 + H3O+}$$ the acidity constant, which is a relation between concentrations is given by $$K_{\mathrm{a}}=\frac {\ce{[NH3]} \cdot \ce{[H3O+]}}{...
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Odd Acidity Trend in Hexaaqua Metal Complexes

In the following link (three quarters down the page) it states that theoretically there should be a proportional relationship between the ionic radius and pKa of a hexaaqua metal complex (provided ...
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pH of dilute HCl solution

What is the pH of a solution of $3.4 \times 10^{-10}$ moles of $\ce{HCl}$ in a volume of $\pu{150.7L}$? This is dilute so I expect pH to be high. $$\frac{3.4 \times 10^{-10}\ \mathrm{mol}}{150.7\ \...
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The nomenclature of mineral acids

My basic knowledge about nomenclature is: A mineral acid is called hypo when it has one less oxygen than the original one, a pyro acid when 2 molecules of acid add up with release of $\ce{H2O}$ a ...
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Why is carbon monoxide a neutral oxide?

Carbon monoxide ($\ce{CO}$) is considered to be a neutral oxide, not acidic or basic. But why? It reacts with hot concentrated sodium hydroxide solution to give a solution of sodium methanoate: $$\ce{...
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Aqua regia and nascent chlorine

Aqua regia has the famous property of being able to dissolve noble metals, like gold and silver. I read that this has to do with the generation of nascent chlorine. How does this happen and how does ...
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Why alcohols don't behave as acids?

If I understand everything correctly, carboxylic acids behave like acids because oxygen is much more electronegative than hydrogen, so it takes his electron and releases H+. The problem is that ...
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Calculating pH of diprotic and amphoteric solutions

I am trying to understand this problem and its corresponding solution (complete solution not shown) First off, from the above one can see that the equilibrium constants when $\ce{H2ASO4-}$ donates ...
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How can I measure the pH of high-viscosity fluids like dough?

I would like to measure the pH value of dough with a pH-Meter, to ensure a pH value of 4.1 (max). Because of the high viscosity I would thin down the dough with demineralized water for two reasons: I ...
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How are neutral amines effective bases in organic chemistry?

I have found it to be rather strange that neutral amines, such as triethylamine or DIPEA, find applications in organic chemistry in deprotonating alcohols or even α-carbonyl compounds. Amines are ...
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Which is the strongest base?

When I was in lower grades, I was taught $\ce{NaOH and KOH}$ are the strongest bases. But I realised later that there can be more stronger ones. After a bit of research on the internet, I found these ...
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If I mix carbon dioxide and sodium hydroxide in the right amounts in water, do I get baking soda?

Suppose I need a sodium bicarbonate solution (for non-food related reasons). Can I get something resembling it by mixing $\ce{NaOH}$ and $\ce{CO2}$ in water? Of course one should not attempt to make ...
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How to calculate pH of a solution when H3PO4, NaH2PO4, Na2HPO4 and Na3PO4 are mixed together in certain amounts to form a solution?

How to calculate pH of a solution when $\ce{H3PO4}$, $\ce{NaH2PO4}$, $\ce{Na2HPO4}$ and $\ce{Na3PO4}$ are mixed together in certain amounts to form a solution? I know how to calculate pH when they ...
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What is the difference between a reaction of Lewis acids with Lewis bases and a redox reaction?

For example I came across this equation: $\ce{2Al_{(s)} + 6HCl_{(aq)}} \longrightarrow \ce{2Al^{3+}_{(aq)} + 6Cl^{-}_{(aq)} + 3H_2_{(g)}}$ And thought this was a redox reaction but my book says it ...
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Why does ammonium carbonate smell?

Why is it that $\ce{(NH4)2CO3}$ smells while other salts with ammonium like $\ce{NH4Cl}$ does not smell? Does it have something to do with the equilibrium reaction? I know it has nothing to do with ...
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Can aluminum and hydrochloric acid be used to generate hydrogen gas?

I am looking to produce hydrogen gas in a small amount with supplies I currently have. Most of the methods I have seen involve reacting zinc or magnesium with $\ce{HCl}$ to obtain the gas, but I do ...
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Why is propanoic acid weaker than butanoic acid?

I was reading about electronic effects in organic compounds, and I found the explanation that carboxylic acids are weakening as their number of carbon atoms increase. But I found a table of $K_\...
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Why should 2,6-Dimethyl-4-nitrophenol be more acidic than 3,5-Dimethyl-4-nitrophenol

I was trying to compare acidity of some organic compounds but can't understand some: Why should 2,6-dimethyl-4-nitrophenol be more acidic than 3,5-dimethyl-4-nitrophenol? I have been trying to ...
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Why does chlorine undergo disproportionation in alkaline media?

One reaction used to form sodium hypochlorite (A type of bleach) is as follows: $\ce{2NaOH(aq) +Cl2(g)->NaOCl(aq) + NaCl(aq) + H2O(l)}$ Provided the sodium hydroxide is dissolved in some ...
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How useful is the assumption that water doesn't auto-ionize in the following?

Now in the first row of the iCe-table, $[\ce{H3O+}]$ is said to be 0. But water autoionizes to some extent, so it shouldn't really be 0. I accept that, because the pH of this solution is 2.5, the ...
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Why does adding salt to water reduce the pH?

I recently heard someone claim that adding table salt to vinegar caused HCl to form which helped them clean coins - clearly not the case - however I thought I'd disprove it by doing an experiment. So ...
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Why is the compound 3,4-dihydroxy-3-cyclobutene-1,2-dione more acidic than acetic acid?

Why is the compound 3,4-dihydroxy-3-cyclobutene-1,2-dione more acidic than acetic acid? I don't get how its resonance stabilization is far greater than that of acetic acid despite the fact that the ...
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Why can't primary alcohols react with sodium bromide via an SN2 mechanism?

I was told that a primary alcohol reacts with $\ce{HBr}$ for example, but not with $\ce{NaBr}$ through the $\mathrm{S_N2}$ mechanism in the same reaction environment. Why? This reaction can occur: $$...
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Water reacts or doesn't react?

I know that when you have $\ce{HCl}$, $\ce{H2O}$, and $\ce{NaOH}$ that you produce $\ce{H2O}$ and $\ce{NaCl}$. However some people say water does react and so would think that this 2 step reaction is ...
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Do weak acid/weak base neutralisation reactions go to completion?

I'm wondering if reactions that involve a weak acid and a weak base go to completion. For example, say we have equal amounts and equal volumes of acetic acid and ammonia being mixed together. Would ...
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The effect of NaCl on the ability of an acid to protonate benzoate

I've been doing several experiments using soda to quantify the amounts of caffeine and benzoate. Because of our methods of analysis, we had to decarbonate our soda. The experiment offered two ways for ...
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Citric acid chelates calcium carbonate more than ethanoic acid, why does this result in a faster rate of reaction?

I performed an experiment using egg shells (calcium carbonate) to represent teeth and reacted the calcium carbonate with acids. When measuring the rate of reaction citric acid had a higher rate of ...
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MgCl2 acidic or neutral in water?

I'm currently taking chemistry 12. On our test we were asked, when given a $0.1~\mathrm{M}$ solution of certain compounds whether the resulting solution when added to water would be acidic, basic, or ...
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How to assess the strength of the acid?

Which is the stronger acid in the given pairs? $\ce{HClO3}$ and $\ce{HBrO3}$ $\ce{HClO2}$ and $\ce{HClO}$ $\ce{H2Se}$ and $\ce{H2S}$ given that the number of oxygen atoms is the same, ...
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How can I- be both a nucleophile and a weak base?

I am just confused as to how $\ce{I-}$ cannot attract $\ce{H+}$, but it can attack a carbocation. It is sharing electrons in both cases, so what is the difference?
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How to calculate the concentration of conjugate acid from given pH and pKa values?

Preface: Buffer solution (acid-base buffer). I am provided with a weak base, which I will designate B. $\mathrm{p}K_\mathrm{a}$ for $\ce{B}$'s conjugate acid, which I will designate $\ce{BH}$, is $8.1$...
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Why is aluminium(III) considered a hard acid if it forms covalently bonded compounds like aluminium oxide?

If something is a hard acid, it tends to form ionic bonds as it is polarizing. So why is the aluminium ion a hard acid when it forms bonds with covalent character. A similar argument follows for why ...
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Could neutralisation of safe chemicals produce dangerous ones?

I'm basically thinking whether I could potentionally poison myself while neutralising strong acid/base by some weak base/acid when I accidentally spill it, touch it or when I'm cleaning reaction ...
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Why is it that neither silver nor copper react with a strong acid?

$\ce{Fe}$, $\ce{Mg}$, $\ce{Ni}$, $\ce{Pb}$, $\ce{Sn}$, and $\ce{Zn}$ all react when they (in solid form) are submerged in an acid solution with the presence of a strong acid like $\ce{HCl}$, but ...
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Why is ortho-hydroxybenzoic acid more acidic than its para-isomer?

Why is ortho-hydroxybenzoic acid $(\mathrm{p}K_\mathrm{a} = 2.98)$ more acidic than its para-isomer $(\mathrm{p}K_\mathrm{a} = 4.58)$? March's Advanced Organic Chemistry (7th ed) gives the reason to ...
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Stabilisation of anions by silicon

In my lecture notes it was stated that in $\ce{Me3SiCH2SMe}$, deprotonation with tBuLi generates an anion in between Si and S. I've been not able to find the $\mathrm pK_\mathrm a$ values (not listed ...
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What is causing the buffer region in a weak acid - strong base titration?

For the buffer region in this, why does it stop the pH from increasing? At the start: $$\ce{CH3COOH + NaOH -> CH3COONa + H2O}$$ Which means there will be a high amount of salt in the solution, ...
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Why is the ionic product of water not divided by the concentration of water?

I know the ionic product of water is $[\ce{H+}][\ce{OH-}]$, by following the equation: $$\ce{H2O <=> H+ + OH-}$$ But actually it's just another way of writing: $$\ce{2H2O <=> H3O+ + OH-}...
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Deriving the buffer formula

Essentially I want to derive the buffer formula: $\ce{pH}$ = $\mathrm{p}K_\mathrm {a}$ + $\log$ $\left(\frac{\alpha}{1-\alpha} \right)$ to $\alpha$ = $\left(\frac{1}{10^{\mathrm{p}K_\mathrm{a}-\ce{pH}}...
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What alcohol concentration makes bathroom cleaner “disinfecting”?

There are many do-it-yourself cleaner solutions out there, using a combination of vinegar, alcohol (in a "cheap vodka" concentration), dish soap, baking soda and essential oils. I like these recipes ...
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Sodium Polysulfide production from NaOH and Sulfur

Does the sulfur also oxidize the $\ce{OH-}$ radicals after the $\ce{Na2S4}$ chains form? Something like this: $$\ce{9S + 4NaOH -> 2Na2S4 + SO3 + H2O}$$
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steam distillation of 4-bromoaniline , why render it basic prior

In the multistage synthesis of 4-bromobenzenamine, why must the solution be rendered alkaline prior to the steam distillation after the hydrolysis of 4-bromo-N-ethanoylbenzenamine?
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Is the Ocean acidification inconsistent with the Bjerrum plot?

$\ce{CO2}$ dissolves in water and goes through chemical reactions and exists at different concentrations of, dissolved $\ce{CO2}$, carbonic acid, bicarbonate, and carbonate. The Bjerrum plot ...
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Effect of dillution on titration

When we are titrating acid/base using ph meter we add distilled water to immerse the ph electrode. Won't this affect the concentration of the acid/base: I mean isn't this dillution. Won't this ...
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Why do most carboxylic acids have high pKa (~5) in spite of having a conjugate base ion that is stabilized by resonance?

This is from my textbook: Carboxylic acids owe their acidity ($\mathrm pK_\mathrm a$ of about $5$) to the resonance-stabilized carboxylate anions formed by deprotonation. Why are they such weak ...
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How are Grignard reagents stable in an ethereal solution? [duplicate]

I have heard of the leveling effect, which mentions that highly basic ions cannot exist in a solvent if it's acidity is high enough to be deprotonated by the base. Considering that, check out the ...
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Buffer formation in weak acid/strong base titration?

I'm a little confused about what happens when you titrate a weak acid or base. For example, let's say that you are trying to titrate a weak acid. Based on this question, it seems like the weak acid ...