# Question 85cd9

Feb 18, 2016

We will use just relation between molecular mass and molar mass for water.

#### Explanation:

First of all, let us consider the molecular mass of water:
- Each atom of hydrogen has a mass equal to 1 AMU (atomic mass unit).
- Each atom of oxygen has a mass equal to 16 AMU.
- Hence, a water molecule ($\text{H"_2 "O}$) has:

$2 \cdot 1 + 1 \cdot 16 = 18 \text{AMU}$

For any molecule (and also for every atom), its molecular mass in AMU equals to the mass of a mole in grams.
For example, for water: 1 molecule has a mass of 18 AMU, and this implies that 1 mole has a mass of 18 grams. Molecular mass in AMU equals to molar mass in grams. Always, atoms included.

Thus, the number of moles contained in 60 grams of water is:

{60 " grams"}/{18 " grams/mole"} = 3,33 " moles"#