Question

Explain the reaction of lanthanoids with the following: 

i. Mineral acids 

ii. Water 

iii. Sulphur 

iv. Hydrogen

Answer 1

i. Reaction with mineral acids: Reaction with mineral acids, liberates H2 gas as they have reduction potential of -2.0 to -2.4 V

2Ln + 6HCl → 2LnCl₃ + 3H₂

ii. Reaction with water: Reaction with water, forms ionic and basic lanthanide hydroxides with liberation of H₂ gas.

Ln + 3H₂O → Ln(OH)₃ + 3H₂

iii. Reaction with sulphur: Reaction with sulphur, forms lanthanide sulphide (Ln₂S₃).

2Ln + 3S → Ln₂S₃

iv. Reaction with hydrogen: The metals combine with hydrogen when gently heated in the hydrogen gas.

4Ln + 3H₂  2LnH₃