Question

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

Answer 1

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