62
votes
Accepted
Why does potassium react more violently with water than lithium?
For the reaction,
$$\ce{M -> M+ + e-}$$
the heat liberated is highest for lithium owing to its high negative $E^\circ$ value so one would think that the reaction must be most vigorous.
The ...
- 5,256
41
votes
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How does ammonium nitrate explode on its own?
It is known that ammonium nitrate decompose exothermically when heated to form nitrous oxide and water. This paper1 notes that the irreversible decomposition of ammonium nitrate occurs at the ...
- 22.3k
36
votes
Accepted
How can I predict if a reaction will occur between any two (or more) substances?
Can I predict the products of any chemical reaction?
In theory, yes!
Every substance has characteristic reactivity behavior. Likewise pairs and sets of substances have characteristic behavior. For ...
- 41.5k
30
votes
Why does zinc react with sodium hydroxide?
Indeed, $\ce{Zn}$ is lower than $\ce{Na}$ in activity series of metals, so the following reaction won't take place
$$\require{cancel}\ce{Zn + 2NaOH \cancel{→} Zn(OH)2 + 2Na}$$
Remember, however, ...
- 18.5k
29
votes
How does ammonium nitrate explode on its own?
Ammonium nitrate ($\ce{NH4NO3}$) is widely used in the fertilizer industry and is one of the most concentrated forms of nitrogen fertilizer (35% of $\ce{N}$). At the same time, it has also been widely ...
- 35.1k
28
votes
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Friedel–Crafts reaction of phenol
Like aniline, phenol too reacts to a very less extent during Friedel-Crafts reaction.
The reason being that the oxygen atom of phenol has lone pair of electrons which coordinate with Lewis acid.
...
- 692
23
votes
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Why is gold unreactive when only one electron is in the outer shell?
First off, gold does react. You can form stable gold alloys and gold compounds. It's just hard, mostly for reasons explained by the other answer
The reason bulk gold solid is largely unreactive is ...
- 26.9k
19
votes
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If aliens lived in a hydrogen (or any flammable gas) based atmosphere, would they perceive oxygen to be flammable?
Absolutely yes.
Lighting a torch in such an environment would simply be the reverse physical process (and same chemical process) of what is done in our oxygen-containing atmosphere. In the chamber ...
- 16.7k
18
votes
Why is a ketone more nucleophilic than an ester?
The ester carbonyl carbon is a stronger nucleophile and less prone to nucleophilic attack than the carbonyl carbon in a ketone. I think you are trying to understand why the carbonyl in a ketone ...
- 82k
18
votes
Rationalising the order of reactivity of carbonyl compounds towards nucleophiles
Here is my "old school" explanation.
Below is a drawing of the reaction coordinate for nucleophilic attack at a carbonyl carbon. The energy well for the starting carbonyl compound is shown on the ...
- 82k
17
votes
Why is gold unreactive when only one electron is in the outer shell?
Relativistic effects account for gold's lack of reactivity. Gold has a heavy enough nucleus that its electrons must travel at speeds nearing the speed of light to prevent them from falling into the ...
- 82k
17
votes
Why does superglue ignite cotton?
Though the monomers in cyanoacrylate glues contain an ester, their polymerization doesn't rely on that ester group directly. The Wikipedia article for cyanoacrylates shows the polymerization more ...
- 4,291
16
votes
Why is a ketone more nucleophilic than an ester?
Looking at the partial charges of esters and ketones, unfortunately ron's answer is only half true. For a simple model I have chosen 3-pentanone and ethyl acetate. You can see, that the carbonyl ...
- 42.3k
16
votes
Rationalising the order of reactivity of carbonyl compounds towards nucleophiles
For this approach I am basically employing Frontier Molecular Orbital Theory (FMO) to predict the reactivity of carbonyl compounds towards nucleophiles.
For the purpose of this explanation I have ...
- 42.3k
16
votes
Why doesn't copper react with hydrochloric acid while the other metals do?
You might want to look up some terms, such as
noble and less noble metals
reduction potential
galvanic series
Here, reaction means that
hydrogen gas is formed
the metal is dissolved
In order to ...
- 43.1k
16
votes
Accepted
Why is the iodide anion a good nucleophile but a poor base?
You should clarify whether the iodide anion is a good nucleophile in a polar protic or polar aprotic solvent.
Also let's note that nucleophilicity is a kinetic property, while acidity/basicity are ...
- 17.8k
14
votes
Accepted
Why is zinc more reactive than copper?
You have to think about the whole process. When a metal loses electrons to make a metal ion the following happens:
The metallic bonds holding the metal atoms together are broken.
The metal atom ...
- 3,770
14
votes
Accepted
Comparing SN2 reaction rates
There are a number of factors that can influence the rate of an $\mathrm{S_{N}2}$ reaction. Solvent, leaving group stability, attacking group nucleophilicity, steric factors and electronic factors.
...
- 82k
14
votes
Friedel–Crafts reaction of phenol
To add to @user223679's answer. Phenol can react via two pathways with acyl chlorides to give either esters, via O-acylation, or hydroxyarylketones, via C-acylation.
However, phenol esters also ...
- 14.9k
14
votes
Accepted
Singlet/triplet oxygen cycloadditions
Normal dioxygen ($\ce{O2}$) exists as a ground state, triplet biradical. This is an example of a molecule that, thermodynamically should be quite reactive, yet is kinetically unreactive - once again, ...
- 82k
14
votes
Accepted
Why are beta-ketoacids better at decarboxylation than gamma or delta?
It has to do with the stability of the electrons that are ejected from the bond that breaks. In B-ketoacids, the electrons can resonate onto the oxygen and form an enol/enolate intermediate, which is ...
- 399
14
votes
Accepted
Comparing SN2 reaction rate for phenacyl chloride and methyl chloride
First, let me point out that a rate difference of 500 is really not that large. There are solvolysis reactions with relative rate differences on the order of $\mathrm{10^{10}}$ or greater (1).
The ...
- 82k
14
votes
How does ammonium nitrate explode on its own?
First,
ammonium nitrate is a kind of mixture between an oxidizer - the nitrate part - and a reducer - the ammonium one. This is at the core of your question.
The direct decomposition correctly ...
- 3,514
13
votes
Accepted
Why does N₂ react with O₂ to Form NO at high temperatures?
$\Delta G = \Delta H - T \Delta S$
In the case of the $\ce{N2 + O2 -> 2NO}$ , $\Delta H$ and $\Delta S$ are both positive, so the reaction is thermodynamically favorable at high temperature (such ...
- 38.9k
12
votes
Is there a way to contain fluorine gas for long term so that it can be visually observed?
As @JonCuster mentions, some materials are pretty resistant to fluorine gas at room temperature.
But out of curiosity, I checked Theodore Gray's website. He's made an effort to have a "periodic table"...
- 26.9k
12
votes
Accepted
How does steric hindrance cause sulfur hexafluoride to have almost no reaction chemistry?
As you can see:
Sulfur (16) is significantly smaller than Se (34). That size difference
means that there is more room between the fluorine atoms on Se than on
Sulfur. That is what steric hindrance ...
- 2,596
12
votes
Accepted
Does an acetal give a positive Tollens test?
The description of the hydrolysis of an acetal is accurate. The trouble is that the initial protonation event happens to such a small amount that the reaction does not proceed. We can estimate where ...
- 10.4k
12
votes
Rate of EAS in chlorobenzene and fluorobenzene
We need some data to answer your question. As presented in this earlier answer (which is also relevant to this question), here are the relative rates for electrophilic aromatic nitration of the ...
- 82k
11
votes
Accepted
What makes R-MgX a more reactive Grignard reagent than R-Cu?
The difference in electronegativity between copper (1.9) and magnesium (1.3) is the key difference.
Since copper is more electronegative than magnesium its electronegativity is much closer to that ...
- 82k
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