Question

Which expression can be used to calculate the molar mass of an ideal gas? mRT + PV mRT ÷ PV PV ÷ mRT PV × mRT

Answer 1

Answer

mRT ÷ PV

Explanation

Ideal gas equation is

$\begin{gathered} PV=nRT \\ \\ Note,\text{ }n=\frac{m}{M};\text{ }where\text{ }m\text{ }is\text{ }the\text{ }mass\text{ }and\text{ }M\text{ }is\text{ }the\text{ }molar\text{ }mass \\ \\ So,PV=\frac{mRT}{M} \\ \\ Cross\text{ }multiply \\ \\ MPV=mRT \\ \\ Diveide\text{ }both\text{ }sides\text{ }by\text{ }PV \\ \\ \frac{MPV}{PV}=\frac{mRT}{PV} \\ \\ M=\frac{mRT}{PV} \\ \\ \Rightarrow M=mRT\div PV \end{gathered}$

Therefore, the expression which can be used to calculate the molar mass of an ideal gas is mRT ÷ PV