Why was the question How does ph depend upon temperature closed for lack of details/clarity?

I had no problem understanding the original question, but it was poorly written, so it received downvotes.

I thus edited to it to make it clear. Even after this, it continued to receive downvotes, and thus was ultimately closed for insufficient details/clarity. I don't understand why my edited version was judged to lack these.

I thought I made the question quite clear. And I don't believe it needed any more details to be understandable beyond what I supplied. It's actually a really simple question: Increasing temperature yields two competing effects, and the OP wanted to know which one wins.

The criterion for insufficient details or clarity is: "As it's currently written, it’s hard to tell exactly what you're asking". So, as I've edited it, how is it hard to tell exactly what's being asked?

Granted, I didn't use very sophisticated language in rewriting it β€” I kept it deliberately simple β€” to try to stay true to the "voice" of the OP. But I don't believe that made it unclear.

Finally, the site explains that one of the purposes of having close votes is to encourage users to edit that question to improve it, so it meets site standards. But what's the point in doing that work if the evaluators are going to close that question anyways for seemingly non-applicable reasons?


Thanks for everyone's comments and explanations. It helps to understand the thinking that underlies these close votes.

I. A couple of responders said they viewed the question as lazy b/c the OP didn't put in any effort on his own. I would say there are two aspects to effort:

1) Coming up with the question. 2) Trying to answer the question.

With this question, I acknowledge there was no effort made with respect to #2. But the reason I decided to answer it anyways is because there was effort with respect to #1.

Most student questions on this site aren't novel -- they're from students having the usual confusion about the subject. This question was different -- it was from someone who was putting effort into going beyond the standard material (relative to his or her level). I.e., rather than just accepting that [H+] increases with T in pure water, s/he noted that water (yes, above 4C) expands with T, and that this expansion would tend to reduce concentration. I.e., it was from someone who was trying to put effort into thinking more deeply about the subject, rather than just the usual, "this doesn't make sense to me, can you help me understand it..."

That's why I decided to reward it with an answer, in spite of the lack of post-question research effort. And that's why I think this puts the OP's effort into a gray area.

II. Some responders mentioned they thought not specifying constant-p, and T>4C, made the question unclear. I think those are red herrings. I think it was implicit in the question that those were the conditions, since the OP was referring to a regime in which water did expand with T, and in which water could expand.

Given this, I don't think their absence made the question less clear; rather, it made it less technically precise. If I were writing the question myself, I would have specified the conditions precisely; but it wasn't my question, it was a student's question, and some latitude needs to be given for a lack of technical precision. And as I said, I tried to rewrite it in that student's "voice". I believe that, if the student knew enough to specify the conditions that precisely, the student would have been at a level where s/he wouldn't have needed to ask that question in the first place.

To give a concrete example, there are several questions on the site about the van 't Hoff equation and $\Delta$H. Many of them don't explicitly specify that the reaction conditions are constant T and p (which are needed for the van 't Hoff equation to be valid), and I'd be surprised if more than a very few also specified that the system is closed (another necessary condition, which I might not bother to specify myself, since this is implicit from the fact that we're talking about equilibrium). Does this mean the question is unclear?

Finally, I suspect if you went back through questions to which you yourself have given answers, you will sometimes see an equivalent lack of precision in specification of conditions (indeed, I often find that those answering questions don't precisely specify conditions).

  • 1
    $\begingroup$ It seems clear enough to me. I would be in favour of reopening. $\endgroup$ – orthocresol May 31 '20 at 2:05
  • $\begingroup$ You are right, the OP did put some thought into the matter, and their question is representative of a classic problem we encounter when learning in courses or during research, namely disentangling the importance of different causes of change. Basic (and usually ideal) theories don't always convey which are the most important factors behind some change. $\endgroup$ – Buck Thorn Jun 1 '20 at 5:56

First off, thank you for taking your time and improving the question as well as raising the issue on Meta. I also agree with Buck's answer in many aspects. Judging from the timeline, the following happened:

  1. Three votes suggesting that the question needs details or clarity.
  2. Question edited by theorist.
  3. One vote to close the question as homework.
  4. I voted to close the question as unclear.

I guess nobody is surprised to the three votes (1) raised prior to the edit (2):

How does ph depend upon temperature

We know that ph is inversly proportional to molar conc.of H+ions ..we also know that as temperature increases no. Of water molecules dissociating will increase as well the volume will also increase ...what would be the net effect on [H+]

I can see how it still could be closed as homework (3) due to the questionable amount of research process OP invested in posting the question. The temperature dependencies for both the ionic product and volume of water are easily available, e.g. here and there, respectively (I literally took the first search results from Google). OP, however, decided to go with "as we all know" phrase usually used to convince the audience in the absence of proven facts which there were plenty, so I guess it's just laziness.

Now, after giving the edited question a thoughtful read, I admit that my decision (4) was rushed out and doesn't really reflect the issue after the edit. I would say it was very much was affected by the abysmal appearance (not the idea behind) of the original question (which I saw in the review queue and skipped at first β€” I didn't got what it was about at first glance at all), as well as remaining issues like a single paragraph with the hard-to-follow logic or "ph" in title (reads as "picohour"). The prevalence of the existing votes might have also played its role (herd instinct).

Long story short, I agree that the question can be reopened after the remaining problems are sorted out. On the other hand, I left a link to this topic below the question so that OP could familiarize themselves with how to avoid such situation in the future.

  • $\begingroup$ I added an addendum to explain my thinking on the laziness issue. $\endgroup$ – theorist Jun 1 '20 at 0:02

I voted to close. In retrospect it was likely a reaction to the general lazy quality of the question, starting with "We know that ..." without providing any references or additional information. In fact from the melting point up to a temperature of ~$\pu{4^\circ C}$ at standard pressure the volume of liquid water contracts, so the statement that the volume increases is not generally true.

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    $\begingroup$ I should add that @theorist made extensive edits to the original low quality post. I tried to determine from inspection of the timeline whether I voted to close before or after theorist made those edits, but couldn't tell. In any case, my original point stands, it might have been a bit of a knee-jerk close reaction, but then the OP had a haphazard quality to it. $\endgroup$ – Buck Thorn May 31 '20 at 9:22
  • $\begingroup$ I added an addendum to explain my thinking on the laziness and condition-specification issues. $\endgroup$ – theorist Jun 1 '20 at 0:01

I voted to close. I am almost certain it was before the question was extensively edited.

That said, it still remains murky for me.

My takeaway is that the OP is stating that increasing the temperature water results in both increasing the concentration of $\ce H^+$ and increasing the volume of the water in question.

I have to assume that the system is at constant pressure - and not constant volume - in order to take a stab at this. That's problem #1.

Problem #2 has been identified by Buck Thorn in this thread, and means I can't presume that this question applies for all segments of the relevant part(s) of the phase diagram for water.

Problem #3 - assuming #1 and #2 are clarified or dodged by specifying a "safe" set of pressure, temperature, and other assumptions - is that I'm not sure one can quantify the dominant cause and effect relationship being asked.

In summary, I am comfortable with keeping the question closed.

  • $\begingroup$ I added an addendum to explain my thinking on the laziness and condition-specification issues. $\endgroup$ – theorist Jun 1 '20 at 0:03

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