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How many of the following will evolve $\ce{H2}$ gas when dissolved in water under room conditions?

$\ce{B2H6},$ $\ce{SiH4},$ $\ce{CH4},$ $\ce{Al},$ $\ce{B},$ $\ce{Na},$ $\ce{PCl3},$ $\ce{P(white)},$ $\ce{Fe}.$

Initially, it seemed easy to me and I got 7 (all except $\ce{PCl3},$ $\ce{CH4}).$ Correct me if I am wrong here.

However, the answer given was 3, which given were most likely $\ce{B2H6},$ $\ce{SiH4}$ and $\ce{Na}.$

What did I do wrong here? Does the temperature condition hold that much difference here? How do you predict products like these?

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    $\begingroup$ Hi Storm CR, please visit this page, this page and this one on how to format your future posts better with MathJax and Markdown. $\endgroup$
    – Zenix
    Commented May 23, 2020 at 6:45
  • $\begingroup$ I have visited them,How do you expect me to make this post better.It would be very much appreciated if you could tell me what I did wrong there^ $\endgroup$
    – Anand Maneesh
    Commented May 23, 2020 at 6:57

1 Answer 1

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$$\ce{B2H6 + 6H2O -> 2H3BO3 + 6H2 \\ SiH4 + 4H2O -> Si(OH)4 + 4H2 \\ 2Na + 2H2O -> 2NaOH + H2 }$$

The rest do not react with water under ordinary conditions. $\ce{Al, Fe, B}$ react only with steam or when they are red hot. White $\ce{P}$ undergoes easy hydrolysis when coordinated with ruthenium, as illustrated by Vaira et al. [1]. $\ce{CH4}$ does not undergo hydrolysis with water and $\ce{PCl3}$ does not give hydrogen on hydrolysis.

Reference

  1. Vaira, M. D.; Frediani, P.; Seniori Costantini, S.; Peruzzini, M.; Stoppioni, P. Easy Hydrolysis of White Phosphorus Coordinated to Ruthenium. Dalton Transactions 2005, 0 (13), 2234–2236. DOI: 10.1039/B504795A.
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