All Questions
44,968
questions
2
votes
2
answers
4k
views
Can we force a reversible reaction in equilibrium to achieve 100% completion?
Can we force a reversible reaction in equilibrium to become a "complete" one? If so, will the equilibrium constant change?
It's said about reversible reactions that they never go to completion & ...
- 357
6
votes
4
answers
2k
views
Thermodynamic properties software
I am looking for a software (can be freeware or purchased) to look up water and steam thermodynamic properties (e.g. density, enthalpy, entropy) preferably a macro in excel. What do you use for this ...
- 161
3
votes
3
answers
2k
views
Why are enantiomeric excess % and specific rotation considered?
I was wondering, when working in a lab in an area related to organic compounds, when and why would a chemist consider the enantiomeric excess % and how would a chemist used that information?? Same ...
- 45
1
vote
1
answer
2k
views
What is buffer capacity and how can a buffer "run out"?
I'm a little confused on something:
A buffer has a certain capacity and then runs out.
But, if the buffer is given by: $$\ce{A- + H2O <=> HA + OH-},$$ when the $\ce{A-}$ reacts with the water, ...
- 205
9
votes
1
answer
3k
views
Why is it that weak bases usually contain nitrogen?
Why do weak bases usually contain nitrogen? I know there are two electrons on top for a bond of $\ce{H}$ but why is it mostly nitrogen? I know there are other elemental bases too but why do I keep ...
- 3,050
2
votes
1
answer
1k
views
Dialkylation reactions
In the synthesis of ethyl 2-benzyl-2-methyl-3-oxobutanoate, is the nucleophilic substituion of a benzyl (chloride) group an Sn1 reaction?
The experiment is conducted in ethanol (protic) and is under ...
- 641
4
votes
1
answer
12k
views
How does an ice bath change the rate of an reaction?
If I had hydrogen peroxide decompose with the help of manganese dioxide and measured the time taken for the reaction to complete and the volume of oxygen collected. I will get a graph that looks like ...
- 41
0
votes
1
answer
492
views
How to get a "rechargable" chemical reaction for a glow stick
I want to create my own glow stick that lasts a while while ligting up the surroundings. How would I go about this? I know there are youtube videos and such. But the way they do it doesn't allow for ...
- 103
2
votes
1
answer
536
views
Clarifications about acid-base theory [closed]
Considering the Arrhenius theory of acids and bases:
Is every existing compound either an acid or a base?
Why is a compound such as $ \ce {NH_3}$ considered a base, if it doesn't even have an ...
- 172
9
votes
1
answer
45k
views
How to know it when I see a covalent network?
This is a well-known (better said: well-discussed) question in the internet. When you look for answers for popular questions, you usually see them with a variable degree of reliability and complexity. ...
- 10.6k
2
votes
1
answer
422
views
Determine most electronegative element based on successive ionization energy data
X, Y and Z are three unknown elements whose first 5 ionization energies are given below. Which of the 3 is the most electronegative?$$
\begin{array}{|c|c|c|c|c|c|}\hline
&\text{IE}_1&\text{IE}...
- 267
9
votes
2
answers
385
views
Lifetime measurement: double peak in instrument response function
I am measuring flourescence lifetimes with a picosecond pulse laser, using the LifeSpec II with an MCP detector. Instead of a single peak rapidly decaying, as would be expected, my IRF contains two ...
- 521
5
votes
1
answer
10k
views
Why does the phosphorus trifluoride molecule have dipole moment?
My book says that from drawing the Lewis structure for the molecule below, you can conclude that it has dipole moment. Can someone please explain why?
I understand that the dipole moment expresses ...
- 267
5
votes
1
answer
5k
views
What is 'Retention period' in chromatography and what is its importance?
I heard people quite often speak about retention time/retention period in Chromatography and Mass Spectrometry. I see somewhere that it is the time duration between the injection time and the target ...
- 243
21
votes
3
answers
42k
views
Oxidation state of the sulfur atoms in the thiosulfate Ion
What are the oxidation states of the two inequivalent sulfur atoms of the $\ce{S2O3^{2-}}$ molecule? For all I know is that Lewis Structure does matter in most of the cases.
- 2,175
3
votes
2
answers
2k
views
Can artificial sea water be prepared by mixing sea salt with water?
I am looking for ways to easily prepare artificial sea water. The chemical composition doesn't have to exactly match that of natural sea water. On-line I can find recipes to prepare sea water. But I ...
- 31
2
votes
1
answer
2k
views
Why don't ions have one equilibrium potential? (Nernst equation)
I know that equilibrium potentials are dependent on the ratio of ion concentrations inside and outside of the cell and temperature. I also know that the equilibrium potential is reached when there is ...
- 56
1
vote
1
answer
455
views
Helium gas expand isobaric isothermal
If $4\ \mathrm{mol}$ helium gas expand against constant pressure in isothermal process, how can calculate $W$?
Is it $W=-nRT\ln\frac{V_2}{V_1}$ as defined by isothermal or is it $W=-p\left(V_2-V_1\...
- 31
4
votes
1
answer
4k
views
What is the difference between the Joule and Joule–Thomson coefficients?
Is there a difference between the Joule coefficient and the Joule–Thomson coefficient? Also, I am having a hard time understanding what they mean.
- 73
10
votes
5
answers
50k
views
What's the pH of vinegar containg 5% acetic acid?
Vinegar generally contains 5% acetic acid. We would expect the pH of vinegar to be approximately:
a. 0
b. 3
c. 7
d. 9
e. 12
I don't have the key for this question, so I just want to make ...
- 3,050
2
votes
2
answers
309
views
How to calculate a rough estimate for the volume of a nitric oxide molecule?
I was wondering what would be the best way to calculate a rough estimate for size of a nitric oxide molecule to use in comparison to a box.
I was thinking volume would be the best method, but this ...
- 21
3
votes
1
answer
706
views
Reason for inconsistency in specific gravity of calcium choride added to water
I am seeing a significant change in specific gravity of products upon addition of $\ce{CaCl2}$ to water. The mass and volume of what goes in doesn't match my total specific gravity of what comes out. ...
- 43
4
votes
1
answer
1k
views
Why did they provide the value for the enthalpy change of fusion?
The metal gallium melts when held in the hand; its melting point is $\pu{29.76 ^\circ C}$. How much energy as heat is removed from the hand when $\pu{5.00 grams}$ of gallium initially at $\pu{20.0^\...
- 387
4
votes
1
answer
1k
views
Which chemical reactions occur between my tongue and the food I eat?
There are various chemical reactions that can occur between materials.
Which chemical reactions occur with the tongue?
How come all reactions are reversible (nothing sticks to my tongue)?
What's ...
- 4,257
14
votes
1
answer
1k
views
Do molecules with axial chirality have "stereogenic units"?
This question is a follow-up to a recent question on discodermolide stereochemistry that I answered here. In the course of reading IUPAC's definition of "stereogenic center", I wondered if axially ...
- 21.9k
-9
votes
1
answer
917
views
Reaction between elements in a periodic table [closed]
Can we know the reaction between any two elements in the periodic table? If yes then can we know the reaction between any three or more elements in the periodic table?
- 101
1
vote
1
answer
565
views
MO scheme for coordination complexes (tetrahedral) - Heteroligand vs. homoligand
How is the MO diagram drawn for a tetrahedral complex with heteroligands (e.g. $\ce{[NiCl2(PPh3)2]}$) different from a tetrahedral complex with the same type of ligand? Do we consider the same "a1 and ...
- 517
6
votes
2
answers
3k
views
Mimic a volcano eruption with household chemicals?
How can one mimic a volcano eruption using household chemicals safely?
We've tried it in a testing tube with baking soda and vinegar. This wasn't quite as impressive as expected.
On the web we've ...
- 163
3
votes
1
answer
4k
views
How does zinc become oxidized when it's not in direct contact with copper ions in a galvanic cell?
Whenever a galvanic cell is explained in textbooks/videos, it usually starts by showing that if you put a piece of $\ce{Zn}$ in a $\ce{Cu^{2+}}$ ion solution, the $\ce{Zn}$ will become oxidized and ...
3
votes
2
answers
2k
views
What is hard and soft water and how does the process of dissolution work?
This is a very basic question about solubility, especially solution of table salt in water and solution of sugar in water. I have heard about terms like hard water, soft water, filtering of water to ...
- 31
4
votes
1
answer
5k
views
How many stereogenic centres are there in discodermolide? [closed]
It is generally said that carbon-carbon double bonds cannot behave as stereogenic centres but the above molecule contains three such centres. Can somebody please point out all the stereogenic centres (...
13
votes
3
answers
4k
views
On the stability of deuterium
The isotope of hydrogen, tritium, is indeed radioactive resulting in $\ce{^3He}$ through beta decay.
But what of the radioactively 'stable' isotope deuterium?
Are all deuterium atoms destined to be ...
- 2,773
9
votes
2
answers
4k
views
Why do copper (II) complexes contain so many valence electrons?
Consider tetraaminecopper (II) ion. $\ce{[Cu(NH3)4]^2+}$ or $\ce{[Cu(NH3)4(H2O)2]^2+}$.
The copper(II) ion has the electron configuration $\mathrm{[Ar]\ 3d^9}$. How do the 4 electron pairs from the ...
- 191
1
vote
0
answers
44
views
Gas-Phase Functionalization of Carbon Nanotubes
I'm new to the subject of carbon nanotubes; However, I recently studied a little about them. But I failed to understand the gas phase functionalization.
As I understand, this technique is used to ...
- 111
0
votes
1
answer
968
views
Why does the potential difference of a current drop, when silver nitrate is added to deionised water?
Semi-related to Why do some salt ions in solution conduct electricity better than others?
After conducting more experiments, using deionised water as an analyte only, I found the potential difference ...
- 265
13
votes
4
answers
34k
views
Which orbitals of the hydrogen atom are degenerate for n=3?
Which of the following orbitals are degenerate in the hydrogen atom with $n = 3$?
A. II and III only;
B. I and IV only;
C. I, II, and IV only;
D. II, III, and IV only;
E. all.
The ...
- 133
2
votes
1
answer
297
views
Hydrolysing large molecules to reveal amino acids
Consider Oxytocin:
I am asked to hydrolyze Oxytocin and reveal 5 amino acids which are the result of this hydrolysis.
I must admit I have no idea where to begin. I know that generally amino acids ...
- 703
3
votes
1
answer
3k
views
n-factor for ammonium nitrite?
The given reaction is $$\ce{NH4NO2 \rightarrow N2 + 2H2O}$$
The way I did it was
$$\ce{NH4+ \rightarrow \frac{1}{2} N2 + 4H+ + 3e-}$$
and
$$\ce{NO2- +3e- +4H+ \rightarrow \frac{1}{2} N2 + 2H2O}$$
...
- 31
2
votes
1
answer
59
views
Oxide surfaces develop a charge in H2O. Do we have any, even vague, handle on how long does an indivdual charge last on avg. before being neutralised?
We often know, from e.g. titration experiments, what the average surface charge density of a surface is.
How do these charges vary over both time and space (i.e. dynamics)? I have been unable to find ...
- 21
2
votes
0
answers
355
views
Equivalent points for 3 fold and 6 fold symmetry
In a crystal Lattice how to find the equivalent points for 3 fold and 6 fold symmetry?
- 21
4
votes
1
answer
5k
views
What are examples of group 14 elements forming dπ - pπ bonding?
While studying the Group 14 elements, I came across the anomalous behaviour of carbon. In that there was a point:
Carbon forms only p$\pi$-p$\pi$ type bonding while other elements in the group form ...
- 178
13
votes
2
answers
59k
views
Hardy Schulze law
I have trouble understanding this particular law.
It states that:
Greater the valency of the flocculating ion, greater will be its coagulation power.
Why does this happen? What is the intuition ...
- 395
10
votes
2
answers
8k
views
Are all solutions of weak acid/bases buffers?
I am having a difficult time understanding what makes a buffer a buffer.
Buffers in my textbook are defined as a solution of a weak acid or base and their conjugate acid/base. So if I were to just ...
- 349
3
votes
1
answer
150
views
What is the direction of charge transfer between Aluminum and aliphatic amines physisorbed on top?
Is there dipole formation upon physisorption of an aliphatic amine to an aluminum substrate? What is the charge transfer direction? What if the aluminum substrate is clean, surface oxidized or covered ...
- 81
4
votes
2
answers
4k
views
What is the dipole moment direction of an aliphatic amine, i.e., R-NH2?
Since the electron donating property of $\ce{N}$ and $\ce{C}$ is different, there is partial charge transfer between $\ce{N}$ and $\ce{C}$ atoms in aliphatic amines, namely $\ce{R-NH2}$. What is the ...
- 81
1
vote
2
answers
1k
views
Rate of Reaction Graph - Gas Produced
I did a reaction and I measured the volume of gas produced against time. I need to find the rate constant of the reaction.
I am trying to plot a graph of ln(vol of gas produced) against time so that ...
- 41
3
votes
1
answer
3k
views
Calibration Curve Error Propagation
I am using ED-XRF for geochemical analysis for a geology dissertation. The ED-XRF provides a ppm reading for elements and a 2sigma error, for example 472 +- 5.11ppm Sr.
An example calibration ...
3
votes
2
answers
11k
views
Are Na and Cl ions from NaCl in water separate charged particles?
Suppose I pour some sodium chlorine into water. So, what happens is that
$$
\ce{NaCl (s) -> Na+ (aq) + Cl- (aq)}
$$
meaning that the ionic bond between Na and Cl breaks up (correct this far?)
...
- 55
2
votes
2
answers
737
views
Why does (atmospheric) pressure have an effect on solubility?
The Wikipedia article titled Solubility table states that
The table below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with ...
- 55
6
votes
1
answer
2k
views
Thionyl Chloride and enols, carboxylic acids, alcohols
\begin{align}
\ce{Propanol + SOCl2 &-> Expected~ alkyl~ halide~ product}\\
\ce{Propanoic~ acid + SOCl2 &-> Expected ~acid ~chloride ~product}\\
\ce{Acetone ~enol + SOCl2 &-> doesn'...
- 18.8k