Final answer:
The density of methane gas at STP is 0.716 g/L. This is calculated by dividing the molar mass of methane (16.04 g/mol) by the standard molar volume (22.4 L/mol).
Step-by-step explanation:
The density of methane gas (CH4) at standard temperature and pressure (STP) can be found using the molar mass of methane and the standard molar volume.
STP is defined as 0°C (273 K) and 1 atm pressure.
The molar mass of methane is approximately 16.04 grams per mole (g/mol), and the standard molar volume is 22.4 liters per mole (L/mol) at STP.
To calculate density, we use the formula:
Density = Mass/Volume
At STP, one mole of methane gas will occupy 22.4 L. So the density can be calculated by dividing the molar mass by the molar volume:
Density of CH4 = 16.04 g/mol ÷ 22.4 L/mol
= 0.716 g/L
Comparing the densities of different gases at STP, we can see that the density of methane is less than that of ammonia, which has a density of 0.761 g/L at STP.
The sequence of densities for various hydrocarbons increases with the complexity of the molecule, as shown by ethane (C₂H₆) at 1.265 g/L, propane (C₃H₈) at 1.867 g/L, and so on.