7. Gases

You have an evacuated container of fixed volume and known mass and introduce a known mass of a gas sample. Measuring the pressure at constant temperature over time, you are surprised to see it slowly dropping. You measure the mass of the gas-filled container and find that the mass is what it should be—gas plus container—and the mass does not change over time, so you do not have a leak. Suggest an explanation for your observations.

Suppose you have two 1-L flasks, one containing N2 at STP, the other containing CH4 at STP. How do these systems compare with respect to (c) average kinetic energy of the molecules?

Consider a 1.0-L sample of helium gas and a 1.0-L sample of argon gas, both at room temperature and atmospheric pressure. a. Do the atoms in the helium sample have the same average kinetic energy as the atoms in the argon sample?

A flask at room temperature contains exactly equal amounts (in moles) of nitrogen and xenon. c. The molecules of which gas have the greater average kinetic energy?

Calculate the kinetic energy of F2, Cl2, and Br2 at 298 K.

Calculate the root mean square velocity and kinetic energy of CO, CO2, and SO3 at 298 K. Which gas has the greatest velocity? The greatest kinetic energy? The greatest effusion rate?

At 25 °C (approximately room temperature) the rms velocity of an Ar atom in air is 1553 km>h. (b) What is the kinetic energy (in J) of an Ar atom moving at this speed?

Select the gas with the highest average kinetic energy per mole at 298 k.

Which gas molecules have the highest average kinetic energy at a given temperature?

Consider three gases all at 298 k: hcl, h2, and o2. list the gases in order of increasing average speed.