Question

How many total atoms are in 0.250g of P2O5?

Answer 1

Explanation:

According to the mole concept, there are $6.022 \times 10^{22}$ atoms present.

It is given that mass is 0.250 g. And, number of moles are equal to mass divided by molar mass.

Mathematically,       No. of moles = $\frac{mass}{\text{molar mass}}$

As molar mass of $P_{2}O_{5}$ is 283.88 g/mol. Therefore, putting given values into the above formula as follows.

                 No. of moles = $\frac{mass}{\text{molar mass}}$

                                       = $\frac{0.250 g}{283.88 g/mol}$

                                       = 0.0008 mol

Hence, number of atoms present in 0.0008 mol are as follows.

                      $0.0008 mol \times 6.022 \times 10^{22} atoms/mol$

                     = 0.0048 atoms

Thus, we can conclude that there are 0.0048 atoms in 0.250 g of $P_{2}O_{5}$.

Answer 2

1. Calculate no. of moles by dividing  mass given/molar mass 
= 0.250 /283.8 
2. Now multiply no. of moles with avogadro's no.
3. The answer indicates no. of total atoms..