How to calculate energy released

Question

Given the thermochemical equation for photosynthesis,

6H₂O(l) + 6CO₂(g) → C₆H₁₂O₆(s) + 6O₂(g)  ΔH = +3,091 kJ/mol

calculate the energy released from burning 32.1 g of C₆H₁₂O₆.

Answer 1

6H₂O(l) + 6CO₂(g) → C₆H₁₂O₆(s) + 6O₂(g)  ΔH = +3,091 kJ/mol

C₆H₁₂O₆(s) + 6O₂(g) → 6H₂O(l) + 6CO₂(g) ΔH = -3,091 kJ/mol (reverse equation and a negative ∆H)

This equation tells us the ONE MOLE C6H12O6 liberates 3091 kJ of energy

molar mass C6H12O6 = 180 g / mole

32.1 g x 1 mol / 180 g = 0.178 mols C6H12O6

0.178 mols x 3091 kJ / mol = 551 kJ of energy released (should have a - sign, but since said it is being released, no real need for the - sign)