Question

question 2 points 2
which of the following statements is correct about calorimeter?
coffee - cup calorimeter is made of pvc cups and is a closed system
coffee - cup calorimeter is made of metal can and is a closed system
coffee - cup calorimeter is made of styrofoam cups and is an isolated system
coffee - cup calorimeter is made of plastic cups and is an isolated system

Explanation:

A coffee - cup calorimeter is typically made of styrofoam (which is a good insulator). An isolated system is one in which neither mass nor energy is exchanged with the surroundings. Styrofoam cups prevent heat transfer (energy exchange) to a large extent and also prevent mass exchange (as the reaction is carried out inside the cup with no mass escaping). PVC, metal, and plastic are not as good insulators as styrofoam for this purpose. Closed systems allow energy exchange but not mass exchange.

Answer:

Coffee - cup calorimeter is made of styrofoam cups and is an isolated system.