Laboratory Preparation of Dihydrogen

Laboratory Methods

Dihydrogen is conveniently generated in the lab in two simple ways:

1. Zinc with dilute acid. Granulated zinc reacts with dilute hydrochloric acid, displacing hydrogen gas:

2. Zinc with aqueous alkali. Zinc is amphoteric, so it also reacts with aqueous sodium hydroxide, forming soluble sodium zincate and releasing hydrogen:

$Zn + 2NaOH \rightarrow Na_2ZnO_2\ (\text{sodium zincate}) + H_2$ …