Wikidata:Property proposal/formula weight
formula weight
[edit]Originally proposed at Wikidata:Property proposal/Natural science
| Description | molar mass of an empirical forumula unit of a chemical compound, element or isotope |
|---|---|
| Represents | formula weight (Q3900742) |
| Data type | Number (not available yet) |
| Example 1 | C₁₅H₂₀O₄ (Q129998552) => 264.13615911 |
| Example 2 | sodium chloride (Q2314) => 57.959 (may be unnecessary once we have Wikidata:Property proposal/chemical formula) |
| Example 3 | Phosphorus pentoxide (Q369309) => 283.9 (P2O5) and 567.8 (P4O10) |
| Example 4 | chlorine (Q688) => 35.45±0.01 |
| Example 5 | uranium-238 (Q1148503) => 238.050786996±0.000001602 |
Motivation
[edit]Currently we use mass (P2067) for molar mass of a chemical compound (for individual items about compound). This is problematic for the following reasons:
- Many compounds does not contain individual molecules, such as sodium chloride (Q2314) so describing "mass" of sodium chloride (Q2314) is semantically incorrect.
- We currently uses different units for molar mass including dalton (Q483261) and gram per mole (Q28924752). To be consistent we does not use a unit in this property.
- In addition gram per mole (Q28924752) is not a mass unit - so it will be bad to put such unit to mass (P2067)
- See also Wikidata:Property proposal/chemical formula: a compound can have multiple formulas (e.g. Phosphorus pentoxide (Q369309) can be P2O5 or P4O10). So "mass" of some compound does not has well-defined meaning.
So I propose to split "formula weight" of a compound to a new property that does not use unit.--GZWDer (talk) 21:07, 28 August 2024 (UTC)
Discussion
[edit]
Weak oppose (1) formula weight is an outdated term, AFAIK relative molar mass is the correct one. (2) molar mass unit was rightly removed from mass (P2067) some time ago (now I saw it has been restored, which I just fixed, because different units should not be mixed in one property), (3) dalton (Q483261) is not a unit of molar mass and we don't have molar masses in our items right now, (4) whether we will have a relative molar mass without a unit or a molar mass with a unit – it has no practical significance as long as it is consistently observed within the property, (5) the most important problem, which has not been mentioned in any aspect, and which at this point prevents any use in any way of the masses of chemical entities that we already have – for each chemical entity, the mass can be calculated in many ways: as the mass taking into account the natural abundance, or the monoisotopic mass. The lack of appropriate qualifiers defining the method of calculation of the mass prevents the use of such mass and will prevent such use whether we create one new property or 10. Like the proposal regarding chemical formulae, this proposal is published too quickly and there was no prior discussion of the problem, e.g. in the WikiProject Chemistry. In my opinion, the discussion here will not enable us to develop an appropriate solution, and the proposal itself in its current form does not solve the most important problem that we currently have. Wostr (talk) 22:39, 28 August 2024 (UTC) Pinging user:Preimage as you participated in this discussion. Wostr (talk) 22:42, 28 August 2024 (UTC)
- Linking also Wikidata_talk:WikiProject_Chemistry/Archive/2018#(Molar?)_mass_of_compounds. Wostr (talk) 22:42, 28 August 2024 (UTC)
Not done, no consensus of proposed property at this time based on the above discussion. Regards, ZI Jony (Talk) 18:50, 16 September 2024 (UTC)
Weak oppose until it gets my full 
Support.- I see this proposal as beneficial and an opportunity to improve the current not so ok way we model chemical entities "masses".
- Yes, we should decide if going for monoisotopic mass, natural abundance, etc. I think we can together shape this proposal in order to fix these aspects. I also agree that formula weight is outdated and we should rather use another term.
- What is missing in the proposal:
- - A qualifier with the calculation method?
- - I hardly see references available? ("stated in PubChem" seems suboptimal)
- - Does it really want to apply to chemical entities and not the formulas? So that, for consistency, we will have to check and maintain the same number 1,000+ times instead of 1 in some cases? (https://w.wiki/B2ax)
- I do not have all the answers but would love to start building consensus on these aspects. AdrianoRutz (talk) 07:33, 24 September 2024 (UTC)
