Determine the molar mass of a gas, which has a density of 4 kg / m ^ 3 at a temperature of 58 ° and a pressure of 0.25 MPa.

Data: Т (absolute temperature) = 58 ºС = 58 + 273 К = 331 К; P (pressure) = 0.25 MPa = 0.25 * 10 ^ 6 Pa; ρ (density) = 4 kg / m ^ 3.

Constants: R (universal gas constant) = 8.31 J / (mol * K)).

To determine the molar mass of a gas, we use the Mendeleev – Clapeyron equation:

P * V = (m / M) * R * T.

P = (m / V) * R * T / M = ρ * R * T / M.

M = ρ * R * T / P.

M = 4 * 8.31 * 331 / (0.25 * 10 ^ 6) = 0.044 kg / mol = 44 g / mol (carbon dioxide).

Answer: The molar mass of the gas is 44 g / mol.