Reaction of lanthanum with air
Lanthanum tarnishes slowly in air, and burns readily, forming lanthanum(III) oxide, La2O3 and lanthanum(III) nitride, LaN, at 450 °C .
4 La(s) + 3 O2(g) 2 La2O3(s)
2 La(s) + N2(g) 2 LaN(s)
Reaction of lanthanum with acids
Lanthanum does not react with cold concentrates sulphuric acid . It dissolves readily in dilute acid , forming La(III) ions and hydrogen gas, H2.
2 La(s) + 3 H2SO4(aq) 2 La3+(aq) + 3 SO42−(aq) + 3 H2(g)
Reaction of lanthanum with halogens
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)
Reaction of lanthanum with water
Lanthanum reacts slowly with cold water, and quickly with hot water , 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 . 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