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Where is the hydrogen? The average temperature of the atmosphere near the surface of the earth is about 20°C. (a) What is the root-mean-square speed of hydrogen molecules, H2, at this temperature? (b) The escape speed from the earth is about 11 km/s. Is the average H2 molecule moving fast enough to escape? (c) Compare the rms speeds of oxygen (O2) and nitrogen (N2) with that of H2. (d) So why has the hydrogen been able to escape the earth’s gravity, but the heavier gases (such as O2 and N2) have not, even though none of these gases has an rms speed equal to the escape speed of the earth? (Hint: Do all the molecules have the same rms speed or are some moving faster? Since the rms speed for H2 is greater than that of O2 and N2, which gas would have a higher percentage of ils molecules moving fast enough to escape?)
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