Re: Re: How do you build a calorimeter?

Hi Johanna,

Funny thing, but your question reminded me of one of my early answers here at MadSci. To measure caloric content well, you have to be able to completely burn your sample (often by providing extra oxygen) as quickly as possible to avoid losing the heat produced. This needs to be done in a sealed chamber to contain the hot gases, and this chamber must be strong so that it does not explode.

Such calorimeters are often known as bomb calorimeters, and are not something you want to build yourself unless you know exactly what you are doing.

That having been said, you can build a simple classroom calorimeter to make rough measurements of caloric content. A simple Google search turned up several different classroom experiements, including this one (peanut burning), and this one (cashew burning, pdf format).

While each lab setup is different, the basic idea is to burn your sample in a confined volume, where it heats a carefully measured volume of water. You weigh the sample before and after, and the change in water temperature along with the weight change of your sample give you the caloric content in terms of energy per gram burned.

For your work I recommend reading a few of these labs together with your teacher to get a good idea of what works, and use these to plan your own setup. In particular, think about you should design the calorimeter so that it can burn both liquid samples (such as vegetable oil) and solid samples (such as wood). It's important that you use the same setup for all your different samples, so that you compensate for systematic errors.

Take a word of advice from an experimental scientist: safety first! Make sure you do everything under adult supervision, and be careful to take precautions against burning yourselves (or anything else besides the sample).

Good luck! This sounds like a fun project, and I hope it works out well for you.