Lanthanum

Lanthanum tarnishes slowly in air, and burns readily, forming lanthanum(III) oxide, La₂O₃ and lanthanum(III) nitride, LaN, at 450 °C [5].

4 La(s) + 3 O₂(g) 2 La₂O₃(s)
2 La(s) + N₂(g) 2 LaN(s)

Lanthanum does not react with cold concentrates sulphuric acid [5]. It dissolves readily in dilute acid [5], forming La(III) ions and hydrogen gas, H₂.

2 La(s) + 3 H₂SO₄(aq) 2 La³⁺(aq) + 3 SO₄²⁻(aq) + 3 H₂(g)

Lanthanum reacts with all the halogens, forming the corresponding lanthanum(III) halides.

2 La(s) + 3 F₂(g) 2 LaF₃(s)
2 La(s) + 3 Cl₂(g) 2 LaCl₃(s)
2 La(s) + 3 Br₂(g) 2 LaBr₃(s)
2 La(s) + 3 I₂(g) 2 LaI₃(s)

Lanthanum reacts slowly with cold water, and quickly with hot water [5], forming lanthanum(III) hydroxide, La(OH)₃, and hydrogen gas (H₂).

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

Method - Inductively Coupled Plasma Method US-EPA Series 6000 [4]. A portion of the sample is digested in a combination of acids. The digest is aspirated into an 8,000 K argon plasma where resulting light emission is quantified for 30 elements simultaneously.

Method limit of detection in water = 0.01 mg/L
Method limit of detection in soil = 100 mg/kg