Final answer:
To calculate the density of H₂S at STP, the molar mass of H₂S is determined and then substituted into the ideal gas equation rearranged to solve for density, yielding a result of approximately 1.363 g/L.
Step-by-step explanation:
Calculating the Density of H₂S at STP
To calculate the density of hydrogen sulfide (H₂S) at standard temperature and pressure (STP), we use the ideal gas law PV = nRT, where:
- P is the pressure (1 atm at STP).
- V is the volume of the gas.
- n is the number of moles of the gas.
- R is the ideal gas constant (0.0821 L·atm/K·mol).
- T is the temperature (273 K at STP).
First, we calculate the molar mass of H₂S. To do so, we add the atomic mass of hydrogen (H) times 2 and the atomic mass of sulfur (S):
Molar mass of H₂S = (2 × 1.008 g/mol) + 32.065 g/mol = 34.081 g/mol
The density (ρ) of the gas can be expressed as ρ = m/V, where:
- m is the mass of the gas.
- V is the volume of the gas.
Using the ideal gas law, we can express the volume (V) in terms of n, R, and T because at STP P is a constant.
V = nRT/P
Thus, the density is:
ρ = m/(nRT/P)
Since m/n is the molar mass (M), we can rewrite the density as:
ρ = MP/RT
Substituting the known values:
ρ = (34.081 g/mol × 1 atm) / (0.0821 L·atm/K·mol × 273 K)
After calculating, the density of H₂S at STP is approximately:
ρ ≈ 1.363 g/L