# What result do you get when you multiply the number of moles of a sample by the following conversion factor? (g of element)/(1 element)

Dec 1, 2016

I think you mean to multiply the mass of an element by $\frac{1}{\text{molar mass of the element}}$

#### Explanation:

And if we do this we get:

"mass of the element (g)"/("molar mass of the element"(g*mol^-1)), we get an answer in $\text{moles}$, because, $\frac{g}{g \cdot m o {l}^{-} 1} = \frac{\cancel{g}}{\cancel{g} \cdot m o {l}^{-} 1} = \frac{1}{\frac{1}{m o {l}^{-} 1}} = m o l$ as required.

So if I have $12 \cdot g$ of carbon, I have a molar quantity of $\frac{12 \cdot \cancel{g}}{12.011 \cdot \cancel{g} \cdot m o {l}^{-} 1} \cong 1 \cdot m o l$.

The quotient gives an answer in $\text{moles}$ dimensionally.

From where do I get the molar masses? Have I memorized them? Do you have to memorize them for an exam?

Actually, you will memorize the more common molar masses, i.e. those of oxygen, nitrogen, carbon, sodium, iron...........