Question

One molecule of water $\left(H_{2}O\right)$ contains two atoms of hydrogen and one atom of oxygen. A hydrogen atom has a mass of $1.0u$ and an atom of oxygen has a mass of $16u$, approximately.
What is the mass in kilograms of one molecule of water?

Answer 1

As we know,

In atomic mass units, the mass of one molecule is $(16+1+1)u=18u$. Using Eq $1-9$ we find

$18u=\left(18u\right)\left(\frac{1.6605402\times {10}^{-27}kg}{lu}\right)=3.0\times {10}^{-26}kg$