so far, i’ve found the relative formula mass for:

Fe= 56

Fe2O3= 160

number of moles of Fe2O3= 700 000 000g / 160= 4 375 000

and thats where i got stuck.

(2) In the thermit reaction

2Al + Cr2O3 ==> 2Cr + Al2O3

Calculate the % yield when 180g of Chromium are obtained from 100g aluminium and 400g chromium (III) oxide.

i’ve already got that:

number of moles of Cr2O3= 400/ 152 = 2.632

and the number of moles of Cr = 180/52 = 3.462

but im not sure if this part is needed.

i know that the general formula for % yield is

(actual mass / calculated mass) x100

Can anyone help me finish these two questions off?

Thanks very much.