Final answer:
The molecular weight of the gas can be calculated using the Ideal Gas Law. After finding the number of moles from the given conditions, the molecular weight is determined to be approximately 89.16 g/mol.
Step-by-step explanation:
The student's question involves determining the molecular weight of a gas contained in a flask, using the conditions provided: a volume of 4.00 L, mass of 21.45 g, temperature of 400.0 K, and a pressure of 2.00 atm. This can be calculated using the Ideal Gas Law, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature.
First, we'll need to find the number of moles (n) using the Ideal Gas Law equation by rearranging it to n = PV/(RT), and then we can calculate the molecular weight (M) of the gas using the formula M = mass/n. Remember the units: pressure (P) in atmospheres (atm), volume (V) in liters (L), R is 0.0821 L·atm/(K·mol), and temperature (T) in kelvin (K).
Here's how the calculation would look:
n = (2.00 atm × 4.00 L) / (0.0821 Latm/K·mol × 400.0 K)
n=0.24mol
M = 21.45 g / 0.24 mol
M ≈ 89.16 g/mol