Question

How would you prepare dihydrogen gas from (i) acid (ii) alkali.

Answer 1

i )From acids

For preparation of hydrogen from acids like HCl,H2SO4 etc,we mostly use s block elements like Na,Li,K etc.

Example:-

2HCl + 2Na-—→2NaCl +H2

This reaction followed by substitution reaction gives out effervescence of hydrogen gas.

ii ) from alkalis

Metals like Be, Zn, Sn react with boiling alkali solution liberating dihydrogen.

Be + 2NaOH ———–> Na2BeO2 + H2

Zn + 2NaOH ———–> Na2ZnO2 + H2

Sn + 2NaOH + H2O———–> Na2SnO3 + H2

2Al + 2NaOH + 2H2O ———-> 2NaAlO2 + 3H2

Answer 2

By reacting them with a metal

For eg

2Zn+2HCl---->2ZnCl+H2O