Answer:
Explanation:
Remark
First of all you have to identify what is happening. You make the following observations.
The solution in the test tube in a cold water bath is colorless.
As you add heat, the color changes from colorless to brown.
What you are told
N2O4 is colorless
NO2 is brownish red.
What you conclude
The reaction is endothermic. That means it requires heat to happen. An endothermic reaction is
A + Heat ===> B
So you have three possible correct answers
N2O4 + 14 kCal ===> 2NO2
N2O4 ====> 2NO2 dH = 14 kCal
N2O4 ====> 2NO2 - 14 kCal
I can't read the last 4 equations.
Other answers
As the temperature increased, the N2O4 became less.
As the temperature increased, the products were favored. (color change)
The reaction is exothermic (gives off heat) when the reaction goes from
NO2 - Heat ===> N2O2
