Answer: Your welcome!
Step-by-step explanation:
(a) The amount of oxygen gas required to react with 7.98 liters of hydrogen gas at STP in the synthesis of water is 7.98 liters. This is because the balanced chemical equation for the synthesis of water is 2H2 + O2 → 2H2O. Since the moles of hydrogen gas are equal to the moles of oxygen gas, the volume of oxygen gas required would be equal to the volume of hydrogen gas.
(b) The mass of water produced by the reaction is equal to the mass of hydrogen gas (2 x 1.00794 g/mol) plus the mass of oxygen gas (16.00 g/mol) multiplied by the molar ratio of hydrogen gas to oxygen gas (2:1). This gives us a total mass of 18.01588 g.