About the box we created:

Requirements: 

Poor heat conductor, little air in container, light and polished surface (not dull)

 

The box we created is made of styrofoam and it is wrapped with aluminum. I

nside the styrofoam box is another layer of styrofoam.

The second layer of styrofoam that is sealed with tape creates an artificial vacuum. Dead air is a very good insulator of heat because its molecules have a lot of spaces between them. The large amount of spaces between the molecules does not facilitate the conduction of heat which requires molecules to be relatively close to each other so that when one molecule gains enough heat and kinetic energy to vibrate, this heat energy can then be transferred to another molecule. In addition, styrofoam is a poor conductor of heat so the process of conduction is also further restricted. Therefore, these will reduce the heat gain of the container holding the ice kacang by reducing the conduction of heat in the container.

Secondly, Styrofoam can trap air in its foam pockets. This prevents some air from moving about freely throughout the container. Since there is more still air (the one trapped in the pockets) than freely moving air, convection of the air (bulk movement of the air due to changes in density) is not very efficient. This makes Styrofoam a good insulator of heat. Since convection cannot occur as well in a Styrofoam container than in a plastic container, we selected Styrofoam so that it can reduce the heat gained inside the container by convection.

Styrofoam is used because it is white in colour and is able to reflect heat more effectively. This albedo effect allows the container to reflect some of the incoming heat from its surroundings, preventing a large amount of heat from penetrating into the container. Black surfaces absorb a lot of heat, therefore we chose to use a white surface which will absorb lesser heat so the container holding the ice kacang would not gain too much heat. Furthermore, we wrapped aluminum around the Styrofoam. Aluminum has a shiny surface. Unlike dull surfaces, the shiny surface of aluminum reflects heat better. In fact, dull surfaces radiate heat much more than shiny surfaces. These prevent the ice kacang from melting easily due to radiation.