Final answer:
To find the molar mass of a gas given its mass, volume, pressure, and temperature, the Ideal Gas Law is used with unit conversions. The formula is then manipulated to solve for molar mass.
Step-by-step explanation:
The question asks for the determination of the molar mass of a gas, given its mass, volume, pressure, and temperature. To find the molar mass, we use the Ideal Gas Law equation PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature. By manipulating this equation, we can solve for the molar mass (M) using the formula M = (mRT)/(PV), where m is the mass of the gas in grams.
In the given problem, we have a mass (m) of 2.5 grams, volume (V) of 0.875 liters, pressure (P) of 685 torr (which needs to be converted to atmospheres), and temperature (T) of 35°C (which needs to be converted to Kelvin). Using the Ideal Gas Law and unit conversions, we can calculate the molar mass. Note that we must use the gas constant R = 0.0821 L·atm/(K·mol) for consistency in units.