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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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66 views

Could a strong acid become a strong base? [closed]

Is it technically possible for a strong acid to change into a strong base, through a chemical reaction? Example: if an acid with pH 1 became a base with pH 12.
0
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1answer
314 views

Would the End Point and Equivalence Point be Labelled the Same?

I created two graphs of two different titrations : One graph was the titration curve of acetic acid with sodium hydroxide (weak acid-strong base) and the other was that of nitric acid with sodium ...
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1answer
46 views

Dealkalization of water

I want to remove Alkalinity from tap water by using an acid. The starting point is about 370pm alkalinity, and I am wondering to reduce this to about 50ppm, could I use a weak acid like citric acid? ...
3
votes
1answer
32 views

What changes occur when adding differing amounts of acids & bases?

In an experiment, $\pu{5 cm^3}$ of $\pu{1 mol/dm^3}$ sodium hydroxide are gradually added to $\pu{10 cm^3}$ of $\pu{1 mol/dm^3}$ hydrochloric acid containing methyl orange. What changes occur in the ...
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1answer
53 views

Metal phosphate buffers [closed]

A calibration solution contains $\pu{0.02M}$ $\ce{Cr^3+}$ and $\pu{0.02M}$ $\ce{Cu^2+}$. In order to control the solution $\mathrm{pH} = 12$, a phosphate buffer is used with the weak acid being $\ce{...
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0answers
39 views

Acyl Chloride + Water reaction

A part of the mechanism between ethanoyl chloride and water is shown above. Now, I know that this reaction produces fumes of HCl as the HCl gas reacts with moisture in air, but does it also produce ...
7
votes
1answer
82 views

Why does ammonia accept a hydrogen to form ammonium when its octet is already complete?

Why does ammonia accept a hydrogen to form ammonium when its octet is already complete as $\ce{NH3}$ and it should be, seemingly, stable as $\ce{NH3}$?
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1answer
134 views

When calculating enthalpy changes of reaction using, why is only the number of moles of one reactant used?

When calculating the thermal energy released during an acid-base neutralisation using the equation $Q = mc\Delta T$, and then using $\Delta H = - Q/n$ to calculate the enthalpy change of ...
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0answers
435 views

Calculating the pH of a solution of sodium carbonate

I've seen similar questions on this site, but I'm having trouble as my book said something else. For a $\pu{0.09989 M}$ solution of $\ce{Na2CO3}$, my book said: $$\ce{Na2CO3 + 2H2O -> H2CO3 + 2Na+ ...
1
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1answer
80 views

Approximated formula of acid dissociation constant

$K_\mathrm{a}$ can be expressed as $K_{\mathrm{a}} = \frac{[\ce{H^{+}}] [\ce{A^-}]} {[\ce{HA}]}$, however, it can be approximated that $K_{\mathrm{a}} = \frac{[\ce{H^{+}}]^{2}} {[\ce{HA}]}$. I ...
3
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1answer
316 views

Which would be more acidic, benzene or cyclohexane?

If benzene were to donate a hydrogen ion, then could the negative charge still be delocalised around the ring? Wouldn't that break aromaticity and thus destabilise the molecule?
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2answers
102 views

What is the ionization constant, $K_a$, of the acid?

A 0.45 M solution of a weak acid, HX, has a pH of 4.5. What is the ionization constant, $K_a$, of the acid? Attempt at solution: [HX] is already given as 0.45 M. [H+] is given by $10^{-4.5}$. ...
0
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1answer
134 views

What is the citric acid concentration, [HCit], in the lemon juice?

The pH of lemon juice is about 2.1. What is the citric acid concentration, [HCit], in the lemon juice? I am given that $HCit \leftarrow \rightarrow H^+ + Cit^-$ and that $K_a = 8.4 \times 10^{-4}$. ...
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votes
2answers
112 views

calculating pH - is my answer correct?

I'am working on this exercice, Is my answer correct? and can you please help me to solve the second part? exercice: 1/Calculate the ionization coefficient and pH (with two methods) of a 0.1M ...
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0answers
204 views

Does negative pH mean it is a stronger acid than one with positive pH?

I've searched this site but I don't think this has been asked yet. Does negative pH indicate a stronger acid than a positive pH (since it's further down the scale)? I'm asking this because in one of ...
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1answer
979 views

Calculating the pH upon titrating barium hydroxide and hydrochloric acid

Question: Calculate the pH produced from mixing $\pu{25.0 mL}$ of $\pu{0.420 M} $ $\ce{Ba(OH)_2}$ with $\pu{125 mL}$ of $\pu{0.120 M}$ $\ce{ HCl}$. Attempt: I'm learning about acids and bases ...
2
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0answers
34 views

Are anions stronger bases than (different) neutral molecules?

I need to compare the basicity of 2 molecules: a negatively charged $\ce{O}$ attached to a t-butyl (t-butoxide), and a neutral $\ce{N}$ with 3 ethyls attached to it (triethylamine). These are ...
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3answers
2k views

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. ...
3
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1answer
110 views

Reaction of carbonyl cyclic diene with Grignard reagent

Predict the major product of this reaction: The two compounds on the right are the possibilities that I thought of (weren't given in the question). According to me: attack on carbonyl carbon ...
-2
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1answer
401 views

Is the relationship between Ka and Kb the same for all acid base pairs? [closed]

What is the relationship between $K_\mathrm{a}$ and $K_\mathrm{b}$ for acid/base reactions. I know for water $K_\mathrm{w}=K_\mathrm{a}\cdot K_\mathrm{b}$, where $K_\mathrm{w}$ is $10^{-14}$. Is this ...
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1answer
150 views

How would a pH curve look like for titration of diluted weak base compared to concentrated one?

Let's say I take $\pu{80 g}$ of a weak base, dilute it with $\pu{50 ml}$ of water and titrate it with a strong acid. I get a titration curve. Now I take again $\pu{80 g}$ of the same weak base but ...
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1answer
39 views

Getting from pH 2 to pH 6 by mixing with water

In our book we learned that we can get an acid to a higher $\mathrm{pH}$ by mixing it with water in the relation $\frac {1}{10} $. Now to my problem: How much water do you need in order to get the $\...
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0answers
44 views

Is endpoint pH concentration dependent? Choosing an acid/base indicator

We use titrations to determine analyte concentrations with a standardized titrant and an acid/base indicator, BUT how do we choose the indicator? It is my understanding that indicators are supposed to ...
5
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1answer
112 views

Why does my sodium acetate look like metalic magma?

I tried to make sodium acetate. Ingredients: Store bought vinegar - 8% acetic acid, water, E150C (caramel) Baking soda - $\ce{NaHCO_3}$ Steps: I first emptied sacks of baking soda to a ...
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0answers
119 views

How to remove/dissolve thick black iron oxide

I have an exhaust manifold from a boat I recently purchased which has not been looked after (left with sea water in/silt and mud deposits in it etc). I have been trying to clean out the manifold but ...
0
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0answers
79 views

How much sodium hydroxide powder do I need to add to get a new pH?

I want to increase the pH of a $\pu{300 ml}$ deionised water solution from 7 to 11. How much sodium hydroxide should I add? I have tried this but the answer doesn't seem correct (because it's so small)...
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2answers
81 views

Buffer Solution Problem (Acid/Conjugate Base)

To create a buffer mixture, I understand that mixing an equal concentration of a weak acid and it's salt (conjugate base) will form an acidic buffer. However, why is it that when $\pu{25 cm^3, 9.100 ...
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0answers
91 views

unambiguous rule for determining conjugate acids and conjugate bases such that conjA(conjB(X))=X?

Is there a set of rules for determining a substance's "conjugate acid" and a substance's "conjugate base", such that: the rules give you an absolutely unambiguous answer as to "What is the conjugate ...
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1answer
81 views

Picric Acid from Salicylic Acid

When Salicylic Acid is nitrated, the end $\ce{COOH}$ group is getting knocked out. How should I reason the knocking. Is it right to say, since $\ce{HCOOH}$ is more acidic than $\ce{HOH}$, hence, $\ce{...
3
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1answer
236 views

Why is ethanoic acid more acidic than phthalimide?

Why is ethanoic acid more acidic than phthalimide? $\mathrm{p}K_\mathrm{a}$ of phthalimide is 8.3 (source), while that of ethanoic acid is 4.76 (source). Applying the logic found here would suggest ...
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1answer
54 views

How does bismuth's lone pair affect its properties as a metal and alloy?

Bismuth is really the only metal to exhibit a lone pair in its outermost shell, this means that it and its salts should be a Lewis base. As bismuth can act as a Lewis base, how does this affect its ...
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1answer
36 views

What is the reaction mechanism between a basic oxide and an acid?

For instance in $$\ce{ Li2O (s) + 2HCl (aq) -> 2LiCl (aq) + H2O (l)}$$ I am wondering why the $\ce{Cl}$ displaces $\ce{Li}$ .I figure that oxygen is negatively charged as it pulls the electron from ...
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1answer
387 views

Zinc in a single displacement reaction with hydrochloric acid [closed]

I understand that on the metal activity series, zinc can displace hydrogen from acids, but not from cold water. But is there a structural reason for this. For example, why can zinc displace hydrogen ...
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1answer
52 views

Confusion about the ICE table

Calculate the pH of a $\pu{2M}$ $\ce{H_3PO_4}$.Calculate the equilibrium concentrations of $\ce{H_3PO_4 , H_2PO_4^{-} , HPO_4^{2-}}$. First equation: $\ce{H_3PO_4 <=> H^{+} + H_2PO_4^{-}}\ \ \...
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0answers
644 views

Calculate pH at equivalence point given one concentration

Question: What would the pH be at equivalence if oxalic acid is titrated with $\pu{0.10 M}$ $\ce{NaOH}$? Attempt: I tried doing the problem, but felt like it was missing details. Wouldn't I need ...
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1answer
552 views

Calcium carbonate and hydrochloric acid

I am trying to solve an exercise, where a block of 605.5g calcium carbonate should be completely dissolved in 30% hydrochloric acid (w/w) and the concentration of the acid should be 3% in the end. The ...
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0answers
52 views

Relative concentrations of ions in acid-base reaction

An aqueous solution of ammonia has of pH = x, and a solution of hydrochloric acid has pH =y; it is also known that x + y = 14, and x > 11. If equal volumes of these two solutions are mixed together, ...
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0answers
96 views

HCl + fingernail (set for a year) + H2O2 + Cu [closed]

I had a $\ce{HCl}$ in a container which a year ago a fingernail fell into it there were no way for me to remove it. The result of $\ce{HCl}$ and that fingernail is some brownish solution as shown: ...
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0answers
41 views

How does sodium hydroxide dissolve flesh? [duplicate]

How does sodium hydroxide or bases dissolve flesh? I want to know mechanisms how sodium hydroxide dissolves our body protein.(or other organnic matters) Thank you in advance.
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2answers
222 views

How to make a pH 6.8 Tris buffer?

To preface this, I am a biologist. I need to make a $\mathrm{pH}=6.8$, $\pu{1 M}$ Tris buffer. We have access to Tris base and Tris Hydrochloride. (Unfortunately, none of the fancy Tris compounds ...
18
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2answers
2k views

What are the crystals that have formed around the top of a conc. nitric acid bottle?

I was looking through my chemicals cupboard and found that this decades-old bottle of conc nitric acid had grown a beard. I can't think of any reaction between (presumably) $\ce{NO2}$ and any airborne ...
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3answers
344 views

Can strong acids be amphoteric?

There are amphiprotic (or amphoteric) substances, like $\ce{H2O}$ and $\ce {HCO3-}$, which act both as an acid and base. If you mix a strong acid like $\ce{HCl}$ ($\mathrm{p}K_{\mathrm{a}} = -6.3$) ...
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1answer
101 views

How to justify this contradiction in acid-base equilibrium of methanol and water? [duplicate]

Let's talk about the following compounds - water and methanol. We know that methanol is slightly more acidic than water, because water's ability to donate a proton as an acid is reduced due to ...
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1answer
51 views

Calculation of composition of drain cleaner

Important note: I'm an eighth-grader. I taught myself chemistry to organic chem using an arsenal of textbooks*, but I have gotten things wrong, namely resonance. Please read above (also this if you ...
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1answer
3k views

Mixing hydrochloric acid and sulphuric acid, both concentrated

In the chemistry lab, I stupidly decided to mix hydrochloric acid and sulphuric acid, both concentrated, in a random ratio, which was about $\pu{50 ml}$. When I poured them in one test tube, the ...
9
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0answers
138 views

Protonating/basic site and Brønsted basicity orders of beta, gamma, and delta lactams

Consider the three cyclic amides: $\beta$-lactam $\gamma$-lactam $\delta$-lactam My question What is the basic site (site of protonation) for these three lactams? And what should be their Brønsted ...
7
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1answer
1k 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 ...
4
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0answers
80 views

Can Hydronium Act as a Ligand?

Can hydronium function as a ligand? For instance could there exist $\ce{[Al(H3O)4]^{+7}}$ or $\ce{[Fe(H3O)6]^{+9}}$ cations? I asked my chemistry teacher and he said that he's never encountered a ...
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0answers
29 views

Removing chloride ions from humic acid purification

I used HF and HCl in humic acid purification, and now I need to remove the Cl ions from solution. What should I do to remove the Cl ions? Do I just wash it with distilled water, or is there another ...
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2answers
13k views

Why don't we explode after drinking water?

It is known that acid should be added to water and not the opposite because it results in an exothermic reaction. Our stomach contains HCl, so why don't we explode when we drink water?