Question

How many moles of water are
in 1.23x10¹8 water molecules?
[ ? ]×10[?]

Answer 1

2.04 x 10⁻⁶ moles H₂O

Step-by-step 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