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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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43 views

How do I calculate the hydronium ion concentration if I know the strontium hydroxide concentration?

This is my first question so I would appreciate feedback on how to ask better questions. Forgive me if I don't know how to properly format math/chem. The guide is confusing. I was taking a practice ...
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2answers
38 views

How can we tell if an ion is amphiprotic

If I had the following ions: $$\ce{HCO3^-}$$ $$\ce{H2PO4^-}$$ $$\ce{CH3COO^-}$$ Which ones would be amphiprotic? Looking at my $ K_A$ chart, it looks like each ion is formed by the disassociation of ...
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2answers
219 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
454 views

Enthalpy of neutralisation for weak acids and weak bases at standard state

I recently read about why for weak acids and bases the enthalpy of neutralisation is less as compared to the strong ones. This was because the acids and bases being weak, they dissociate incompletely ...
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4answers
5k views

What's the strongest known organic acid?

What's the strongest known organic acid? Is it maybe trifluoromethanesulfonic acid or tautomer of pentacyanocyclopentadiene? EDIT: Since the question was reactivated I thought about formalising it. I ...
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0answers
22 views

Adding apple cider vinegar to a solid DIY deodorant

If I wanted to add a bit of apple cider vinegar to my oil based deodorant, to increase antimicrobial properties, would this cause me to need a preservative? My deodorant is not water based, so I don't ...
3
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2answers
492 views

Predicting pH of an acidic salt of an weak acid and weak base

Suppose we want to calculate pH of an $\ce{NH4HCO3}$ solution of known concentration. Now, $\ce{NH4+}$ will be hydrolised to give $\ce{H+}$ ions. Some $\ce{HCO3-}$ ions will be converted to (i) $\ce{...
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1answer
815 views

Zwitterion (amino acid) equilibrium and the equilibrium constant

I just had my biology test paper back from my teacher, and my teacher insisted that when functioning as a buffer in an alkaline solution, the amino acid deprotonates by the ammonium group instead of ...
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1answer
42 views

Does hyperconjugation into sigma-star explain methylamine's increased basicity relative to ammonia?

The inductive effect with the polarisation of the C-N bond obviously plays a role in stabilising the positive charge of the conjugate acid. But given the similar electronegativities for C and H, CH3 ...
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1answer
23 views

Diluting a sample of weak base before titration. What happens to equivalence point pH of diluted vs undiluted?

A student titrated a 10.00 mL of 0.20 M methylamine ($\ce{CH3NH2}$) and determined that 10.00 mL of $\ce{HCl}$ was needed to reach the equivalence point. If you diluted your original sample of ...
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0answers
14 views

Basicity of subsituted amines

In comparing hydroxylamine, hydrazine, and methylamine for basicity, the order of increasing basicity is hydroxylamine < hydrazine < methylamine. I tried to reason this trend based on electron ...
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0answers
952 views

Application of limiting reagents and acid-base stoichiometry

I'm having a bit of trouble with the latter questions of this problem. $\pu{15.0 mL}$ of $\pu{1.4 M}$ $\ce{HCl}$ was mixed with $\pu{1.00 g}$ of $\ce{CaCO3}$ until all the solid had dissolved. The ...
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1answer
27 views

Acidic strength of phenol [on hold]

Acidic strength comparison of o-floro phenol, o-chloro phenol, o- bromo phenol, o-iodo phenol
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2answers
24 views

Negative charges in acid-catalyzed reactions [on hold]

Whenever my professor draws a mechanism in an acid-catalyzed reaction, he always says you can't form negative charges. Why is that?
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0answers
14 views

Vinegar dilution [on hold]

I would like to ask what would the pH level when 150 mL of 5% distilled white vinegar (pH ~2.4) was diluted with water to get 375 mL of 2% acetic acid? Thanks!
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0answers
15 views

Titration Equivalence Point [on hold]

For the experiment 0.020 Concentration of 35 ml of H2SO4 and 20 ml of Ba(OH)2 was used What is the mole of H2SO4 at equivalence point? Moles of Ba(OH)2 at equivalence point? Molar concentration of Ba(...
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2answers
23 views

Sodium Sulfate vs Sodium Sulfite

I recently took a test and one of the questions was: Which procedures will allow a student to differentiate between solid sodium sulfate and solid sodium sulfite? I. Make solutions of each ...
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1answer
28 views

By how many pH units does rain vs distilled water change a soil pH test?

Sources state that the concentration of $\ce{H2CO3}$ in rain is of a few µmol; I don't know if that's per ml. The buffering effect of most soils is >1000 µmol $\ce{H+}$/kg. Is the difference from low ...
32
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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
18 views

Acidity order of carboxylic compounds

Arrange the following acids in decreasing order of acidity: (a) X > Z > Y (b) X > Y > Z (c) Z > X > Y (d) Z > Y > X I arrived at option (c) according to -I effect, but the answer ...
1
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1answer
26 views

Arrange the following in increasing order of acidity: water, ammonia, ethyne and ethane

I know that ethyne is more acidic than ethane because of more s character. For water and ammonia, I used the fact that oxygen is more electronegative than nitrogen and will be able to stabilize the ...
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6answers
8k views

Decreasing order of basic strength

I need to find the decreasing basicity of the following compounds(I, II, III, IV, respectively): I know that to compare the basic strengths, we need to find the stability of their conjugate acids. ...
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0answers
13 views

Naming convention for buffer solutions/systems

Is there an official naming convention to follow for buffer solutions/systems? I've noticed that the name of the buffer usually just follows the name of the salt (ex. sodium acetate buffer), but what ...
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0answers
13 views

What are a lone pair of electrons? [closed]

What are a lone pair of electrons do they participate in chemical reactions are they valence electrons.
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1answer
71 views

Pale blue species forming during electrolysis of NaHCO3

I have a solution of 3500 ml $\ce{H2O}$ + 454 g $\ce{NaHCO3}$ in electrolysis at a potential of 12.5V using a lead anode and copper cathode. The surface areas aren't measured but they are enormous. I ...
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1answer
2k views

Comparing Acidic Strength of H3PO4 and H3AsO4

The $pKa$ values for H3AsO4 and H3PO4 are $2.30$ and $2.12$ which indicate that H3PO4 is a stronger acid compared to H3AsO4. I looked up their electronegativity values to find that they are almost the ...
19
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4answers
56k views

Why is salt needed when using vinegar to clean pennies?

Let's say you have a solution that is vinegar and it has salt (NaCl) dissolved in it. Then you place old dull pennies in it. Then you look at it 5 minutes later and the pennies are clean and looking ...
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0answers
14 views

Predicting Glycine-HCl's multiple equivalence points

I have currently completed a titration curve for glycine-HCl (2omL @ 0.1M, therefore 2.0mmol) where I have the known pH at each interval of added NaOH (adding 4mL each interval of 1.0M then measure pH)...
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0answers
17 views

Why exactly is sulphuric acid a good dehydrating agent?

I have seen in many organic reactions (such as esterificatiton) that sulphuric acid is added both as a catalyst and a dehydrating agent. What I don't get is exactly how this strong acid is able to ...
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0answers
13 views

How can I dissolve photography film?

I am looking to completely dissolve negative film strips. Acetone was my first try and did not work. If anyone knows/ or has any ideas i would be so greatful.
9
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1answer
2k views

Identifying a glass frosting chemical

I have purchased an "unknown" white coloured powder from the market which can frost glass objects. Here are some properties of this powder White in colour When mixed with HCL or water, it results in ...
2
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2answers
1k views

What's happening at the beginning of a weak acid titration?

At the beginning of a Weak Acid/Strong Base titration curve there is a sharp decrease in $[\ce{H+}]$ and a sharp increase in pH before the ratio between the weak acid and it's conjugate base becomes ...
2
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0answers
229 views

Comparing pKa of Alpha and Beta Amino Acids

The $\mathrm{p}K_{\mathrm{a}}$ of the functional groups in L-glutamic acid (shown below on the right) from left to right are $4.1$, $9.5$, and $2.1$. Predict the $\mathrm{p}K_{\mathrm{a}}$ values of B-...
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1answer
53 views

Kb values of N,N-dimethylaniline derivatives [closed]

I need the $K_\mathrm{b}$ values for ortho-, meta- and para- positions of the following compounds: I've looked and couldn't find them anywhere.
2
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2answers
709 views

Stability of carbanion

I am confused about how one can determine the stability of carbanions using pKa-values. I know that the stability of carbanions can be determined by the inductive effect, hybridization of the charged-...
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2answers
346 views

How does strength of boric acid solution increase in presence of salicylic acid?

A while ago, I read that salicylic acid can make boric acid solution strongly acidic when it's added to it. To my knowledge, I know that boric acid becomes a strong acid in presence of cis-diols (...
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1answer
275 views

In the graph provided, which of the substances is the most efficient in acting as an antacid?

If every dot represents the addition of 0.1 g of the respective base. I suppose that the best would be the one that reaches the highest pH, in the shortest time, for example Calcium Carbonate, but if ...
12
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1answer
842 views

Nucleophilicity/basicity in protic and aprotic solvents

In polar aprotic solvent, why is $\ce{F-}$ a stronger nucleophile than $\ce{I-}$? What I think: If I talk about their basicity, $\ce{F-}$ would be more basic due to instability from its high electron ...
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1answer
43 views

How to use Lewis theory to differentiate between an acid and a base?

According to Lewis theory a material is an acid if it accepts an electron pair, and a material is base if it donates an electron pair. But if we compare the structures of $\ce{HNO3}$ and $\ce{NaOH}$, ...
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2answers
30 views

Unit analysis for neutralization reaction

What volume of $\pu{0.500 mol L-1}$ $\ce{HCl}$ (in $\pu{mL}$) is required to neutralize $\pu{2.02 g}$ of solid $\ce{NaOH}$ pellets? So far I have tried regular unit analysis: 2.02 g NaOH * 1mol ...
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1answer
42 views

Calculate pH at equivalence point [closed]

Calculate the pH at the equivalence point of a titration of 62 mL of 0.1 M $\ce{CH_3NH_2}$ with 0.20 M HCl. The $\ce{K_b}=4.4\cdot10^{-4}$. At the equivalence point, the moles of CH3NH2 equals the ...
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2answers
26k views

Neutralization reaction between ammonia and nitric acid

Complete and balance the following molecular equation (in aqueous solution); include phase labels. Then, write the net ionic equation. $~\ce{NH_3 + HNO_3 -> ?}$ I thought that the acid $\ce{...
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1answer
38 views

Can buffer solutions be used to control the pH of ethanol?

For my experiment, I want to investigate the effect of differing pH on the solubilities of a sparingly soluble drug. However, the solubility is too low for me to conduct a reliable study on the ...
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1answer
30 views

Order of acidity and basicity

Could someone please explain to me the exact reasons for these abnormal orders of acidity and basicity which i am failing to explain by normal reasons like inductive and mesomeric effect? The pka ...
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1answer
57 views

Lewis acid character

Which will have more lewis acid character out of $\ce{BCl3}$ and $\ce{AlCl3}$ ? My attempt: In $\ce{BCl3}$, the back bonding takes place and there is 3pπ-2pπ overlap and in $\ce{AlCl3}$ it is 3pπ-...
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2answers
228 views

Is there a terminology contradiction about whether the conjugate of a strong acid is a “weak base”?

(Please note, I am not simply asking, "Is the conjugate of a strong acid a weak base?" I'm asking about the contradictory ways those terms seem to be used.) I was revisiting strong/weak acids/bases ...
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0answers
18 views

Preparation of sodium acetate buffer

May i know if pH1.2 (0.1NHCl) is the same as sodium acetate buffer pH1.2? and if pH6.8 phosphate buffer same as sodium acetate buffer pH6.8. If they are not the same, what are the difference? thank ...
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1answer
174 views

Obtaining activity coefficients of conjugate acids of some common carboxylic acid molecules

Recently, I have been wondering about justifying the notion on how some common acids (e.g. carboxylic acids) are themselves weaker bases than water to the point that we don't usually consider them to ...
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4answers
139 views

Tricky exam question [closed]

The mark scheme says carbon dioxide is produced from carbonate + acid. I know hydrogen can't be produced because both the reactions are endothermic. But where did the acid come from? Can someone give ...
2
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2answers
62 views

Low-cost nontoxic corrosion inhibitor for steel exposed to hydrochloric acid

It seems that many commercial descaling solutions designed to remove scale (calcium carbonates, etc that form on water heaters) are a simple combination of an acid and an acid corrosion inhibitor for ...