# What molar quantity is represented by a 0.46*g mass of sodium metal?

Jul 15, 2017

Got a Periodic Table.......?

#### Explanation:

Of course you have, there is one in front of you now if you are doing your chemistry homwework.

$\text{Moles of element"="Mass of element"/"Molar mass of element}$

And so.........

$\text{Moles of sodium} = \frac{0.46 \cdot \cancel{g}}{22.99 \cdot \cancel{g} \cdot m o {l}^{-} 1} = 0.02000 \cdot m o l$.

Note that the quotient is dimensionally consistent......we wanted an answer in $m o l$, we got an answer in $\frac{1}{m o {l}^{-} 1} = \frac{1}{\frac{1}{m o l}} = m o l$ as required. Such a practice is known as $\text{dimensional analysis}$, and we use it to check our calculation. It is all too easy to divide instead of multiply or vice versa, and we have all done it.

You should post the answers for lithium and helium here.