Answer:
2.04 x 10⁻⁶ moles H₂O
Explanation:
To find the moles H₂O, you need to multiply the given value by Avogadro's Number. This number is a ratio between molecules and moles, thus granting you the way to convert between both units. It is important to arrange the ratio in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the sig figs of the given value (1.23 x 10¹⁸ molecules).
Avogadro's Number:
6.022 x 10²³ molecules = 1 mole
1.23 x 10¹⁸ molecules H₂O 1 mole
--------------------------------------- x ------------------------------------- =
6.022 x 10²³ molecules
= 2.04 x 10⁻⁶ moles H₂O
