Science Buddies: "Ask an Expert"

We are struggling to use an electric calorimeter to measure calories of foods. It came with no instructions. Could someone help? We got the idea for the science fair experiment from Science Buddies. We need help ASAP.

THANKS

Hi Djhockett,

Can you post some identifying information on the calorimeter you are attempting to use? And can you provide some details on how you have attempted to use the calorimeter?

I will attempt to provide some guidance but have limited options through this medium.

AeroSE

This is the type of electric calorimeter. We placed water and dry cat food in the center reservoir. Connected the battery and measured temperature change of the water. The food broke apart in the water. We do not beleive this is an accurate way to measure calories. Another science teacher suggested that the water level should be below the electrodes and to hang a food sample on the electrodes. In this method he expected the food to burn and that we could measure the temperature change of the water.

Here is a picture of the calorimeter.

https://www.flinnsci.com/globalassets/f ... 324c024369

Hi,

It does sound reasonable that the water level would be below the electrodes if there is only 1 distinct area within the calorimeter (i.e. no reservoir within a larger container), as the idea is to burn the food and measure the energy released by the breaking of the chemical bonds in the food. In that case, you could then measure the temperature change of the water. This would be odd though because, if the water is below the burning food, the heat lost by the food would be mostly transferred to the air. However, I'm not sure exactly how the center reservoir of your calorimeter is oriented with respect to the electrodes -- could you possibly send a picture of the inside of the calorimeter? Thank you! If there is a center reservoir and then a container surrounding it, then I suspect the water is supposed to go in the outer container and the food in the center reservoir. The electrodes are then connected to the food and the food will burn, causing a release of heat that will be transferred to the water in the external area, causing a temperature change. I hope this helps!

Elena

Hello!

Here is another approach to food calorimetry if you would like to try it out. Essentially, you would be burning a mass of food (such as cat food or a potato chip) underneath a can of water. You would have measure its initial and final temperature to get the change of temperature of the water. Here is the link to how you can set up this experiment:
https://www.carolina.com/teacher-resour ... tr23949.tr

Hope this helps!