The molar mass of the gas can be calculated using the ideal gas law:
PV = nRT
where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
Rearranging the equation to solve for n, we get:
n = PV/RT
Substituting the given values, we get:
n = (1.44 atm)(0.570 L)/(0.0821 L·atm/mol·K)(281 K)
n = 0.0251 mol
The mass of the gas is 0.993 g, so the molar mass can be calculated as:
Molar mass = Mass / Number of moles
Molar mass = 0.993 g / 0.0251 mol
Molar mass = 39.6 g/mol
Therefore, the molar mass of the gas is approximately 39.6 g/mol.