## Chemistry and Chemical Reactivity (9th Edition)

Empirical formula: $Tb_2O_7$ Oxidation number: $+7$ Reaction: $4\ Tb(s)+7\ O_2(g)\rightarrow 2\ Tb_2O_7(s)$
In 100 g of the compound: Tb: $73.945\ g/158.925\ g/mol=0.465\ mol$ O: $26.055\ g/15.999\ g/mol=1.62\ mol$ The ratio of the two: $1.62/0.465=3.50=7/2$ Empirical formula: $Tb_2O_7$ Oxidation number: $0= x\times2-2\times7$ $x=+7$ Reaction: $4\ Tb(s)+7\ O_2(g)\rightarrow 2\ Tb_2O_7(s)$