# How many moles are in 15.5 g #SiO_2#?

##### 1 Answer

Feb 20, 2016

About a 1/4 of a mole.

#### Explanation:

Silicon dioxide has a molar mass of

So to find the molar quantity of silicon dioxide, all I have to do is divide the mass by the molar mass:

By doing the equation with units included it helps to prevent me from making mistakes. Should I divide or should I multiply? The fact that the calculation gave me an answer in moles persuades me that I did the right thing. It's all too easy to make a mistake.

What is silicon dioxide? How do you calculate its molar mass?