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Should we allow questions of the form "what's the <numerical value> of <compound>"?

Eg: Is the specific heat capacity of liquid iron constant?

I say they are too localized and not conceptual. Community opinion?

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    $\begingroup$ Note that the particular example isn't valid here--he isn't really asking for data, he's asking for something else. $\endgroup$ – ManishEarth May 23 '12 at 19:00
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    $\begingroup$ One difficult task is sometimes to find where appropriate data can be found, which is not always obvious or well referenced. I agree it is pointless to copy the values from the "Handbook of Chemistry & Physics", but sometimes finding relevant values is really a difficult task and might require some expert help. $\endgroup$ – PLD May 23 '12 at 20:54
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    $\begingroup$ @PLD One solution to that might be a Community Wiki question/answer that list good places to find such values and MSDSes and so on. $\endgroup$ – Matthew Read Jul 10 '12 at 17:52
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In my imagination, there are only a few reasons why one would think of asking that type of question:

  • It is a homework assignment, so basic homework rules should apply;
  • It is part of a person’s research work in which case they should know how to look up stuff;
  • Someone is trying to write up an exercise and needs a realistic value. But that means that they are teaching somebody and should have learnt how to teach which is commonly done at universities where you learn how to research, too.

So all things considered, I don’t think that there is a valid, lasting value in these questions, that they all kind of fit a pretty broad homework-ish definition and therefore should be treated as such: Usually closure.

NB: There are so many free online databases that a Google search should provide the answer anyway.

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These days, Google tends to provide at the least a starting point for most 'what is the value' questions. For example, Googling 'specific heat capacity of liquid iron' returns first of all the Chemistry SE question listed (!), and the second hit is to the NIST database which has the answer. I don't think Chemistry SE aspires to having a complete listing of all material properties, so these questions should not be on topic.

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I think there is one more use-case when data-question may occur: the person simply doesn't have access to the data.

Personally, I faced two situations when I actually needed to ask for the data in one form or the other:

  1. The data is behind a paywall. This mostly includes the information from the recent papers and various information stored in databases (CCDC, Reaxys, etc.).
  2. The data is very specific. Datasheets for various analytical devices, calibration plots, manuals and regulations are often very hard to find. This is especially true for old devices and analytical methods developed for a specific manufacturing process.

Both cases are poorly covered by Google Search, as the data may not even be present on the web, or have very limited access.

Surely one should avoid doing obvious info-requests, but I would still allow and welcome questions where non-trivial data-mining is necessary, and it is clear that the person physically cannot help himself.

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  • $\begingroup$ I can see why in such case help would be needed, but both aren't exactly useful for other people then OP. Don't seem to be good for making a question on main site. Behind paywall could be helped in chat though. $\endgroup$ – Mithoron Jul 30 '17 at 19:59
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    $\begingroup$ @Mithoron Helping one person is good enough for me, and one can never say for sure who and when can face the same problem again. I don't know how chats logs on SE-sites are indexed and for long they are stored, but something tells me they have lower availability over time than the Q&A section. $\endgroup$ – andselisk Jul 30 '17 at 20:14
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TL;DR Such questions are not on-topic for Chemistry Stack Exchange.


For the last few months, I've been closing such questions as off-topic > custom >

I'm closing this question as off-topic as requests for specific data points are not suitable for Chem.SE.

or some variation thereof. I have yet to encounter any opposition. I think it does not make sense to allow them, as we then have to allow questions about all chemicals and all their properties, and that is rather ridiculous.

I believe that at some point we should also update the relevant help centre page (namely /help/on-topic), maybe I will get round to it soon.

If people want to help the asker (e.g. if they have access to a particular resource that has the desired data), they can always leave a comment, and I don't discourage anybody from doing so.

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