Question #f678c
1 Answer
She is mixing up the concepts of chemical equilibrium with those of chemical kinetics.
Explanation:
Chemical equilibria respond to external changes by the position of equilibrium moving so as to nullify the change.
Take a reaction A + B = C, which is endothermic. It takes in ("involves") heat energy upon forming C.
Adding heat will cause the equilibrium to move further towards products (C) so that more heat is taken in, and the heat that has been added is "used up". On the other hand, reducing temperature will move the position of equilibrium towards reactants (A + B) in order to "use up" less heat energy.
However, that is position of chemical equlibria, and principle of Le Chatalier.
What the student is observing is not a change to the position of equilibrium, but a change to the rate of reaction . That is down to kinetics, and is due to the fact that increasing heat means that reactant molecules have more energy, therefore collide more frequently, and overall chemical reaction can occur faster.
So from this observation alone, you cannot conclude that the reaction is endothermic.
