To calculate the mass of 1 dm^3 of air at STP (Standard Temperature and Pressure), we first need to determine the molar masses of oxygen and nitrogen.
- Oxygen (O2):
- Molar mass = 2 * atomic mass of oxygen
- Atomic mass of oxygen = 16 g/mol
- Molar mass of oxygen = 2 * 16 = 32 g/mol
- Nitrogen (N2):
- Molar mass = 2 * atomic mass of nitrogen
- Atomic mass of nitrogen = 14 g/mol
- Molar mass of nitrogen = 2 * 14 = 28 g/mol
Next, we find the mass of each gas present in 1 dm^3 of air at STP:
- Mass of oxygen in 1 dm^3 of air = (20/100) * 32 g
- Mass of nitrogen in 1 dm^3 of air = (80/100) * 28 g
Now, we can calculate the total mass of air:
Total mass = Mass of oxygen + Mass of nitrogen
Substituting the values:
Total mass = (0.20 * 32 g) + (0.80 * 28 g)
Total mass ≈ 6.4 g + 22.4 g
Total mass ≈ 28.8 g
Therefore, the mass of 1 dm^3 of air at STP is approximately 28.8 grams.
