A student collected a sample of a gas in a 220 mL gas bulb until is pressure reached 0.757 atm at a temperature of 25.0 . The sample weighed 0.299g. What is the molAR mass of the gas?

43.84 g/mol

Explanation:

We use the ideal gas law to find the number of moles of gas present.

So PV = nRT where P = pressure of gass = 0.757 atm, V = volume of gas = 220 mL = 0.22 L, T = temperature of gas = 25 °C = 273 + 25 = 298 K and R = molar gas constant = 0.082 L atm mol⁻¹K⁻¹.

So, n = PV/RT = 0.757 atm × 0.22 L/(0.082 L atm mol⁻¹K⁻¹ × 298 K) = 0.16654 L atm/24.436  L atm mol⁻¹ = 0.00682 mol.

Since mass of gas m = 0.299 g

and n = m/M where M = molar mass of gas

So, M = m/n

\= 0.299 g/0.00682 mol

= 43.84 g/mol

So, the molar mass of the gas is 43.84 g/mol

law of conservation of matter