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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1answer
56 views

Titration of multi-basic acid

How would a solution made of $\pu{20 mL}$ of $\ce{NaOH}$, $\pu{10 mL}$ of $\ce{HCl}$, $\pu{10 mL}$ $\ce{NaH2PO4}$ and $\pu{5 mL}$ of $\ce{Na3PO4}$, all of them in a concentration of $\pu{10 mmol/L}$, ...
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1answer
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How is the hydrazone formed in the Wolff-Kishner reduction?

In the Wolff-Kishner reduction the first step is to react a carbonyl with hydrazine to form a hydrazone. The later steps of the reaction requires a strong base to cause loss of nitrogen. However, the ...
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62 views

Why is Ka of weak acid increasing while being diluted?

I am calculating $K_\mathrm{a}$ and percent dissociation of acetic acid being diluted to $\pu{1.00 \times 10^{-1} M}$, $\pu{1.00 \times 10^{-2} M}$, and $\pu{1.00 \times 10^{-4} M}$. The $\mathrm{pH}$ ...
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30 views

Why can indicator pKa be less than the pH at equivalence?

An indicator usually has a pH at equivalence tolerance range around its pKa value that is suitable for titration. However, if the pH at equivalence exceeds the indicator's pKa, wouldn't most of the ...
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19 views

How does the Hygroscopic Properties of Sulfuric Acid Change with the concentration? [closed]

Sulfuric acid is a dehydrating agent, but how does the concentration of the acid affect its ability of dehydrating water? I've read about concentrated sulfuric acid being a dehydrating agent because ...
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0answers
18 views

You mix 55.0 mL of 0.10 M HCl and 110.0 mL of 0.050 M NH3. What is the pH of the resulting solution? [closed]

You mix 55.0 mL of 0.10 M HCl and 110.0 mL of 0.050 M NH3. What is the pH of the resulting solution?
3
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1answer
36 views

Reason for triphenyl methane being less acidic than acetylene

This question came through answering a question that talked about the acidic order of four compounds. Upon researching the actual $\mathrm p K_\mathrm a$ values I noticed that even though there was a ...
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0answers
26 views

Given initial moles of weak acid, find moles of conjugate base to be added to get a final pH (volume unknown)

I am preparing notes on buffers and I came across this problem on a website: Given 10.0 mmol of a weak acid HA with $\textrm{p}K_a =5$, how many mmol of NaA needs to be added to have a final $\textrm{...
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24 views

Why is the conjugate base of HCl (aq) a strong acid, very weak? Why when HCl(aq) dissociates the reaction only goes forward? [closed]

Mainly, I'm wondering why does HCl(aq) want to dissociate so much that when in ionic form, it is hard to recombine. Wouldn't it want to remain HCl to fill the octets? Thanks :)
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1answer
48 views

Notation for inclusion of water in a dissolution equation

Earlier I had a student come by wanting to know how to show the dissolution of $\ce{NH4OH}$ in water. I would think we would just write it: $$\ce{NH4OH(aq) <=> NH3(aq) + H2O(l)}$$ I say this as $...
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46 views

Calculate concentrations of ions after acid-base reaction given volumes and concentrations

A $\pu{35.0 mL}$ of $\pu{4000 ppm}$ $\ce{HCl}$ solution is mixed with $\pu{45.0 mL}$ of $\pu{0.1025M}$ $\ce{NaOH}$ solution. Assume volumes are additive. $$\ce{NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(...
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Problem: What is the pH of a solution for which 20mL of 0.1M HCl solution is titrated with 20mL of a 0.15M CH3NH2 (Methylamine) solution [closed]

What is the pH of a solution for which 20mL of 0.1M HCl solution is titrated with 20mL of a 0.15M CH3NH2 (Methylamine) solution. The K_b (Base dissociation constant) for CH3NH2 is 4.38*10^(-4) Sorry ...
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1answer
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Can you meassure a negative pH value with a pH meter?

I was checking the $\mathrm{pH}$ of $\pu{1 M}$ chromic acid solution, and I got its $\mathrm{pH}$ around -1.7. Yet, $\mathrm{pH}$ of $\pu{0.4 M}$ solution was around -0.6. Could these values be ...
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15 views

Saponification - Oil and Alcohol?

I've been reading that a saponification reaction typically involves NaOH or KOH. I was wondering - could anything that contains an OH group cause a saponification reaction? For instance, coconut oil + ...
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1answer
32 views

Acetic Acid/Acetate Buffer Math [closed]

A chem lab class gave the following problem: You need to make an acetic acid buffer with a pH of 5.15. You have a 0.01 mol solution of acetic acid. What molarity of sodium acetate is required to add ...
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Can you predict ionization states without knowing if the substance is an acid or a base? [closed]

Since the ionization states of a substance at a certain pH value are different if the substance is an acid or a base, I assume that needs to be established first and only then you can continue with ...
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2answers
69 views

Calculating the pH of a 'buffer' solution?

Question: Determine the $\mathrm{pH}$ of the solution resulting when $\pu{100 cm^3}$ of $\pu{0.50 mol dm-3}$ $\ce{CH2ClCOOH}$ is mixed with $\pu{200 cm^3}$ of $\pu{0.10 mol dm-3}$ $\ce{NaOH}$. The ...
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1answer
56 views

Finding a Mistake Calculating the pH of Ammonium Acetate

I'm trying to calculate the $\mathrm{pH}$ of a $\pu{0.10 M}$ solution of ammonium acetate, and I am struggling to find what mistake I am making within the following calculations: We know that $\dfrac{[...
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0answers
34 views

Reactivity of unsaturated organolithium compounds

I'm particularly looking in the context of alkyl lithiums compared to vinyl-lithiums and alkynyl-lithiums. Why is it that shifting from sp3 to sp2, and even further to sp carbanions, reduces the ...
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1answer
74 views

“HBr is donating a proton to LiOH”: Why doesn't it produce LiOH2?

In the section Brønsted-Lowry acid and base theory from Khan Academy: In the reaction $\ce{LiOH(aq) + HBr(aq) -> H2O(l) + LiBr(aq)}$, $\ce{HBr}$ is donating a proton to $\ce{LiOH}$, thus acting as ...
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1answer
62 views

How do acids prevent ferrous sulfate from getting oxidised?

If $\ce{FeSO4.7H2O}$ is dissolved in an acidic environment, for example in 0.05 M aqueous solutions of methanoic or ethanoic acid, would that prevent it from getting oxidized if an oxidizing agent ...
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0answers
20 views

Chemical reactions to make perchloric acid more corrosive to biological substances [closed]

The Martian soil is rich in perchlorates and I was wondering if it could be combined with something to form a more corrosive acid. I am using this to write a book and I want to know if fauna could use ...
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49 views

Possibility of removing two water molecules from glycerol

Not a chemist, but from a chemical formula perspective, how hard would it be to create acetone by acidifying glycerol? $$\ce{C3H8O3 + 2 H+ <=> C3H6O + 2 H2O}$$ Has anyone ever heard of this ...
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64 views

Why is 2-fluorobenzoic acid more acidic than 4-fluorobenzoic acid despite its intramolecular hydrogen bonding?

I was reading about $\mathrm{p}K_\mathrm{a}$ values of 2-fluorobenzoic acid and 4-fluorobenzoic acid and found that the latter had a higher value which was surprising to me. I think that ...
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0answers
31 views

Why is oxalic acid more acidic than benzoic acid?

I came across this fact while reading my book and was confused. Looking at the structures, I had the intuition that benzoic acid would be more acidic as the conjugate base formed will resonate all ...
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2answers
54 views

What happened to the Na+ ion? [closed]

I was in the middle of my acid and base schools questions when I came to a stop at this question. I have posted the answer to tell you what I am confused about. My teacher did not explain this very ...
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0answers
12 views

Calculating nanocluster's Lewis acidity

In general, fluoride ion affinity, ammonia binding energy, photoacoustic IR spectra of adsorbed species (pyridine, CO) are used to measure the Lewis acidity of a material. But in the computer ...
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0answers
21 views

Purify 65% nitric acid to 98% (WFNA)

What is the simplest way to purify 65% nitric acid (HNO3) to white fuming nitric acid (WFNA which is 98% pure)? Is it dehydration with concentrated sulfuric acid (H2SO4)? Is distillation needed to be ...
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2answers
84 views

Why is magnesium ascorbate, which is a conjugate base of a weak acid, acidic? [closed]

Why are magnesium ascorbate and potassium acetate, which are salts of strong bases with weak acids, acidic? I discovered with litmus paper that magnesium ascorbate is acidic and found out from https://...
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0answers
19 views

Reducing salts in tap water

I want to reduce harmful salts in tap water so that it is usable for watering plants. The water in my tap comes from the Colorado river, thus containing a lot of salts, particularly calcium carbonate. ...
3
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1answer
45 views

Why is hydrated beryllium ion acidic?

The beryllium ion, $\ce{Be^{2+}}$, forms the aquo complex $\ce{[Be(H2O)4]^{2+}}$. According to LibreTexts, this complex is acidic in solution: $$\ce{[Be(H2O)4]^{2+} + H2O -> [Be(H2O)3OH]+ + H3O+}$$ ...
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1answer
84 views

Is any element base or acid?

I have seen classification of Mg+2 or any other cation or anion for that matter as an acid or a base, but I have never seen an element labelled as an acid or a base. Isn't there a possibility of Mg+2 ...
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2answers
37 views

Neutralisation of weak acid by base

I'm still working on my concepts related to chemical equilibrium. I came across this question: 10mL of a weak acid HA is 20% dissociated in water. This solution is completely neutralised by 10 mL of $...
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1answer
24 views

“Scrubber” for storing HCl

I'm in need of hydrochloric acid for cleaning parts before electroplating, but I'd rather not deal with the HCl fumes given off by it, as I'd rather keep my workshop contents from rusting. Given that ...
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1answer
38 views

How to calculate how much weak acid would dissociate in water?

So I know water has a pH of 7. If we add 0.1 mol of a strong acid inside 1 liter of water, it WILL fully dissociate into 0.1 mol of A- and 0.1 mol of H+ thus making the pH of the solution 1. But what ...
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2answers
55 views

How to know if a reaction forms H3O+ ions or OH- ions? [closed]

How would you know when an acid or base is paired with $\ce{H2O}$ that it will form an $\ce{OH-}$ ion or a $\ce{H3O+}$ ion? I just started the acid and base equilibrium unit, and I'm just confused on ...
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1answer
156 views

Why is negative charge more stable on sulphur than on oxygen?

Consider this problem: Which is more acidic, $\ce{MeOH}$ or $\ce{MeSH}$? According to my teacher: To determine which is more acidic, figure out which forms the more stable conjugate base. In this ...
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0answers
25 views

Adding aluminum sulfate to neutralize an aqueous solution of sodium silicate with pH of 12.6

How much aluminum sulfate do I need to add to an aqueous solution of sodium silicate to neutralize the solution (pH from 12.6 to 7)? For a water treatment school project, we remove sodium silicate ...
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1answer
39 views

How to Test Auto-Ionization of Ammonia

I was wondering how we could test that the auto-ionization of liquid ammonia actually occurs experimentally. The chemical equation is described below: $\ce{NH_3 <=> NH_4^+ + NH_2^-}$ I was ...
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62 views

Why is salt used in acidic solutions to clean brass?

Most DIY brass cleaning solutions use salt in addition to the acid component whether vinegar or acetic acid. Why?
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1answer
87 views

How to calculate pH of an CH3COOH solution? [closed]

please, does anyone know, how to properly (with calculation procedure) calcutate $\mathrm{pH}$ of an $\ce{CH3COOH}$, when you know only: -$\ce{CH3COOH}$ is 8% (water solution) -density of $\ce{...
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2answers
87 views

Why does this acid-base reaction occur?

My teacher told me about the reaction of sodium peroxide with water: $$\text{Na}_2\text{O}_2 + 2\text{H}_2\text{O} \ce{->} \text{H}_2\text{O}_2 + 2\text{NaOH}$$ Now, the concentration of products ...
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0answers
25 views

What is an acyl group?

An acyl group is defined as being a result of removing a hydroxyl group from an oxoacid. This is supposed to result in a group of the form R-C=O. An oxoacid, in turn, is defined as an acid which ...
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1answer
92 views

Preparation of a HCN/NaCN buffer that has a pH of 9.8 and an osmotic pressure of 1.35 atm at 298 K

You are asked to prepare $\pu{2.0 L}$ of a $\ce{HCN/NaCN}$ buffer that has a $\mathrm{pH}$ of $9.8$ and an osmotic pressure of $\pu{1.35 atm}$ at $\pu{298 K}$. What masses of $\ce{HCN}$ and $\ce{NaCN}$...
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0answers
42 views

Stability of a carbanion that is attached to three phenyl groups

I had come across a question - which asked me to predict the stability of a carbanion attached to 3 phenyl rings, in opposed to one in which the same 3 phenyl rings that are attached to the carbanion ...
3
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1answer
87 views

Why does green ferrous sulfate solution change color to yellow upon addition of hydrochloric acid?

I was demonstrating the formation of $\ce{Fe(OH)2}$ precipitate at school when the light green $\ce{FeSO4}$ I was using reacted with dil. $\ce{HCl}$ turned yellow. This only happened with dil. $\ce{...
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1answer
44 views

How to identify the concentration of nitric acid?

I have quite a small quantity of concentrated nitric acid I had acquired about two years ago. This was given to me by a friend in a couple of Pyrex volumetric flasks with stopper and some in a ...
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1answer
43 views

I have contradictory results in a research paper, how do I proceed with my analysis?

I am performing a simple acid-base titration investigating the efficency of different pure antacid compounds, and in my results, I found out that NaHCO3 neutralized the fastest (using a pH by time ...
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0answers
30 views

Why is hydrated barium peroxide used in the preparation of hydrogen peroxide?

I read about the laboratory method of producing hydrogen peroxide. The chemical reaction in question is: $$\text{BaO}_2.8\text{H}_2\text{O} + \text{H}_2\text{SO}_4 \rightarrow \text{BaSO}_4+\text{H}_2\...
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1answer
35 views

Can a previously neutral mix of chemicals become acidic or alkaline somehow? [closed]

This question relates to Is there any law for pH conservation in chemical reactions? I had basically the same question, but I did not get the answer I was looking for from the above link. For me this ...

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