Step-by-step explanation:
Calorimeters are utilized to measure heat transfers or flow.
Calorimeters are made of insulating substances.
To be a perfect calorimeter it should be sealed, with no heat flow and insulated properly this permits the precise measurement of the heat involved during the chemical reaction.
A Styrofoam coffee cup is an imperfect calorimeter because there are several means by which heat is released during a chemical reaction and leave the Styrofoam