# The mass of water is 18.00 grams per mole. What is the % of oxygen in water?

##### 1 Answer
May 26, 2018

"%O"_"by mass"=89%

#### Explanation:

We want the "mass of oxygen"/"mass of water"xx100%...and for a molar quantity of water this is...

(16.00*g*mol^-1)/(18.00*g*mol^-1)xx100%=88.9%..