Answer:
To calculate the molar mass of the gas, we can use the ideal gas law, which relates the pressure, volume, temperature, and number of moles of a gas:
PV = nRT
where P is the pressure in atmospheres, V is the volume in liters, n is the number of moles, R is the ideal gas constant (0.0821 L·atm/mol·K), and T is the temperature in kelvin.
First, we need to convert the temperature to kelvin:
T = 99.0 °C + 273.15 = 372.15 K
Next, we can calculate the number of moles of gas using the ideal gas law:
n = PV/RT
where P is the pressure in atmospheres (we convert 748 torr to atmospheres by dividing by 760 torr/atm), V is the volume in liters (we convert 250 mL to 0.25 L), R is the ideal gas constant, and T is the temperature in kelvin:
n = (748/760) × 0.25 L / (0.0821 L·atm/mol·K × 372.15 K) = 0.0105 mol
Finally, we can calculate the molar mass of the gas by dividing the mass of the condensed vapor (1.097 g) by the number of moles:
molar mass = mass/number of moles = 1.097 g / 0.0105 mol = 104.38 g/mol
Therefore, the molar mass of the gas is approximately 104.38 g/mol.
Step-by-step explanation: