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Kinetic molecular theory Consider two 1-L samples of gas: one is H2 and the othe

ID: 560723 • Letter: K

Question

Kinetic molecular theory Consider two 1-L samples of gas: one is H2 and the other is O2. Both are at 1 atm and 25 °C. (1) Which sample has the greater mass? (2) Which sample has the greater density? (3) Which sample has the greater average kinetic energy? (4) Which sample has the greater average molecular speed? Atmosphere of Mars On the surface of Mars, the average temperature is -50 °C and the atmospheric pressure is only 600. Pa (pascals), which is less than 1% of that of Earth. The Martian atmosphere consists of 96% carbon dioxide, 2.1% argon, and 1.9% dinitrogen gas by volume. (Report numerical answers below in non-scientific notation, to the correct number of significant figures. Caution: Some students still have trouble with significant figures at this stage.) (1) The mole fraction of argon gas is (2) The partial pressure of argon gas is (3) The figure below shows distributions of particle speeds for the argon and dinitrogen gases in the Martian atmosphere, which curve corresponds to argon Pa. Molecular speed

Explanation / Answer

Q1

if same amount of moles, then

molar mass of H2 < molar mass of O2

therefore, total mass of O2 > mass of H2

Q2

density --> depends on mass / volume

since V = 1 L for both

the Density of O2 > Density of H2

Q3

avg. kientic energy --> depends on Tempearture

If same T, then both have the SAME kinetic energy ( in average)

Q4

faster mlecular speed --> depends on Tempearture and Mass

if Mass is low, then V is high, therefore H2 Velocity > O2 velocity