Question

how many atoms are in 54.9 grams of watert

Answer 1

how many atoms there are in 54.9 grams of water?

In order to calculate amount of atoms we need to know the amount of water (mol). To have it we can use next formula:

$$\nu = \frac {m (H _ {2} O)}{2 M (H) + M (O)};$$ $$\nu = \frac {5 4 . 9}{1 8} = 3. 0 5 m o l$$

For number of water atoms we have to use Avogadro constant $(\mathrm{N_A} = 6.02*10^{23}\mathrm{mol}^{-1})$

$$N = \nu * N _ {\mathrm {A}};$$ $$N = 3. 0 5 * 6. 0 2 * 1 0 ^ {2 3} = 1. 8 4 * 1 0 ^ {2 4}$$

There are $1.84 * 10^{24}$ atoms in $54.9\mathrm{g}$ of water