# What is the molar mass of water?

Jun 18, 2017

A water molecule contains $3$ $\text{atoms}$. These $3$ $\text{atoms}$ constitute $1$ $\text{water molecule}$.
A $\text{water molecule}$ contains $3$ $\text{atoms}$: $2 \times H$, and $1 \times O$. That is, those 3 atoms, when appropriately chemically bound, constitute a water molecule.
We know that $18.01 \cdot g$ of water contains ${N}_{A}$ water molecules, where ${N}_{A} = \text{Avogadro's number} = 6.022 \times {10}^{23} \cdot m o {l}^{-} 1$, and we get the mass by adding the atomic masses appropriately, i.e. $\left(2 \times 1.00794 + 15.999\right) \cdot g \cdot m o {l}^{-} 1$.
How many atoms in an $18 \cdot g$ mass of water?