Slides Shown Friday Nov. 7, 2008

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 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

Nitrogen dioxide shown immediately after expanding

Reaction of 2NO 2 (g) and N 2 O 4 (g) over time in a closed vessel

Reddish brown nitrogen dioxide, NO 2 (g)

Reaching Equilibrium on the Macroscopic and Molecular Level N 2 O 4 (g) 2 NO 2 (g) Colorless Brown

The State of Equilibrium At equilibrium: rate fwd = rate rev rate fwd = k fwd [N 2 O 4 ] rate rev = k rev [NO 2 ] 2 For the Nitrogen dioxide - dinitrogen tetroxide equilibrium: N 2 O 4 (g, colorless) = 2 NO 2 (g, brown) k fwd [N 2 O 4 ] = k rev [NO 2 ] 2 k fwd [NO 2 ] 2 k rev [N 2 O 4 ] = = K eq 1) Small kN 2 (g) + O 2 (g) 2 NO (g) K = 1 x ) Large k 2 CO (g) + O 2 (g) 2 CO 2 (g) K = 2.2 x ) Intermediate k 2 BrCl (g) Br 2 (g) + Cl 2 (g) K = 5

Reaction Direction and the Relative Sizes of Q and K

Initial and Equilibrium Concentrations for the N 2 O 4 -NO 2 System at 100°C Initial Equilibrium Ratio [N 2 O 4 ] [NO 2 ] [NO 2 ]

Changes in concentration with time for the reaction H 2 O (g) + CO (g) H 2 (g) + CO 2 (g)

H 2 O and CO are mixed in equal numbers H 2 O (g) + CO (g) H 2 (g) + CO 2 (g)

Changes with time in the rates of forward and reverse reactions H 2 O (g) + CO (g) = H 2 (g) + CO 2 (g)

Concentration profile for the reaction N 2 + 3H 2 = 2NH 3