Question

*I think it’s either the first one or the last one, but I’m just not sure.

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 light brown color equilibrium mixture was moved from room temperature to a lower temperature, the mixture turned lighter brown in color. Which of the following conclusions about this equilibrium mixture is true?

This reaction is endothermic because the system shifted to the left on cooling.

This reaction is endothermic because the system shifted to the right on cooling.

This reaction is exothermic because the system shifted to the left on cooling.

This reaction is exothermic because the system shifted to the right on cooling.

Answer 1

Answer:

This reaction is exothermic because the system shifted to the right on cooling.  

Step-by-step explanation:

 2NO₂   ⇌   N₂O₄

brown    colourless

According to Le Châtelier's Principle, when a stress is applied to a system at equilibrium, the system will respond in a way that tends to relieve the stress.

You applied a stress by cooling the system (removing heat). The system responded by moving in a direction that created more heat.

The mixture became lighter brown on cooling, so the position of equilibrium must have shifted to the right to generate the heat.

The reaction is exothermic.

Answer 2

When the light brown color equilibrium mixture was moved from room temperature to a lower temperature, the mixture turned lighter brown in color shows this reaction is exothermic because the system shifted to the right on cooling.

What is equilibrium law?

According the the equilibrium law, if any external element is added in the equilibrium state, ten the whole reaction will shifts to that side which reduces the effect of that additional element.

Given chemical reaction is:

2NO₂(g) ⇌ N₂O₄(g)

Where NO₂ shows brown color and N₂O₄ is colorless gas. If we notice a light brown color of the mixture when we moved from room temperature to a lower temperature then the reaction will shifts to the right side and will show exothermic behavior to overcome the external effect.

Hence, option (d) is correct.

To know more about equilibrium law, visit the below link:

https://brainly.com/question/2943338