A gas mixture contains HBr, NO2, and C2H6 at STP. If a tiny hole is made in the container, which gas will effuse fastest? NO2 C2
H6 HBr They all effuse at the same rate. Which gas molecules have the highest average kinetic energy at this temperature? HBr NO2 C2H6 They all have the same average kinetic energy.
Let us first consider the molar Masses of each gas
HBr - 80.91 g/mol
NO2 - 46.0055 g/mol
C2H6 - 30.07 g/mol
We must remember that the greater the molar mass of a gas the lesser its velocity and average kinetic energy.
Looking at the gases listed, C2H6 have the highest average kinetic energy at this temperature since it has the lowest molecular mass. This reasoning is directly derived from Graham's law of diffusion in gases.
Hence C2H6 will effuse fastest when a hole is made in the container. It also possess the greatest average kinetic energy because it has the lowest molecular mass.
