What is the density of a mixture of 40% oxygen and 60% helium at STPD?

Question

Quizplus · Accepted Answer

The molecular weight of oxygen is 32 g/mol and that of helium is 4 g/mol. Therefore, the average molecular weight of the mixture can be calculated as:
(0.4 x 32) + (0.6 x 4) = 12.8 + 2.4 = 15.2 g/mol
At STPD, the density of a gas can be calculated using the ideal gas law:
PV = nRT
where P = pressure, V = volume, n = number of moles, R = universal gas constant, and T = temperature.
At STPD, the pressure is 1 atm and the temperature is 273.15 K. Rearranging the ideal gas law equation to solve for density, we get:
density = (n x MW) / V = (P x MW) / (RT)
Plugging in the values, we get:
density = (1 x 15.2) / (0.0821 x 273.15) = 0.674 g/L
Therefore, the answer is C, 0.68 g/L (rounded to two decimal places).

What Is the Density of a Mixture of 40% Oxygen