PLEASE HELP! 30 POINTS! This energy diagram is for the thermal decomposition of solid mercury (II) oxide (also known as mercuric oxide) into liquid mercury and oxygen gas.

(a). Write a balanced equation for the reaction.
(b) Explain what feature is shown by the arrow labeled (a).
(c) Using chemical symbols and dashed lines (this can be done with type), draw what the activated complex or transition state might look like.
(d) Is this reaction exothermic or endothermic? Explain.

Since we are given that the mercury ion has a +2 charge, and we can assume that the oxygen ion has a -2 charge, both atoms have a 1:1 ratio.

Putting this into a decomposition reaction, we get:

[tex]\boxed{\rm 2PbO_{(s)} \to 2Pb_{(l)} + O_{2(g)}}[/tex]

b) The red arrow in the diagram shows the peak of the potential energy of the reactant-product system. This is also known as the activation energy of the reaction.

[tex]\boxed{\rm activation\ energy}[/tex]

c) In the transition state, the reaction has not gone to completion. Therefore, there will be a mixture of some solid and some liquid.

d) The reaction is endothermic because the potential energy of the products is greater than that of the reactants. (The "hill" ends higher than it starts.)