The molecular weight of a substance is calculated by adding the molecular mass of each element present in the molecule multiplied by the number of times each element is in the molecule. For greater clarity, we can organize a table that allows us to do the calculations. We have the following structure for water:
The molecular weight of water will be:
2.01568 + 15.999 = 18.0468=18.0 g/mol
Answer= 18.0