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In this sweeping view, the 10 kilometer-wide crater Heimdall lies on the north polar plains of Mars. But the bright spot highlighted in the inset is the Phoenix lander parachuting toward the surface. The amazing picture was captured on May 25 2008 by the HiRISE camera onboard the Mars Reconnaissance Orbiter. Though the lander looks like it might be dropping straight into Heimdall, it is really descending about 20 kilometers in front of the crater, in the foreground of the scene. The orbiter was 760 kilometers away from Phoenix when picture was taken, at an altitude of 310 kilometers. APOD 5/30/2008
The State of Equilibrium
At equilibrium: rateAt equilibrium: ratefwdfwd = rate = raterevrev
ratefwd = kfwd[N2O4] raterev = krev[NO2]2
For the Nitrogen dioxide - dinitrogen tetroxide equilibrium:
N2O4 (g, colorless) = 2 NO2 (g, brown)
kfwd[N2O4] = krev[NO2]2 kfwd [NO2]2
krev [N2O4]= = Keq
1) Small k N2 (g) + O2 (g) 2 NO(g) K = 1 x 10 -30
2) Large k 2 CO(g) + O2 (g) 2 CO2 (g) K = 2.2 x 1022
3) Intermediate k 2 BrCl(g) Br2 (g) + Cl2 (g) K = 5
Initial and Equilibrium Concentrations for theN2O4-NO2 System at 100°C
Initial Equilibrium Ratio
[N2O4] [N2O4] [N2O4][NO2] [NO2] [NO2]2
0.1000 0.0000 0.0491 0.1018 0.211
0.0000 0.1000 0.0185 0.0627 0.212
0.0500 0.0500 0.0332 0.0837 0.211
0.0750 0.0250 0.0411 0.0930 0.210