Final answer:
The density of a 0.300 g sample of argon gas at STP is approximately 0.6895 g/L.
Step-by-step explanation:
The density of a gas is calculated using the formula density = mass / volume. To find the density of argon gas at STP (standard temperature and pressure), we need to know the molar mass of argon. The molar mass of argon is 39.948 g/mol. Since we have a 0.300 g sample of argon gas, we can use the formula density = mass / volume to find the volume.
density = mass / volume
volume = mass / density
volume = 0.300 g / (39.948 g/mol * 22.4 L/mol)
volume = 0.300 g / 0.6895 g/L
volume ≈ 0.435 L
Therefore, the density of a 0.300 g sample of argon gas at STP is approximately 0.6895 g/L.