Most Popular
1500 questions
15
votes
1 answer
Negative ions and health: pseudo science or something more?
Over the last year or so I've heard from friends, who subscribe to holistic medicine, talk about negative ions, saying that they are good for your mental/physical health. Being the only one among them with a chemistry background, I was suspicious…
John Snow
- 4,515
- 6
- 29
- 66
15
votes
4 answers
General rules for deciding volatility
Given an organic compound, is there any way to decide if it is volatile (or compare volatility--everything is volatile in the end)?
Volatility is due to the tendency to evaporate. The conclusion I can draw from this is that a more volatile compound…
ManishEarth
- 15,177
- 14
- 76
- 114
15
votes
1 answer
Why is osmium the densest known element?
Why is osmium so dense despite there being heavier elements after it in the periodic table?
user10153
15
votes
2 answers
The effect of hyperconjugation on the stability of alkenes with MO theory
Hyperconjugation stabilizes carbocations and that makes sense because electrons are given to the empty p orbital.
But how does it stabilize alkenes? Can molecular orbital theory be used to explain it?
biogirl
- 1,370
- 8
- 20
- 35
15
votes
1 answer
Why does hydrogen bonding in salicylic acid make it more acidic?
When salicylic acid deprotonates (losing the proton from the carboxyl group) it forms a hydrogen bond with between the oxygen in the carboxylate anion and the hydrogen in the alcohol group. However, surely there will be a steric clash between these…
RobChem
- 9,784
- 34
- 84
- 143
15
votes
1 answer
Why do the d orbitals have these notations?
Why do the d orbitals have the following notations: $xy, yz, xz, z^2$ and $ x^2-y^2$? What do they represent in their wave-functions?
EJC
- 14,302
- 15
- 67
- 157
15
votes
3 answers
Why the salts in a salt bridge?
Take the example of a copper and zinc galvanic cell, connected by a salt bridge of $\ce{KNO3}$. I understand how the reactions will result in positive and negative charges, and that the ions of the salt will migrate to maintain neutrality. But why…
QCD_IS_GOOD
- 1,118
- 6
- 15
- 27
15
votes
3 answers
CO2 removal from mushroom growing tent
I'm trying to grow oyster mushrooms that like high temperatures. They look great in an indoor terrarium, and can eventually yield several tasty meals :)
However oyster mushrooms are hard to grow indoors, because they need low $\ce{CO2}$ levels…
netom
- 273
- 2
- 7
15
votes
3 answers
Why is active mass of a pure solid or liquid always taken as unity?
Active mass is defined as the molar concentration ie. number of Gram-moles per litre.
My book then wrote
Active mass of pure solid/liquid is always 1 .
The book reasoned that
Molar concentration is directly proportional to density. Since…
user5764
15
votes
3 answers
If caffeine is an alkaloid, why is coffee acidic?
I have just put together on my mind these two facts: caffeine is an alkaloid and brewed coffee is slightly acidic (pH = 5).
My Biology teacher and my Chemistry teacher could not elaborate satisfying answers, but my Physics teacher said it could be…
Dela Corte
- 161
- 1
- 1
- 5
15
votes
3 answers
If a crystal has alternating layers of different atoms, will it display different properties depending on which layer is exposed?
Many metal diboride compounds like $\ce{MgB2}$, $\ce{TiB2}$, and $\ce{ReB2}$ have laminated crystal structures with alternating sheets of metal atoms and boron atoms. If we polish the surface to ensure that only one type of atoms are facing…
哲煜黄
- 571
- 2
- 8
15
votes
3 answers
Why are weak acids weak?
What are weak acids? My chemistry and biology classes skimmed over them briefly but nothing in depth. I understand that an acid is weak if it partially dissociates and breaks down into ionic compounds, but they never stated why.
So my question is…
Pi_Co
- 559
- 2
- 5
- 10
15
votes
1 answer
What happens if you carbonate ethanol?
The electronics youtuber bigclivedotcom has an on-and-off-again series where he carbonates various types of alcohol and comments on the taste. One thing he's noticed is that the stronger the alcohol, the more carbon dioxide it will absorb; so, he…
David Given
- 261
- 2
- 5
15
votes
4 answers
Which is more basic, hydrazine or ammonia?
Which of the following will be more basic, hydrazine $\ce{H2N-NH2}$ or ammonia $\ce{NH3}$?
My chemistry teacher said that $\ce{NH3}$ is more basic since after giving $\ce{H+}$ to hydrazine results in $\ce{H3N+-NH2}$, and accommodation of the lone…
Rohinb97
- 921
- 3
- 9
- 21
15
votes
2 answers
Heats of combustion and stability of rings
Which isomer would have the largest heat of combustion?
A) Propylcyclopropane
B) Ethylcyclobutane
C) Methylcyclopentane
D) Cyclohexane
E) Since they are all isomers, all would have the same heat of combustion.
Can anyone explain why?
If you think…
yolo123
- 1,845
- 3
- 23
- 39