How many atoms of hydrogen are there in 18 g of water?

Feb 19, 2018

$\approx 1.2 \cdot {10}^{24}$ atoms of hydrogen

Explanation:

Water has a molar mass of $18.01528 \setminus \text{g/mol" ~~ 18 \ "g/mol}$.

So, in $18 \setminus \text{g}$ of water, there will be

(18cancel"g")/(18cancel"g""/mol")=1 \ "mol"

Since water has a chemical formula of ${H}_{2} O$, there will be $2$ moles of hydrogen in every mole of water.

In one mole of water, there will exist approximately $6.02 \cdot {10}^{23}$ water molecules.

So, there will be a total of $6.02 \cdot {10}^{23} \cdot 2 \approx 1.2 \cdot {10}^{24}$ hydrogen atoms.