Final answer:
For 3.500 moles of water to fully react according to the equation, they must absorb 1,634.25 kJ. This number is obtained by calculating the heat absorbed per mole of water and then multiplying it by 3.500 moles.
Step-by-step explanation:
If 3.500 moles of water react completely according to the provided equation (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ ΔH = 2,803 kJ), we need to find out how much heat must be absorbed, measured in kilojoules. Firstly, we observe that in the reaction equation, 6 moles of water are involved to release 2,803 kJ of heat. Since this is a photosynthesis reaction where water is a reactant, the heat absorbed would be the opposite of the heat released.
So, if one mole of water absorbs -2,803 kJ / 6, then 3.500 moles will absorb:
(-2,803 kJ/6) × 3.500 moles = -1,634.25 kJ
Therefore, the amount of heat absorbed will be positive, so we drop the negative sign to get 1,634.25 kJ as the amount of heat that must be absorbed by 3.500 moles of water. Looking at the answer choices, none exactly matches this result, implying there might be an error in the question or answer choices.