The molar mass of a gas with a density of 1.25 g/L at STP is calculated using the molar volume of 22.4 L/mole leading to a molar mass of 28.0 g/mol.
The molar mass of a gas with a density of 1.25 g/L at STP is 28.0 g/mol.
At Standard Temperature and Pressure (STP), the molar volume of an ideal gas is 22.4 L/mole. This means that one mole of any ideal gas will occupy 22.4 liters at STP. The density (p) of a gas is related to its molar mass (MM) and molar volume (Vm) by the formula p = MM/Vm. Given the density of the gas is 1.25 g/L, and using the molar volume of 22.4 L/mole at STP, we calculate the molar mass by rearranging the formula to MM = p × Vm, yielding a molar mass of 1.25 g/L × 22.4 L/mole = 28.0 g/mol.
The knowledge of gas density at STP allows us to directly calculate the molar mass of the gas using the molar volume of 22.4 L/mole as a conversion factor.