What should a "theoretical background" to a chemistry lab include?

[Sybren]

I recently did a lab in my chemistry class which involved dissolving a 1982+ penny in nitric acid, then ammoniating it, and then using spetrophotometry to determine the percent copper (by mass) in a penny. At any rate, now the class has to write a "theoretical background" to the lab... the teacher described it as an abstract... why the lab works.

Anybody have any ideas as to exactly what information a theoretical background should include?

Thanks.