Hello!
We know that by the Law of Avogrado, for each mole of substance we have 6.02 * 10²³ atoms, if:
The molar mass of water (H2O)
H = 2 * (1u) = 2u
O = 1 * (16u) = 16u
---------------------------
The molar mass of H2O = 2 + 16 = 18 g / mol
If:
1 mol we have 6.02 * 10²³ atoms
1 mole of H2O we have 18 g
Then we have:
18 g ------------- 6.02 * 10²³ atoms
5 g -------------- x
[tex] \dfrac{18}{5} = \dfrac{6.02*10^{23}}{x} [/tex]
[tex] 18*x = 5*6.02*10^{23} [/tex]
[tex] 18\:x = 3.01*10^{24} [/tex]
[tex] x = \dfrac{3.01*10^{24}}{18} [/tex]
[tex] \boxed{\boxed{x \approx 1.672*10^{23}\:atoms}}\end{array}}\qquad\checkmark [/tex]
I Hope this helps, greetings ... DexteR! =)
