Answer:
approximately 11.33g
Step-by-step explanation:
1. Molar mass of octane (C8H18): 114.22 g/mol
2. Molar mass of water (H2O): 18.02 g/mol
3. Moles of octane: 0.0699 moles (7.98 g / 114.22 g/mol)
4. Moles of water produced: 0.6291 moles (0.0699 moles of octane * 9)
5. Mass of water produced: 11.33 g (0.6291 moles * 18.02 g/mol)