# Question 2b53f

##### 1 Answer
Oct 8, 2017

6 moles of Oxygen

#### Explanation:

In the molecular formula, how many moles of oxygen are there? You can find the answer by multiplying $3$ by $2$, so there are 6 moles of oxygen. You can do this since there is one mole of $C u {\left(N {O}_{3}\right)}_{2}$. If there were $2$ moles of $C u {\left(N {O}_{3}\right)}_{2}$ instead, you would have an answer of 12 moles, since there would be twice as many $C u {\left(N {O}_{3}\right)}_{2}$ molecules now.

As an aside, how many moles of Copper (Cu) are there? There's $1$, since Cu doesn't have a subscript.

If you're uncertain why this is the case, you can always use the mass percent concept to double check:

((16.00 " g Oxygen")(6 " moles Oxygen"))/(187.56 " grams "Cu(NO_3)_2) * 100 = 51.18 %

Now we can find the number of moles of oxygen in one mole of $C u {\left(N {O}_{3}\right)}_{2}$:

(0.5118 * 187.56 " grams " Cu(NO_3)_2) * (1 " mole Oxygen")/(16.00 " grams of Oxygen") = 6 " moles of Oxygen"#