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).

Filter by
Sorted by
Tagged with
6
votes
2answers
12k views

Alkalis and Bases

I just learnt about acids and bases at class.I noticed that my textbook mentions the term "alkali/alkaline" and sometimes it mentions "base/basic". As far as I know, alkalis and bases are metal oxides ...
6
votes
2answers
70k views

Why does the hydroxide ion have a negative charge?

I've been studying the roles of hydroxide & hydronium in acids and bases, and it was mentioned that a hydroxide ion (OH-) has a negative charge. Can someone give me a layman's explanation of what ...
6
votes
1answer
33k views

How to identify a redox reaction?

Which balanced equation represents a redox reaction? \begin{align} &\mathrm{A.} &\ce{AgNO3 + NaCl &-> AgCl + NaNO3} \\ &\mathrm{B.} &\ce{BaCl2 + K2CO3 &-> BaCO3 + 2KCl} ...
6
votes
2answers
475 views

Can hydroxides ionize alcohols?

For example, can $\ce{NaOH}$ ionize ethanol into ethoxide? My textbook (Organic Chemistry, 6th edition, by M. Loudon and J. Parise, Roberts & Company 2016) suggests yes — it uses it in its ...
6
votes
1answer
9k views

Why, in titration, is universal indicator not commonly used?

My teacher said that we always used indicators such as methyl red, methyl orange, litmus, phenolphthalein, etc. rather than universal indicator. I don't understand why, though, would not universal ...
6
votes
3answers
28k views

Is magnesium sulfate basic, neutral or acidic?

A question in my college test was whether $\ce{MgSO4}$ is neutral, acidic or basic. I was told to solve this kind of problem by hydrolyzing any ions that do not "come from" a strong acid or a strong ...
6
votes
1answer
512 views

Why is dimethyloxonium cation stronger acid than hydronium?

$\ce{(CH_3)_2O^+ H}$ has $\rm pK_a \; -3.8$ while $\ce{H_3O^+}$ has $\rm pK_a \; 1.74\;.$ So, the former is stronger acid than latter hydronium ion. But why is it so? Is it due to the $\rm +I$-...
6
votes
3answers
41k views

How to rationalise that when we dilute a weak acid, the pH increases but also the dissociation increases?

When water is added to a weak acid like ethanoic acid, the number of ethanoic acid molecules that dissociate increases, however, pH increases (less acidic), too. Why is this so?
6
votes
1answer
10k views

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?
6
votes
2answers
1k views

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 ...
6
votes
2answers
16k views

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+]}}{...
6
votes
2answers
1k views

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 ...
6
votes
2answers
15k views

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\ \...
6
votes
3answers
2k views

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 ...
6
votes
1answer
11k views

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{...
6
votes
3answers
4k views

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 ...
6
votes
1answer
2k views

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 ...
6
votes
2answers
11k views

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 ...
6
votes
3answers
3k views

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 ...
6
votes
2answers
322 views

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 ...
6
votes
1answer
2k views

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 ...
6
votes
3answers
2k views

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 ...
6
votes
1answer
4k views

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 ...
6
votes
1answer
4k views

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 ...
6
votes
1answer
4k views

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 ...
6
votes
1answer
3k views

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 ...
6
votes
3answers
3k views

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 ...
6
votes
2answers
3k views

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_\...
6
votes
3answers
2k views

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 ...
6
votes
1answer
540 views

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 ...
6
votes
1answer
1k views

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 ...
6
votes
3answers
3k views

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: $$...
6
votes
1answer
1k views

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 ...
6
votes
1answer
5k views

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 ...
6
votes
3answers
595 views

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 ...
6
votes
1answer
4k views

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 ...
6
votes
2answers
20k views

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 ...
6
votes
2answers
911 views

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, ...
6
votes
1answer
125 views

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?
6
votes
2answers
963 views

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 $8.1$...
6
votes
2answers
212 views

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 ...
6
votes
3answers
1k views

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 ...
6
votes
2answers
6k views

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 ...
6
votes
2answers
3k views

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 ...
6
votes
2answers
657 views

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 ...
6
votes
2answers
8k views

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, ...
6
votes
3answers
368 views

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-}...
6
votes
1answer
134 views

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}}...
6
votes
1answer
487 views

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 ...
6
votes
2answers
1k views

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: $$\ce{9S + 4NaOH -> 2Na2S4 + SO3 + H2O}$$

1 5 6 7 8 9 49