Final answer:
Lowering the temperature of the equilibrium system 2NO2(g) → N2O4(g) will cause the reaction to favor the reverse process, resulting in the formation of more N2O4 gas, which is colorless, and a decrease in the brown colored NO2 gas.
Step-by-step explanation:
When the temperature of the system containing the equilibrium 2NO2(g) → N2O4(g) + 55.3 KJ is lowered, the reaction will favor the endothermic reverse process, where dinitrogen tetroxide (N2O4), which is colorless, is formed from nitrogen dioxide (NO2), which is dark brown in color. This is in accordance with Le Chatelier's Principle, which states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change. In this case, by lowering the temperature, the system shifts to produce more N2O4 to absorb the heat that was removed, thus resulting in a decrease in the concentration of NO2, causing the brown color to fade.
Lowering the temperature of the equilibrium system 2NO2(g) → N2O4(g) will cause the reaction to favor the reverse process, resulting in the formation of more N2O4 gas, which is colorless, and a decrease in the brown colored NO2 gas.