(Easy 10 points) How much energy is transferred when 23.3 g of iron reacts to form Fe2O3

Heres the full question from a practice set:


3MgO(s) + 2Fe(s)Fe2O3(s) + 3Mg(s)
H°rxn = 980.9 kJ
How much energy is transferred when 23.3 g of iron reacts to form Fe2O3?

a. 409 kJ
b. 22,900 kJ
c. 643 kJ
d. 981 kJ
e. 205 kJ

I've been doing a practice set and understood them all except this and another. Which one is it for this? Please show work so I can understand. 10 points to best answer!

Hello,

You are given the mass of Fe used - 23.3 g . You also know the molar mass, which is 55.453 g/mol.

The H of reaction indicates that for every 2 moles of Fe used, 980.9 kJ is transferred.

So you set up the following conversion:

1 mol Fe 980.9 kJ
23.3 g Fe x ----------------- x ------------------- = 206 kJ which is approximately 205 kJ E
55.453 g Fe 2 mol Fe