Question

How many moles are in $50\mathrm{grams}$ of oxygen?

Answer 1

The number of moles is calculated by :

• To calculate several moles, Moles $=$ Mass of the element($\mathrm{g}$) $/$Molar mass(${\mathrm{gmol}}^{-1}$).
• To calculate the number of moles, the molar mass of the substance should be known

Step 1: To find several moles present in $50\mathrm{g}$ Oxygen.

Step2: Given- The molar mass of oxygen is$16\mathrm{g}/\mathrm{mol}$.

Step 3: Calculation: $$\begin{gathered} \mathrm{Moles}=\mathrm{Mass}\mathrm{of}\mathrm{the}\mathrm{element}\left(\mathrm{g}\right)/\mathrm{Molar}\mathrm{mass}\left({\mathrm{gmol}}^{-1}\right) \\ \mathrm{Number}\mathrm{of}\mathrm{moles}=50/16=3.125\mathrm{mol} \end{gathered}$$

So, the number of moles will be $3.125$ moles.

Hence, by knowing the mass of the element and molar mass, several moles can be calculated.