Question

Nitrogen dioxide gas is dark brown in color and remains in equilibrium with dinitrogen tetroxide gas, which is colorless. 2NO2(g) ⇌N2O4(g) When the mixture was moved from room temperature to a higher temperature, the mixture turned darker brown. Which of the following conclusions about the mixture is true? The forward reaction is exothermic. The backward reaction has a negative net enthalpy. The colorless gas has a higher enthalpy than the brown gas. The equilibrium between the two forms of the gas is disturbed at high temperatures.

Answer 1

Answer:

The forward reaction is exothermic.

Explanation:

• Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

• When the mixture turned darker brown, this means that the reaction is shifted towards the left direction (reactants side).

• The temperature is increased and the reaction shifted to the reverse direction, this means that the forward direction is exothermic.

• Exothermic reaction releases heat and when increasing the temperature, the reaction will be shifted to the reverse direction to suppress the effect of increasing the temperature.
• So the right choice is: The forward reaction is exothermic.