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 HCl is used in Lucas test?

In Lucas test $\ce{HCl}$ is used for acid-base reaction between $\ce{Zn(OH)Cl}$ to give $\ce{ZnCl2}$ and $\ce{H2O}$ which is kind of good because $\ce{ZnCl2}$ is formed again and used in first step ...
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What can be added to hydrochloric acid to make a gel or paste?

I have a bottle of brick cleaner containing 18-20% hydrochloric acid. What can I add to it to make a gel or paste without unwanted reactions? The application is still just cleaning bricks as the ...
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HNO2 as a lewis acid

I read that $\ce{HNO2}$ is a very unstable compound but I still can’t figure out which atom is the cause of this instability or like what’s the reason? My second question is: For a compound with ...
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Strength of bases and acids

Is it possible that strong acids like $\ce{H2SO4}$ behave as weaker ones like $\ce{CH3COOH}$ when the concentration is really high and vice versa for weak acid? And the same question for bases. By ...
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1answer
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What will be the colour of HCl with methyl orange?

I am new in chemistry and this question can be silly, but I am troubled with this question. According to the pH range of methyl orange, if I add methyl orange into water, it gives a yellow color (pH ...
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How can benzaldehyde have a pKa of 14.9?

There are numerous websites out there which claim that the pKa of benzaldehyde – C6H5CHO – is 14.90. (Just do a Google search for benzaldehyde pka to see what I ...
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27 views

Why basicity decreases for leaving groups, but nucleophicity increases for an overall compound, going down the periodic table?

Basically, I read that nucleophilicity increases going down the periodic table within a particular group, due to polarizability, but basicity decreases down a group (or family) in the periodic table, ...
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Buffer which was prepared by dissolving 0.10 mol of benzoic acid is dissolved [closed]

A pH 4.88 buffer which was prepared by dissolving 0.10 mol of benzoic acid (Ka = 6.3x10-5) and 0.50 mol of sodium benzoate in sufficient pure water to form a 1.00 L solution. A 2.00 mL of 2.00 M HI ...
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What actually happens in strong acid- weak base reactions?

I'm going back through my notes from a chemistry class, which I did well in despite not having a very good conceptual understanding, in order to hopefully develop that understanding, but there's ...
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47 views

Calculating concentration of OH⁻ ions [closed]

Calculate concentration of $\ce{OH-}$ ions in $\pu{0.66 mol L^-1}$ solution of $\ce{NH4+}.$ I think that there might be something missing, as the only law I have for this kind of problems is $$[\ce{...
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172 views

How to determine the purity of lactic acid with titration?

$\pu{25 mL}$ of $\pu{0.5 \%(w/v)}$ lactic acid ($\ce{C3H6O3}$, molecular mass $\pu{90.1 g mol-1}$, $\mathrm{p}K_{\mathrm{a}} = 3.86$ was neutralised by $\pu{13.1 mL}$ of $\pu{0.1010 M}$ monobasic base....
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What happens when C17H35COO-, a soap, reacts with an acidic solution?

My book says that- In acidic water, the negative fatty acid ions become fatty acids. However, they did not include a chemical equation to demonstrate this, so I made my own: $$\ce{C17H35COO- (aq)...
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Why exactly is a fluoride anion a stronger base than iodine anion?

First off, I've learnt that stronger acids produce weaker conjugate bases (through Brønsted–Lowry acid–base theory). Then I looked at the $\mathrm{p}K_\mathrm{a}$ values of $\ce{HF}$, $\ce{HCl}$, $\...
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Find the concentration of the HCl solution when mixed with 1.265g of ACES-K+

$\pu{1.265 g}$ of N-(2-acetamido)-2-aminoethanesulfonic acid potassium salt ($\ce{ACES^-K+}$, $M=\pu{220.29 g/mol}$) is dissolved in $\pu{88.42 mL}$ of water. $\pu{27.59 mL}$ of $\ce{HCl}$ is added to ...
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What is the difference between enthalpy change and energy change? [closed]

This question seems really dumb but I rather be safe than sorry. I read about enthalpy change in my chemistry textbook which defines enthalpy change as the energy exchange between a chemical reaction ...
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1answer
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Does citric acid react with carbonated water?

I've noticed that when adding lemon juice to carbonated water, large 'soapy' bubbles appear on the surface. Since I'm adding another acid to a solution of carbonic acid, I would maybe expect a faster ...
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Is honey a good choice for chemistry senior essay? [closed]

I am doing my senior essay on chemistry and I was interested in honey, the only thing that's scaring me is that my content is more of biology rather than chemistry, in other words, does honey involve ...
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Acid/base stoichiometry exercise [closed]

How much water in moles is produced when excess hydrochloric acid ($\ce{HCl}$) neutralizes 6.2 moles of barium hydroxide ($\ce{Ba(OH)2}$)? Write the balanced chemical equation.
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Acidity order of acetone, methyl acetate and N,N-dimethylacetamide

Why is the acidity order true? $$\ce{CH3COCH3} > \ce{CH3CO2CH3} > \ce{CH3CON(CH3)2}$$ I deduced that in methyl acetate and N,N-dimethylacetamide there is a −I effect of the methoxy group, $\...
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1answer
265 views

Why is maximum buffer capacity for some diprotic buffers not when pH = pKa?

According to Rajkovic et al. [1]: $$β = \frac{[\ce{H+}]}{K_\mathrm{w}} + 2.303\cdot\frac{[\ce{H+}]\cdot K_\mathrm{a}\cdot c}{[\ce{H+}] + K_\mathrm{a}}$$ where $K_\mathrm{a}$ is the ...
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Gold refining using HCl

I am trying to dissolve base metals off of gold plated electronic scrap, and I am using HCl to dissolve some of the base metals. I pored in the HCl into a flask containing the scrap ( the contents of ...
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Will oxalic acid react with ethanol?

Will oxalic acid, in a saturated solution in ethanol, be able to undergo an esterification reaction with the ethanol? This is assuming no acidifying agents (or anything else, for that matter) are ...
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Out of 3 acids which would react [duplicate]

If I had a product that contained Hydrochloric phosphoric and hydrofluoric acidenter image description here and reacted those acids with zinc without the presence of H2O2 what would my final product ...
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61 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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When does nucleophilic attack and proton transfer happen? [closed]

from the reaction, the 3rd molecule (carboxylic acid) formed undergo neutralization with OH- (proton transfer to a base). However, is it possible for the 3rd molecule to behave as the 1st molecule (...
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4k views

How to Determine Acid Strength?

The correct answer is E But I do not understand why? Shouldn't (v) have the lowest $\mathrm{p}K_\mathrm{a}$ since it does not have a carboxyl group making it a strong acid? How do we determine the ...
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522 views

A defining feature for acids / bases

I know of 3 different definitions for acids and bases including Arrhenius, Brønsted–Lowry and Lewis. Can anyone tell me what is the common feature among these 3, that we have to label the compounds ...
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1answer
63 views

Acidity order of xenon fluorides,oxides and oxofluorides [closed]

The acidity order of xenon oxides,fluorides and oxofluorides is: $\ce{XeF6 > XeO2F4 > XeO3F2 > XeO4 > XeOF4 > XeF4 > XeO2F2 > XeF3 > XeO3}$. How to justify this order? My ...
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36 views

How to know whether a molecule is 'stabilized' [closed]

According to a reference book, in acid-base reactions, the position of equilibrium is shifted towards when the conjugate base is more 'stable' and the relative stabilities are compared by different ...
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1answer
38 views

Reaction of hydrogen peroxide with sodium carbonate [closed]

In my book the following acid base reaction is written: $$\ce{H2O2 + Na2CO3 -> Na2O2 + H2O + CO2}$$ But I found that the $\mathrm{p}K_\mathrm{a}$ value of $\ce{H2CO3}$ is less than the one for $\...
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Find the pH of an amphiprotic salt dissolved in water at room temperature

Let's say I have a polyprotic acid $\ce{H2A}$ with the following properties: $$ \begin{align} \ce{H2A &<=> HA- + H+} & K_1 &= 1\cdot 10^{-1}\\ \ce{HA- &<=> A^2-+ H+} & ...
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Tap water pH adjustment using citric acid

I've lowered tap water pH from 7 to 6 using citric acid. After couple of hours pH raised again to 7. What is the reason for this raise? Citric acid overcomes waters buffering feature then raise the $...
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Why is magnesium sulfate acidic? Why are my calculations showing that it is basic?

Let's say I was dissolving $\pu{1M}~\ce{MgSO_4}$ into water and I wanted to find the pH. I would go right to the reaction of the dissociation of $\ce{Mg(OH)_2}$: $$\ce{Mg(OH)_2 <=> Mg^2+ + 2OH-}...
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In aminobenzoic acid, do we have three different pKa's?

In para-aminobenzoic acid, how can I know whether the amino group loses a proton or not when $\mathrm{pH}$ exceeds $8.5$? I have only found two values for $\mathrm{p}K_\mathrm{a}$ but I never found ...
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How to derive composite acidity constant for H2CO3*?

I see the equation (19) and (20) on Stumm and Morgan's Aquatic Chemistry book (Fig. 1 here). They said "a combination of equations 19 and 20" gives Equation 21. But I don't know how the Equation (21) ...
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37 views

1.0 g of AlCl3 is added to 100.0 ml of water. What would be the resulting pH?

$1.0\ \mathrm g$ of $\ce{AlCl3}$ is added to $100.0\ \mathrm{ml}$ of water. What would be the resulting pH? I think the answer may be $4.022$ but I'm not certain. The reaction wasn't provided but I ...
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How to properly clean spilled battery content?

I was cleaning my wardrobe when I found some huge white-brown blots where there was a lot of batteries that I have use. I was keeping them for properly disposal but I forget to do that. I ...
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Boron trihalides acidity

A boron trihalide ($\ce {BX3}$) is a Lewis acid, because it can accept an electron pair, as per Gilbert N. Lewis' definition. Now my question is- Arrange $\ce {BF3}$, $\ce {BCl3}$, $\ce {BBr3}$ ...
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Dissociation of benzoic acid

Benzoic acid is a weak acid, so it does not completely dissociate in water. I know that the dissociation equation of benzoic acid is: $$\ce{C6H5CO2H <=> H+ + C6H5CO2-}$$ The question I'm ...
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Finding the pH among HF and KOH

Okay I ran into this question in homework. A 100.0 ml sample of 0.20M HF is titrated with 0.10 M KOH. Determine the pH of the solution after adding 200 ml of KOH. The Ka of HF is 3.5 x 10-4? Oh yeah ...
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85 views

Why is HCl the acid of choice for swimming pools?

Why is muriatic acid the go to acid to put into pools? Does it work better than nitric acid, sulfuric acid, or another strong acid? I mean they all will add the same amount of H+ right? Note, we use ...
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188 views

Effect of phenyl and vinyl substituents on Acidity of carboxylic

Recently I came across this statement in my textbook: Direct attachment of groups such as phenyl or vinyl to the carboxylic acid, increases the acidity of corresponding carboxylic acid contrary ...
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Acidic strength of para substituted benzoic acids

Comparing the acidic strength, the nitro-substituted group is definitely more acidic. This can be reasoned by fact that a higher delta positive charge which develops on the H due to the strong -M ...
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How to calculate the concentration of all relevant species in a buffer of a given pH?

You prepare $1.0~\mathrm{L}$ of a $0.25~\mathrm{M}$ acetic acid solution with a final $\ce{pH}$ of $6.0$. What are the molar concentrations of all relevant acetic acid species ($[\ce{HA}]$ and $[\ce{A-...
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1answer
161 views

Confusion about Titration Formula [closed]

When performing a titration of a monoprotic acid and a monoprotic base, water can not be added to the titrant but water can be added to the analyte. To prove this statement to myself, I decided to ...
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2answers
242 views

What is the correct pH value of weak and strong alkalis? [closed]

In the book titled fundamental chemistry for Cambridge O level, it states at page 149, Ammonia solution with a pH of 11.1 is a weak alkali and that's why it shows much lower conductivity of 0.50 ...
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Is there an adhesive that is not dissolved by acetone?

I am trying to glue glass sheets together to make a sealed 13" x 13" x 13" box. Inside this box there would be acetone gas used to melt 3D printed parts to make them more durable. Acetone will remove ...
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Basicity order of 2nd group oxides

It's a general trend that basicity of oxides decreases down the group. But recently I came across a statement "the basicity of second group oxide decreases down the group and decrease in basic nature ...

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