Suppose I've discovered something that I think will be useful for others. But I don't have a question, I just want to share it. Can I post that on Chemistry Stack Exchange? Do I have to do it in a "question-and-answer" format, even if I never had an actual question?
The specific thing I found was that there are several "pH value calculator" widgets available online, and virtually all of them (8 out of 9) give the wrong answer when calculating the pH of an $\ce{H2SO4}$ solution. This is because they all assume that sulfuric acid donates only the first proton, but they don't take into account that it's a polyprotic acid and that some of the molecules donate a second proton as well. So they tend to give higher than correct pH values (that is, underestimate the number of protons in solution).
Here are the ones I found. For all of them, if you attempt to calculate the pH of an $\ce{H2SO4}$ solution at $\pu{0.001 M}$, they give the answer as $3$, although the answer from reference is $2.75$:
- wolframalpha.com
- https://sensorex.com/ph-calculator/
- http://www.endmemo.com/chem/phcal.php
- https://calculator.tutorvista.com/pH-calculator.html
- https://www.webqc.org/phsolver.php
- http://calistry.org/calculate/pH-strong-acid
- https://byjus.com/ph-calculator/
- https://www.thermidaire.on.ca/pc.html
and, drum roll, the only one that got it right: