I have always been confused about the role of slash in chemical reactions.

In some reactions, e.g. $\ce{NaBH4}/\ce{OH-}$ it means we use both compounds, right?

And in reactions where we write $\ce{Pt/Pd/Ni}$ do we mean platinum or palladium or nickel?

  • 2
    $\begingroup$ Usually in a reaction slash means both. H2, Pd/C is the prime example. If it's in a sentence, i.e. plain text, I'd say it probably means or, although context is important as well. $\endgroup$ Nov 30, 2015 at 14:52
  • $\begingroup$ I always thought the everyday meaning is implied and it seems to have been a correct assumption every time. $\endgroup$
    – M.A.R.
    Nov 30, 2015 at 21:00
  • $\begingroup$ I'm not aware of the standard, but the textbook usually specifies it above the reaction when it is first mentioned. It would be useful to have convention. $\endgroup$
    – tkhanna42
    Dec 1, 2015 at 12:27

2 Answers 2


The ambiguity seems to come not so much from Chemistry, but from English punctuation. Slashes are often used in place of "and", "or", or the latin "cum" (meaning combined with). It seems that it unfortunately is just context dependent, though I would argue its use as a replacement for "or" is most consistent grammatically and defining this to be the meaning of the slash would eliminate ambiguity in these situations.


The "/" mainly means the medium in which the compound is present. NaBH4/OH- means NaBH4 is being used in basic medium. After all the medium in which a particular compound is present matters much in a chemical reaction. Similarly, Pt/Pd/Ni (which is commonly used when H2 is a reactant) implies H2 is being passed over any of the above 3 metals (which help to dissociate H2 into [H] atoms to help in reaction).

  • 1
    $\begingroup$ The two uses of '/' that you are describing seem to be completely different, not similar. $\endgroup$
    – bon
    Dec 3, 2015 at 18:30
  • $\begingroup$ Agree with bon...in the first example of yours / plays role of and in 2nd it plays role of or..this is exactly my confusion $\endgroup$
    – geek101
    Dec 4, 2015 at 14:31

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