Determination of molar mass

Exercise 1

A gaseous substance is introduced into a flask previously emptied of air with volume $1.12\;L$ and mass $45.31\;g$. After introduction it is noted that the flask containing the gas under normal conditions of temperature and pressure has a mass of $48.41\. g$. Calculate the molar mass of the introduced gas.

Number of moles = $n$ $=$ $\frac{V}{22.4}$ = $\frac{1.12}{22.4} $ $n$ $=$ $\frac{m}{M}$ $M$ = $\frac{m}{n}$ = $\frac{(48.41-45.31)\cdot 22.4}{1.12}$ = $62.0\frac{g}{mol}$