# What is the mass, in grams, of 2.50 moles of iron(II) hydroxide, Fe(OH)_2?

The mass of $\text{2.50 mol Fe(OH)"_2}$ is $\text{225 g}$.
The mass of one mole (molar mass) of $\text{Fe(OH)"_2}$ is $\text{89.85968 g/mol}$. http://pubchem.ncbi.nlm.nih.gov/compound/10129897$\sec t i o n = T o p T o \det e r \min e t h e m a s s o f$"2.50 mol Fe(OH)"_2"#, multiply the given moles by the molar mass.
$2.50 \cancel{\text{mol Fe(OH)"_2xx(89.85968"g Fe(OH)"_2)/(1cancel"mol Fe(OH)"_2)="225 g Fe(OH)"_2}}$