All Questions
Tagged with formatting or notation
267 questions
23
votes
1
answer
808
views
Structure that breaks InChI
I am currently testing a piece of software that generates the InChI for a given structure. I also want to test error situations as end users will also deliver the mol files that will be used as input ...
- 365
1
vote
1
answer
185
views
Empirical and Molecular Formulae
I'm not a chemist, and nor do I study chemistry so please try to be gentle.
Glucose has the molecular formula $\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$ and the empirical formula $\mathrm{C}\mathrm{H}...
- 113
2
votes
1
answer
391
views
Which ions are accounted for in total and net ionic equations?
There are a number of things I don't understand about ionic equations.
First off, when you do net ionic equations, is it correct that you're only focusing on precipitates? The way I understood it, ...
- 175
8
votes
2
answers
3k
views
Should the 'a' in the acid dissociation constant (Ka or pKa) be capitalised?
In science, the negative logarithm of the acid dissociation constant is denoted $\mathrm{p}K_\mathrm{a}$ or $\mathrm{p}K_\mathrm{A}$ depending on the source (lowercase "a" or uppercase "A"). Since it ...
- 183
0
votes
1
answer
7k
views
What does "Anal. Calcd." stand for written out?
I'm wondering what the abbreviation "Anal. Calcd. stands for exactly. It is put in front of calculated (expected) values for elemental analyses. "Analytically calculated" makes no sense for me, but ...
- 362
4
votes
1
answer
1k
views
What's the convention for the symbols of enthalpies of formation, reaction, etc.?
I frequently encounter two ways of writing enthalpies of some process, e.g. for the enthalpy of formation:
$\Delta_{r} G$ (or $\Delta_{R} G$)
$\Delta G_{r}$ (or $\Delta G_{R}$)
On the IUPAC Gold ...
- 18k
1
vote
1
answer
166
views
What does "/2" in the structure of calcium benzoate mean?
Please see the following figure. This is from the high school chemistry book of my son. He wants to know what does that /2 after $\ce{-COOCa}$ mean.
The book is a non English one. And I have changed ...
- 163
5
votes
3
answers
5k
views
How do we represent a molecule in text form?
How do we represent a molecule in text form?
A molecule, as a computer scientist I see it as a connected graph of atoms. A connected graph means that beginning at any atom, there is a path to any ...
- 159
4
votes
1
answer
4k
views
Notation "5% solution"
What does 5% aqueous solution of glucose mean? Note that it's just 5% and not 5%w/w. Do we assume it to be w/w?
The question is
If the osmotic pressure of 5% aqueous soultion of glucose is $\pi_1$ ...
- 400
1
vote
2
answers
401
views
Significant Figures in almost-scientific notation
For a homework assignment on significant digits, I have to find the number of significant digits in the number $0.40 \times 10^3$. I know that in scientific notation, the number of significant digits ...
- 151
7
votes
2
answers
27k
views
Why is ethanol written as C2H5OH not C2H6O?
This is balanced equation of fermentation of glucose:
$$\ce{C6H12O6(aq) -> 2C2H5OH(aq) + 2CO2(g)}$$
I know that the result of glucose fermentation is ethanol ($\ce{C2H6O}$). What represented in ...
- 289
0
votes
1
answer
60
views
What does $\mathrm{A}_r(\mathrm{H})$ represent when calculating the average natural weight of an elemental atom?
I have a question that explains the weights and abundances of various hydrogen isotopes, and the question concludes by asking to:
Calculate the atomic mass of hydrogen $\mathrm{A}_r(\mathrm{H})$ (...
- 229
5
votes
1
answer
239
views
Surface Functional Groups/Notation
I'm reasonably unfamiliar with chemical notation, and recently I've come across something I'm not sure how to interpret. In this article, the authors refer to the "surface groups" denoted by $\ce{#Ti-...
- 231
1
vote
2
answers
3k
views
Chemical formula of ethanol and other carbon compounds
Should chemical formula of ethanol be written as $\ce{CH3CH2OH}$ or $\ce{C2H5OH}$? And whats the logic behind it? I have seen the former being used more often, so why is ethane represented by $\ce{...
- 63
25
votes
4
answers
246k
views
How do I type a simple chemical equation in Microsoft Word?
How do I type a simple chemical equation in Microsoft Word? I can do subscripts, but long arrows are more difficult. I can't get them to align with the text.
Also, I can't figure out how to put a ...
- 361
44
votes
1
answer
7k
views
Why is methane's molecular formula conventionally "CH₄", while water is "H₂O" (among others)?
While revisiting some of my old notes about the Miller-Urey experiment, I stumbled across the "equation"...
Electricity + $\ce{CH4~/~ NH3~/~H2O~/~CO}$ = Amino Acids
This got me thinking.
...
- 1,752
28
votes
2
answers
2k
views
What does this lambda–sigma notation mean?
I am currently reading the CRC Handbook of Phosphorus-31 Nuclear Magnetic Resonance Data by John C. Tebby (CRC Press, 1991) and on several figures (ex. pages 9 to 14) there is a caption that reads ...
- 1,771