Praseodymium

Praseodymium dissolves readily in dilute sulphuric acid, forming a green solution of Pr(III) ions and hydrogen gas, H₂.

2 Pr(s) + 3 H₂SO₄(aq) 2 Pr³⁺(aq) + 3 SO₄²⁻(aq) + H₂(g)

Praseodymium reacts slowly with oxygen, O₂, tarnishing the surface, under normal conditions. Praseodymium can be burned, thereby oxidizing to a mixture of praseodymium oxides with the approximate formula Pr₆O₁₁:

12 Pr(s) + 11 O₂(g) 2 Pr₆O₁₁(s)

Praseodymium reacts with the halogens, forming the corresponding praseodymium(III) halides.

2 Pr(s) + 3 F₂(g) 2 PrF₃(s) [green]
2 Pr(s) + 3 Cl₂(g) 2 PrCl₃(s) [green]
2 Pr(s) + 3 Br₂(g) 2 PrBr₃(s) [green]
2 Pr(s) + 3 I₂(g) 2 PrI₃(s)

Praseodymium reacts slowly with cold water, and quite quickly with hot water, forming praseodymium hydroxide, Pr(OH)₃, and hydrogen gas (H₂).

2 Pr(s) + 6 H₂O(l) 2 Pr(OH)₃(aq) + 3 H₂(g)