# How many moles are in 50 g of O?

Dec 18, 2015

There are 3 moles of O in 50 g.

#### Explanation:

To determine the number of moles in a given mass of an element, divide its given mass by its molar mass.

The mass of one mole (molar mass) of an element is its atomic weight (relative atomic mass) on the periodic table in g/mol.

The molar mass of oxygen is $\text{15.999 g/mol}$.

$50 \cancel{\text{g O"xx(1"mol O")/(15.999cancel"g O")="3 mol O}}$ (rounded to one significant figure)