Considering the STP conditions and the definition of molar mass, the molar mass of the gasis equal to 30.016 g/mole.
The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0°C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.
Molar mass is the amount of mass that a substance contains in one mole.
The density of a substance is the mass you have per unit of volume of that substance. So you know that 1.43 g/L means that 1 L of this gas has a mass of 1.43 g.
Knowing that one mole of gas at STP occupies 22.4 litres, you can say that 1 mole of this gas will have a mass of:
22.4 L× [tex]\frac{1.34 g}{1 L} [/tex]= 30.016 g
Finally, if 1 mole of this gas has a mass of 30.016 g, its molar mass is equal to 30.016 g/mole.
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