What is the value of molar volume of a gas at $STP$?

Part one : Introduction to Standard temperature and pressure conditions$\left(STP\right)$

• The ideal or standard conditions considered as reference for other conditions are Standard temperature and pressure conditions$\left(STP\right)$).
• The Standard temperature and pressure conditions(STP) are $T=273.15KP=1atm$
• The gas constant will be equal to $R=0.0821\frac{atmL}{molK}$

Part two: Calculation of molar volume at Standard temperature and pressure conditions$\left(STP\right)$

• Consider ideal gas equation $PV=RT$
• The molar volume is calculated from $V=\frac{RT}{P}$
• We obtain molar volume to be

$$\begin{gathered} V=\frac{RT}{P} \\ V=\frac{0.0821{\displaystyle \frac{Latm}{molK}}\times 273.15K}{1atm} \\ V=0.0821\frac{L}{molK}\times 273.15K \\ V=22.4\frac{L}{mol} \end{gathered}$$

Therefore , the molar volume is equal to $22.4L/mol$ at Standard temperature and pressure conditions$\left(STP\right)$