The thermite reaction is a very exothermic reaction; it has been used to produce liquid iron for welding. A mixture of 2 mol of powdered aluminum metal and 1 mol of iron(III) oxide yields liquid iron and solid aluminum oxide. How many grams of the mixture are needed to produce 313 kJ of heat?

Answer 1

2Al + Fe2O3 ==>2Fe and Al2O3 + ??kJ heat.
Do you know the kJ heat produced? If so,
313 kJ/?? kJ = moles Fe2O3 needed and convert that to grams Fe2O3.
(313 kJ/?? kJ) x 2 = moles Al needed and convert that to grams Al.
Add the grams Fe2O3 and grams Al to get the grams of the mixture needed.