The following thermochemical equation is for the reaction of iron(s) with chlorine(g) to form iron(III) chloride.How many grams of Fe(s) would have to react to produce 99.5 kJ of energy?

Question

1. 2Fe(s) + 3Cl₂(g)2FeCl₃(s)    H = -799 kJ

Answer 1

So, the equation tells us the 799 kJ of heat energy are released when TWO moles of Fe(s) react. From this information we can then figure out how many moles of Fe(s), and hence how many grams of Fe(s) will be required to generate 99.5 kJ of heat energy. Remember, this is based on MOLES, not grams, so we must find moles first.

99.5 kJ x 2 moles Fe / 799 kJ = 0.249 moles Fe needed to generate 99.5 kJ of heat

Convert this to grams:

0.249 mols Fe x 55.8 g Fe / mol Fe = ANSWER in grams