Final answer:
The mass of 1.27 mol of water is calculated using the molar mass of water (18 g/mol), resulting in 22.886 g, which rounds to option A, 22.5 g.
Step-by-step explanation:
The question asks to calculate the mass of 1.27 mol of water. To find this, we use the molar mass of water. The molar mass of water (H2O) is the sum of the mass of 2 hydrogen atoms and 1 oxygen atom. Hydrogen has a mass of approximately 1 g/mol, and oxygen has a mass of approximately 16 g/mol, therefore one mole of water molecules will have a mass of 18 g (16 g for oxygen + 1 g for each hydrogen atom).
Using the molar mass as a conversion factor:
Mass = number of moles × molar mass
Mass = 1.27 mol × 18.02 g/mol
Mass = 22.886 g
The closest answer to this calculated mass is option A, 22.5 g, which is typically how you would report it since most mass measurements in a classroom setting are reported to one decimal place or the nearest whole number.