What is the quality of the water? The relative molecular weight of water?

1) What is the quality of the water? 2) The relative molecular weight of water? 3) Molar mass? 4) Mass fraction of oxygen? 5) Mass fraction of hydrogen?

1) A water molecule consists of two chemical elements: hydrogen and oxygen. Number of atoms – 3: 2 hydrogen atoms and 1 oxygen atom;
2) The relative molecular weight is calculated using the periodic system of D.I.Mendeleev:
Mr (H2O) = Ar (H) * N (H) + Ar (O) * N (O) = 1 * 2 + 16 * 1 = 18;
3) The molar mass is numerically equal to the relative molecular mass:
M (H2O) = Mr (H2O) = 18 g / mol;
4) ω (O in H2O) = N (O in H2O) * Ar (O) * 100% / Mr (H2O) = 1 * 16 * 100% / 18 = 88.89%;
5) ω (H in H2O) = 100% – ω (O in H2O = 100% – 88.89% = 11.11%.