Question

How many total atoms are in 0.290 g of P2O5?

Answer 1

There are 8.61 × 10²⁰ atoms in 0.290 g P₂O₅.

Step 1. Convert grams of P₂O₅ to moles of P₂O₅.

$\text{Moles of P}_{2}\text{O}_{5} = \text{0.290 g } \text{P}_{2}\text{O}_{5} \times \frac{\text{1 mol }\text{P}_{2}\text{O}_{5}}{\text{141.94 g }\text{P}_{2}\text{O}_{5}} = \text{0.002 043 mol } \text{P}_{2}\text{O}_{5}$

Step 2. Convert moles of P₂O₅ to molecules of P₂O₅.

$\text{Molecules of } \text{P}_{2}\text{O}_{5} = \text{0.002 043 mol } \text{P}_{2}\text{O}_{5} \times \frac{6.022 \times 10^{23}\text{ molecules }\text{P}_{2}\text{O}_{5}}{\text{1 mol } \text{P}_{2}\text{O}_{5}}$

$= 1.23 \times10^{21}\text{ molecules } \text{P}_{2}\text{O}_{5}$

Step 3. Convert molecules of P₂O₅ to atoms.

There are seven atoms in 1 mol P₂O₅.

∴ $\text{Total atoms} = 1.23\times 10^{21 }\text{ molecules }\text{P}_{2}\text{O}_{5} \times\frac{\text{7 atoms}}{\text{1 molecule }\text{P}_{2}\text{O}_{5}} = 8.61 \times 10^{21}\text{ atoms}$