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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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What makes Coke acidic?

What makes Coke and other soft drinks acidic? These drinks are carbonated, so a freshly-opened can should have a lot of dissolved carbonic acid, but the ingredients also lists phosphoric acid. Would ...
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How does the litmus pH indicator work?

I'm wondering about how does the litmus solution work as a pH indicator. And another question: When you put drops of litmus solution into an colorless acid (e.g. $\ce{HCl}$), it turns red. But then ...
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Synthesis of nitrocellulose

I am trying to understand the synthesis of nitrocellulose. A mixture of sulfuric acid and nitric acid is used to nitrate cellulose. The sulfuric acid acts as a catalyst, producing $\ce{NO2^{+}}$ ions ...
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Why does the hydroxide ion have a negative charge?

I've been studying the roles of hydroxide & hydronium in acids and bases, and it was mentioned that a hydroxide ion (OH-) has a negative charge. Can someone give me a layman's explanation of what ...
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How can I find pKa from a titration curve?

I am fully aware that the pKa is the pH at half the equivalence point, but are there some programs or methods I could use to accurately estimate the pKa without manually drawing lines on the graph?
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Computation of pH when an acid and base are mixed in solution

I'm doing a basic chemistry course, and we are currently learning how to compute $\text{pH}$ from the acid dissociation constant (using $\left[\text{H}^{+}_{(\text{aq})}\right]=\sqrt{K_{a}\left[\text{...
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Acetic acid freezing distilation

How can acetic acid be distilled by freezing when its freezing point is above the freezing point of water. Examples on the web show the water portion of the vinegar as ice and the acid as a liquid ...
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1answer
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Fitting titration curve

To simulate the action of gastric $\ce{HCl}$, we have titrated 100 ml of a meal with 0.1 N $\ce{HCl}$. To plot the data, use (R-code) ...
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1answer
638 views

Is this the correct relative Brønsted acidity in these four acids?

We are asked to sort these four acids by increasing Brønsted acidity: The problem is, I am confused why $\ce{H2F+}$ is the strongest acid of them all. I understand that stronger acids will have ...
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317 views

How can I determine the pH of solution?

Could anyone tell me how I would go about calculating the pH of 100.0 mL of 0.100 M $\ce{H2NNH2}$ ($K_\text{b} = 3.0 \times 10^{-6}$). Furthermore, how would this pH change when 20.0 mL of 0.200 M $\...
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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 ...
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Clogged drain, commercial products are ineffective

I have a clogged drain from my shower. Commercial products like Savo or WC Net totally don't work. Is there any chemical substance which can be bought without permission or which can be made easily to ...
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Which species dissociate completely in ionic equations?

I am tasked with writing a molecular equation, an overall ionic equation, and a net ionic equation for the reaction between an aqueous solution of phosphoric acid, $\ce{H3PO4{(aq)}}$ and an aqueous ...
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1answer
959 views

Understanding the rate of change in titration curves

As I am looking at titration curves, a few things stand out. For now, I have a two part question: When titrating an acid with a base, for instance, the pH rises more or less abruptly around the ...
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Why does polonium form acidic oxides?

All metals form basic oxides. Metallic oxides are basic in character. Polonium is a metal, so it should form basic oxides but it forms acidic oxides. Why are its oxides acidic in character?
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1answer
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How is the yellow colour of nitric acid removed?

Nitric acid obtained in laboratory is slightly yellow due to the dissolution of nitrogen dioxide which is produced due to thermal decomposition of a portion of $\ce{HNO3}$. $$ \ce {4HNO3 -> 2H2O ...
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1answer
467 views

How useful is the assumption that water doesn't auto-ionize in the following?

Now in the first row of the iCe-table, $[\ce{H3O+}]$ is said to be 0. But water autoionizes to some extent, so it shouldn't really be 0. I accept that, because the pH of this solution is 2.5, the ...
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Why would the loss of H₂ to space mean that the Earth's geochemistry would be based on acid/base reactions?

I am reading a paper[1] that contains the line: Most of the $\ce{H2}$ in the Earth's mantle escaped to space early in the Earth's history; consequently, the overwhelming majority of the abiotic ...
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Pipetting strong acid with plastic material

Can I pipette concentrated sulfuric acid using a plastic pipette tip? Will either the plastic or the acid be affected?
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Comparison of acids to dissolve phosphates

I am currently reading this German paper on the dissolution of phosphates by acids and chelants. The authors do a "fast-test" of the dissolving power of different acids which goes as follows: For ...
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Why first water and then acid?

From school, I remember a very important rule: first you need to pour the water and then the acid (when you need to mix them) not vice-versa. This is because otherwise the aсid becomes very hot and ...
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1answer
248 views

How would I neutralize a PEP (Phosphoenolpyruvic) acid?

PEP (Phosphoenolpyruvic acid) is acidic but I need to make it neutral. I need a solution (pH 6-8) of PEP in a final 1 mL volume with a concentration of 100 mM. How would I make this?
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Do hydrogen halides (HX) form strong or weak acids?

I know that when dissolved in water, hydrogen halides ($\ce{H-X}$), become acids. I know that $\ce{HF}$ forms a weak acid, but can it be generalized that all $\ce{HX}$ acids do so?
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Why is nitric acid such a strong oxidizing agent?

In my teaching-lab experiments I've seen that nitric acid solutions are able to facilitate the dissolution of metals such as silver, even though they are more active than hydrogen. Does anyone know ...
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Chemical compounds responsible for the colors in flowers?

I know that anthocyanins are a class of compounds responsible for the purple colors found in flower petals. Anthocyanins (also anthocyans; from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = ...
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How does adding lemon juice to sugar make better caramel?

It's a common cooking advice: if you want a somewhat softer caramel, add some lemon juice to the sugar: To help prevent the caramel from crystallizing, you can add an acid to the sugar before you ...
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Why is arsenous acid denoted H3AsO3?

Inspired by this question, I'm wondering why arsenous acid is frequently denoted $\ce{H3AsO3}$, as opposed to $\ce{As(OH)3}$, which would appear to more accurately reflect its connectivity? [edit] I ...
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How do I calculate the degree of dissociation in equilibrium?

In my textbook, for calculating the percentage dissociation of $\ce{HF}$ for the given equation: $$\ce{HF + H2O <=> H3O+ + F-}$$ The solution is: Initial Concentrations $$[\ce{HF}] = 0.08~\...
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Why are strong acids and bases not suitable as primary standards?

This is one of the questions with which I have puzzled over, and can arrive at no definite conclusion. Why are strong acids or bases, such as $\ce{H2SO4}$,$\ce{ HNO3}$, $\ce{HCl}$, and $\ce{NaOH}$ not ...
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Why are the majority of cleaning solutions basic?

When testing for pH for common household cleaning products, such as dishwasher fluid, I noticed that majority of them tend to be basic? Why is that? Do acid make good cleaning solutions as well?
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Determining the pH of an organic solvent

Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $\mathrm{p}...
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1answer
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Timescale of Protonation and Deprotonation across micelle layers

I am curious about the timescales of protonation and deprotonation of solvent systems. As a followup, how is this affected when the proton source is separated by an organic phase? For instance, it is ...
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What software can calculate aqueous solution equilibria?

What software is available out there to calculate the equilibrium in a set of reactions in aqueous solution? In particular, I'm interested in software general enough to simulate things like titration ...
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1answer
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Side reactions of NHS Chemistry

N-Hydroxysuccinimide (NHS) chemistry is commonly used in chemical biology to react with primary amines like lysine and the N-terminus of proteins. I was curious how labile NHS esters are to other ...