Question

Fe2O3 + H2 --> Fe + H2O

A) what mass of hydrogen gas must be consumed to produe 10.0 g of iron metal?

B) what mass of iron(lll) oxide, Fe2O3, must be consumed to prepare 2.50g of iron metal

Answer 1

A) 10.0g of Iron is
`(10.0)/(55.8)=179mmol` of Iron.

One mole of dihydrogen is required to form one mole of iron, hence you'll need
`0.179*1.00=0.179g` of dihydrogen.

B) Likewise : 2.50g of Iron is
`(2.50)/(55.8)=44.8mmol` of Iron, hence we'll need
`44.8*(3*16+2*55.8)=7.15g` of Fe2O3.