# How many moles of molecules are in 35 g of octane, C_8H_18?

Apr 11, 2017

There are 0.307 moles of molecules in 35 g of octane.

#### Explanation:

You start by finding the molar mass of octane, ${C}_{8} {H}_{18}$

This is 114 grams, because there are eight moles of carbon atoms and eighteen moles of hydrogen atoms in each mole of octane molecules.

So, we total up 8 x 12 (for the carbon) and 18 x 1 (for the hydrogen).

Next, take the given mass, and divide by this molar mass:

$35 g \div 114 \frac{g}{\text{mol" = 0.307 "mol}}$

That's it! This answer is the number of moles of octane molecules contained in the 35 grams of the compound.