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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15 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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1answer
32 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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0answers
21 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 ...
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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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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
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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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
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 ...
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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 ...
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1answer
25 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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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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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
35 views
What happens if Ka is 1 [closed]
I know that if Ka < 1, the compound is a weak acid and if Ka is >1, the compound is a weak base. What happens if Ka is exactly 1: is a strong or weak base, or neutral?
Also, Kw is < 1, so is ...
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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.
1
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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.
11
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2answers
344 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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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
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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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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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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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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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 ...
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0answers
32 views
Will hydrogen chloride dissolved in ethanol react with magnesium?
Magnesium will react with aqueous HCl to form magnesium chloride and hydrogen gas. Simple. But I've just read in my textbook that HCl in a solution of ethanol no reaction will take place. There is no ...
3
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3answers
255 views
Which acid/base does a strong base/acid react when added to a buffer solution?
I'm in high school chemistry and just learning about buffer solutions. For example, given a buffered solution of $\ce{CH3COOH}$ and $\ce{NaCH3COO}$ with $K_a = 1.8 \times 10^{-5}$, we might want to ...
2
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1answer
117 views
Percent Dissociated from Titration Curve
Question 818 references the titration curve. Answer is A because $\ce{H+}$ conc $= 10^{-4}$. This is conc of dissociated acid. The conc of the undissociated acid is the original concentration minus ...
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1answer
48 views
Why does a weak base, which is also a salt, dissociate completely in water? [closed]
I'm answering a problem where $\ce{KOH}$ and $\ce{KOAc}$ dissociate nearly as much as each other in separate aqueous solutions at equal concentrations. The problem essentially assumed both completely ...
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0answers
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Determination of the most acidic hydrogen in an organic compound
Identify the most acidic hydrogen in the compound below:
Can someone please explain why is $\ce{H^\mathrm{a}}$ in the compound below more acidic than $\ce{H^\mathrm{b}}$?
This is what is ...
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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 ...
1
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1answer
20 views
How can I easily identify if a substance is an acid or base based on its chemical formula? [closed]
I know of the Arrhenius definition, Bronsted Lowry definition and the Lewis definition for acids and bases but I don't know how to apply them on the spot. Also, some chemical formulas (such as acetic ...
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0answers
15 views
Is it possible to determine the pH that results in maximum buffer capacity from a Bjerrum plot?
If buffer capacity is normally at a maximum when pH=pKa because there is an equal concentration of acid and conjugate base in the buffer (so there's an equal amount of substance that can absorb acid ...
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2answers
38 views
Calculating the pH of a buffer made by a diprotic acid and its double salt
The concentration of the diprotic acid (tartaric acid) will be constant at $\pu{ 0.1 M}$. I want to find the concentration of its double salt (potassium sodium tartrate) needed to create a buffer of $\...
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1answer
25 views
Why does buffer capacity of tartrate buffer generally decrease as the buffer pH increases?
From what I see, the buffer capacity of tartrate buffer is generally decreasing as buffer pH increases. Why is this? Also, does this mean that tartrate buffer doesn't have a maximum buffer capacity at ...
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0answers
12 views
What is the formula for theoretical buffer capacity for a diprotic buffer system?
According to Chembuddy, the formula for theoretical buffer capacity for a monoprotic buffer system is as follows:
where Cbuf is the total concentration of buffer and Kw is the water ionization ...
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1answer
39 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 ...
3
votes
1answer
90 views
pH of CH3CH2NH2 buffer solution [closed]
For $\pu{550.0 mL}$ of a buffer solution that is $\pu{0.170 M}$ in $\ce{CH3CH2NH2}$ and $\pu{0.150 M}$ in $\ce{CH3CH2NH3Cl}$, calculate the initial pH and the final pH after adding $\pu{0.020 mol}$ ...
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0answers
33 views
How to confirm a powder is Sodium Hydroxide?
Long-story-short, my mother found a bag of white powder with some soap making supplies. We're about 90% sure it's powdered lye, but I thought it would be fun to confirm this somehow.
Is there a way ...
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0answers
30 views
H+ vs HCl in the gastric juice
Parietal cells in the stomach are known to expel $\ce{H+}$ ions into the gastric juice to keep the pH acidic. When $\ce{H+}$ $\ce{[H3O+]}$ can fully function as acid in the gastric juice, why do cells ...
8
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2answers
170 views
Is oxalic acid dihydrate considered a primary acid standard in analytical chemistry?
Using oxalic acid dihydrate as a primary standard just seems really odd to me. I'd expect a primary standard to be oven dried. It just seems weird that a hydrate would be used.
Granted, I saw ...
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0answers
19 views
Steps of crystallization
An excess of copper(II) oxide is added to dilute sulfuric acid to make crystals of hydrated copper(II) sulfate.
The processes listed may be used to obtain crystals of hydrated copper(II) sulfate.
...
2
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2answers
47 views
Why isn't my galvanic cell making enough voltage?
I'm in kind of a pickle here. I made a galvanic cell of Lead and aluminium for a chemistry internal assessment but unfortunately, it didn't turn out so well and neither me nor my teacher has any clue ...
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1answer
44 views
How to standardise NaOH? [closed]
My aim is to "To determine the concentration of citric acid in lemon juice using titration technique." and as following i need to standardise the NaOH in order to titrate it with validity. Is there a ...
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 ...
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1answer
38 views
Effects of Ka on the Half-Equivalence Point
I'm new to studying chemistry at a university level and am currently reviewing acid-base titrations. I am wondering about the relationship between your ionization constant for a weak acid ($K_\mathrm{...
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0answers
21 views
pka table of acid and conjugate base question [duplicate]
hydroxide ion has pKa value of 15.74, and there's no problem with it, Table shows acid side of conjugate bases. is it right?
pka and pkb of water is 15.74. they are same. why?
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0answers
13 views
How to describe the ionization equilibria of multiple ionizable species
For a weak acid [PB] in a buffered solution [H2PO4]/[HPO4] at pH 7.5 where:
If some of the species [PB] was removed from the solution by partitioning on to an adsorbent, the equilibrium of [PB] ...
