Question

Consider the reaction
2 Al2O3(s) -> 4 Al(s) + 3 O2(g) .

H = +3339.6 kJ/mol
What is the change in heat when 0.455 L of a 3.60 M Al solution reacts with excess O2 ?
1. -685 kJ
2. -21,962 kJ
3. -1368 kJ
4. -2738 kJ
5. -5477 kJ
6. -26,521 kJ
7. -424 kJ
8. -1695 kJ

Answer 1

Molarity = moles/Liters so moles = Molarity * Liters

moles = 3.60 M * .455 L = 1.64 moles of Al

1.64 moles Al / 4 moles Al = .4095 (this number is how many times the reaction can be done) .4095 moles * -3339.6 kj/mol (negative because you're doing reverse reaction and reverse reaction is reversed heat) = -1368 kj

answer = -1368 kj

Answer 2

-2738