I was writing chemical reaction using mychemistry package. I have a problem with \chemand which produces [0pt]+ as output in pdflatex. How can I get rid of the [0pt]?

\arrow[,,1.50]{\scriptsize Pt on}{\scriptsize \ch{Al2O3xH2O}}

enter image description here

  • The mychemistry package is classified as obsolete by its author. The wrong output is due to an internally called \chemsign macro that's not defined any longer. – egreg Nov 13 '17 at 9:02
  • As commented above the package is obsolete and should not be used. If you do want to use it, then for this specific issue you can add \newcommand{\chemsign}[2][]{#2} below \usepackage{mychemistry} which will output a (somewhat misaligned) + sign for the MWE. – Marijn Nov 13 '17 at 10:17
  • Thank you very much. I usually use mhchem package to write simple chemical reactions and did not know that mychemistry package is obsolete ! I think I better use chemfig as Mr. Clemens suggested. – Jeffrey Nov 14 '17 at 11:58

The mychemistry package is obsolete and not updated any longer (the last update was nearly 5 years ago). It used to have its purposes before v1.0 of chemfig was published on 2011/06/15. Since v1.0 chemfig comes with a built-in mechanism for reaction schemes.

mychemistry used to build upon chemfig which means it also uses commands provided by chemfig. chemfig used to have a command called \chemsign until v1.2 (2015/10/08). chemfig itself removed this command in favor of its more advanced scheme mechanism.

The scheme from the OP without mychemistry:




    \arrow{->[\scriptsize Pt on][\scriptsize \ch{Al2O3xH2O}]}[,2]
    \ch{3 H2}


enter image description here

  • Oh thank you Sir !! I didn't know that the package became obsolete. Thanks for your explanation and correction. It works now ! – Jeffrey Nov 14 '17 at 11:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.