Physical Science – Multiple Choice When plotting the energy of the components of a
slow reaction, such as the conversion of diamond into graphite, versus the reaction progress,
which of the following best represents the shape of the curve?
W) Linearly upward
X) Linearly downward
Y) A trough in the middle
Z) A peak in the middle
ANSWER: Z) A PEAK IN THE MIDDLE

During conversion or chemical changes, first step is bond breaking ( endothermic ie. heat is needed) and then new bond formation (exothermic means energy released ). So in the energy profile first energy increases reaches a maxima and then energy decreases.