A 1.46 mol sample of O2 gas is confined in a 35.4 liter container at 22.3 °C.

Question

A 1.46 mol sample of O₂ gas is confined in a 35.4 liter container at 22.3 °C.

If the volume of the gas sample is increased to 70.8 L, holding the temperature constant, the pressure will decrease. Which of the following kinetic theory ideas apply?

Choose all that apply.

With a larger volume to move in, the molecules hit the walls of the container less often.

With lower average speeds, on average the molecules hit the walls of the container with less force.

At higher volumes molecules have lower average speeds.

For a given gas at constant temperature, the force per collision is constant. Some other factor must cause the pressure decrease.

None of the Above

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Answer 1

Hi Alexandria,

For this question, it is important to remember that Volume and Pressure are inversely proportional to one another, this is determined by manipulating the ideal gas law. Because this question tells us that the temperature remains constant, we can be sure that a decrease in volume will have no effect on the average speed of the particles. Therefore, we can eliminate answers B. and C.

Because the temperature, and therefore speed of the particles remain the same, we know that the force per collision also remains constant. So, in this problem, pressure is only altered by the frequency of collisions. With an increase in volume, or space that the gas particles can move around in, the gas particles with collide at a lesser frequency and therefore, a decrease in pressure will occur.

This leads me to believe that both answers A. and D. are accurate responses.

I really hope this helps! Let me know if you have any further questions.