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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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172 views

Why does hydrolysis of OF2 give a neutral solution?

I found this equation on the internet for the hydrolysis of $\ce{OF2}$: $\ce{OF2 + H2O -> HF + O2}$. So, according to me, $\ce{HF}$ must make generate an acidic instead of neutral solution. But ...
2
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1answer
539 views

How can Arrhenius bases also be Brønsted-Lowry bases?

According to ChemGuide, The Brønsted-Lowry theory doesn't go against the Arrhenius theory in any way - it just adds to it. According to Study.com: All Arrhenius acids and bases are also ...
2
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0answers
68 views

Lewis Acid/Base Chemistry [duplicate]

I'm looking for some clarification on Lewis Acid/Base Chemistry. For the Acids do they have to accept a full pair of electrons to be considered a Lewis acid, or do they just have to accept an ...
6
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2answers
195 views

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 ...
1
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1answer
283 views

How to calculate the equilibrium constant of acetic acid-hydroxide ion equilibrium?

I am trying to calculate the equilibrium constant of the following equilibrium: $$\ce{CH3COOH (aq) + OH- (aq) <=> CH3COO- (aq) + H2O (l)}$$ I am aware that this reaction essentially goes to ...
3
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1answer
92 views

are half of “H2SO4 pH sample problem” webpages just wrong, or am I wrong?

I did a Google search for "h2so4 pH sample problem" and went through the results, and it looks like about 50% of the webpages "explaining" how to do this problem give the wrong answer when calculating ...
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1answer
225 views

Evaporation of concentrated formic acid and semi-concentrated sulfuric acid at room temperature

I recently looked at a reaction where CO is synthesized using formic acid and sulfuric acid, which seems to be one of the easier to control reactions for this, and obviously ventilation etc is ...
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1answer
50 views

Why do we use different arguments for determining the strength of hydracids and solubility of ionic compounds?

HI is a stronger acid than HF. Why? Because when dissolved in water, the bigger iodide ion handles the negative charge way better than the small fluoride ion. So Iodide ion is a weak conjugate base ...
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1answer
318 views

Calculating PH of solution after adding strong acid (equilibrium)

Consider the classic example when talking about acids and bases: Say you have 1M of $\ce{HCL}$ and you throw it into water, calculate the resulting pH (= concentration of $\ce{H3O+}$). The way this ...
31
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9answers
8k views

Would it be possible to destroy gold?

I'm a writer. I have a scenario in which a sizable amount of gold needs to be rendered unusable, preferably completely destroyed. I know an acid like aqua regia is able to dissolve gold, but would ...
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0answers
71 views

Two differing methods for vanadium extraction

The following sources (Source 1, Source 2) both cover the extraction of Vanadium (specifically Vanadium Pentoxide, $\ce{V2O5}$) from petroleum residue (petcoke and flyash respecitvely). However when ...
2
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2answers
251 views

How to determine the order of acidity of the following dimethyl nitrophenols

This is how I went about it, although I got a wrong answer: 3,5-Dimethyl-4-nitrophenol (2) shows the nitro group to be sterically hindered, due to which it should go out of plane and this will be an ...
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1answer
87 views

Determining volume of acid needed to be added to reach a specific pH

Suppose there are $\pu{0.024}$ moles of $\ce{Na2HPO4}$ in a $\pu{0.250L}$ solution. How would we calculate the amount of $\pu{0.145M}$ $\ce{HCl}$ needed to reach a $\mathrm{pH}$ of 6.60? I have ...
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2answers
66 views

Why does pH increase as a weak acid becomes more dissociated?

From Wade's Organic Chemistry [1, p. 71]: In most cases, the $\mathrm{p}K_\mathrm{a}$ of an acid corresponds to the $\mathrm{pH}$ where the acid is about half dissociated. At a lower (more acidic) ...
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1answer
123 views

What mass of potassium lactate is needed to 300.0 mL of 0.238 M Lactic acid solution to make a solution with a pH of 4.00? pKa (lactic acid) =3.86

Upon attempt, I've yielded an answer of 11.91g. My calculations do not take 300 mL Lactic acid solution into account, and now I somewhat know the error is at least partially due to the fact that my ...
8
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2answers
216 views

Why is acetone less acidic than cyclohexanol?

The $\mathrm{p}K_\mathrm{a}$ of acetone is 19, whereas the $\mathrm{p}K_\mathrm{a}$ of cyclohexanol is 16. However, acetone is resonance stabilized and its major resonance structure displays the ...
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1answer
788 views

Is Sodium Hydroxide a Bronsted-Lowry Base?

I know that sodium hydroxide dissociates into sodium cation and hydroxide, so it must be an Arrhenius base. I am also aware of the rule that all Arrhenius acids and bases are considered to be Brønsted-...
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2answers
131 views

Predicting products of chemical equations? [duplicate]

Consider the equation $\ce{2 NaOH (aq) +Cl2 (g) —> NaOCl (aq) + NaCl (aq) + H2O (l)}$. How would one know the products of this reaction? Is there a general way of doing this? I would have no ...
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1answer
51 views

Why can't negative charge on a carbon have resonance with a neighboring alcohol?

In these resonance forms of a conjugate base of ascorbic acid, why can't the electrons on the negatively charged carbon in the third form be used to form a double bond with the alcohol and thus ...
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0answers
24 views

How would you make a pH 6 tetraborate buffer using NaOH?

I'm helping a Grade 11 student doing an EE on determining lead soil content. We found a good, doable procedure for it, but one of the reagents is a borate buffer that doesn't seem to have a recipe ...
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2answers
279 views

Comparing basic strength of nitrogen heterocycles

Compare the basic strength of the following compounds: d > b > c > a c > b > a > d c > a > b > d a > d > c > b I know that in compound (c), the π-bond between nitrogen and ...
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0answers
36 views

Buffer/ Indicators / % protonated

I have a buffer with a pH of 5. First I need to find what indicator to use. My options are (Thymol Blue - $\mathrm{p}K_\mathrm{a} = 8.9$), (Bromothymol Blue- $\mathrm{p}K_\mathrm{a} = 7.1$), or (...
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1answer
198 views

Preparing 1M acetic acid buffered with 1 M Ca-acetate to specific pH

I am prepping a buffer solution of 1M acetic acid and 1M calcium acetate with a pH of 5, but it has been a long time since chem 101. I have some notes from an old lab mate that suggested that 600mL of ...
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1answer
35 views

Titrations in three equibilums

You have three solutions: 0.1 M solution of a weak monovalent acid 0.1 M solution of a strong monovalent acid 0.1 M solution of a weak divalent acid Each solution is titrated with 0.15 M NaOH. What ...
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2answers
747 views

Is sodium acetate a neutral or a basic salt?

I read somewhere that salts which do not contain a replaceable hydrogen or hydroxyl group are classified as normal salts. But I also know that strong base-weak acid salts are basic in nature.
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3answers
86 views

If i keep adding sulfuric acid into water, will it keep dissolving forever?

If i keep adding sulfuric acid into water, will it keep dissolving forever?
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1answer
116 views

Examples for oxidation of fluoride and for fluoride as a base

I have no university degree in chemistry and I’m curious about some examples - explained with the applicable rules (or the exception from the existing rules) - for the following statements (from this ...
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0answers
463 views

How does dilution affect the pH of a solution of a weak acid(or base)?

There is a rule that says "Diluting a weak acid increases its pH (towards 7)" and another rule saying that according to Henderson's relation upon diluting a solution of a weak acid and its conjugate ...
8
votes
1answer
93 views

Why does nitric acid have a different molecular structure from phosphoric and arsenic acids?

I remember that this really bugged me as an undergrad, and upon revisiting some inorganic chemistry notes I realized I still don't have a satisfactory answer for it. The structure of nitric acid, $\ce{...
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1answer
78 views

Different HCl concentrations and iron nails [closed]

Hey guys I am at high school and we have a project on designing our own lab. My questions is will different concentrations such as 10%, 20%, 30% and 37% have an affect on the corrosion of an iron ...
4
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2answers
273 views

Basicity comparison of ammonia derivatives (and guanidine)

Arrange the following in decreasing order of basicity: $\ce{N(CH3)3}$ Guanidine $\ce{N(C6H5)3}$ $\ce{NH(CH3)2}$ My answer - 2 > 1 > 4 > 3 Option '2' due to equivalent resonance ...
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0answers
96 views

What is first protonated aldehyde or lactone?

In a six membered lactone with carbaldehyde in beta position, which oxygen gets protonated first? the lactone or the aldehyde? (Using concentrated HCl)
4
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0answers
34 views

No phenolphthalein mono-anion?

This is a follow-up to the question here. There is no mono-anionic stage shown, does it "disproportionate" to the neutral molecule and the di-anion?
4
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1answer
150 views

How many protons does phenolphthalein lose in basic solutions?

So, I've looked it up and Wikipedia claims that two protons are released by Phenolphthalein when pH is over 8.2, but I've seen other sources that claim only one proton is lost. So, is it really just ...
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2answers
97 views

Why is it that all strong bases contain at least one hydroxide bond?

Why is it that all strong bases contain at least one hydroxide bond? What is going on here at the chemical level? For example, we know that $\ce{NaOH}$ is a strong base. I know it is strong because it ...
2
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2answers
334 views

Are the best buffers those that are in a 1:1 ratio with its conjugate acid/base?

I wanted to comment this, but I don't have enough reputation, so I just made this a question. I know that buffers and their conjugate base/acid must exist in similar amounts for the buffer to be ...
2
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1answer
68 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.
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1answer
483 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
47 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
34 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
57 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
220 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
527 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+ ...
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1answer
81 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
401 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
120 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
152 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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2answers
117 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 ...