The kinetic model of an ideal gas. Molecules hitting a wall make a pressure. The average kinetic energy of a molecule is set by the temperature alone. Gas molecules have an rms, an average and a most probable speed.
3 lessons, about 1 h 25 min3 simulations12 problems6 practice questionsPython in every lesson
Created by StemPy LabA gas presses on its walls because its molecules hit them all the time. The kinetic theory follows one molecule in a cube, adds up all the molecules, and gets . The same result in terms of energy is , where is the total translational kinetic energy.
Put the kinetic result next to the ideal gas equation . The total translational kinetic energy is , and the average kinetic energy of one molecule is . Temperature measures the average kinetic energy of the molecules. At one temperature it is the same for every gas.
The rms speed of gas molecules is . Light molecules move faster than heavy ones at the same temperature. The speeds spread out in the Maxwell distribution, with a most probable speed, an average speed and an rms speed in the ratio . The fast molecules explain why the Moon has no air.
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