Avogadro's Number Chemistry Example 2

Follow the full solution, then compare it with the other examples linked below.

Example 2

medium

How many individual oxygen atoms are in

1.5

mol of

\text{H}_2\text{O}

Solution

1
Each $\text{H}_2\text{O}$ molecule contains 1 oxygen atom.
2
Number of $\text{H}_2\text{O}$ molecules $= 1.5 \times 6.022 \times 10^{23} = 9.033 \times 10^{23}$ .
3
Number of O atoms $= 1 \times 9.033 \times 10^{23} = 9.03 \times 10^{23}$ .

Answer

9.03 \times 10^{23}\text{ oxygen atoms}

When counting atoms within molecules, multiply the number of molecules by the number of that type of atom per molecule. For H atoms in the same example, it would be