 In this video, we are going to learn about calorimeters, what they are, how they might be used, and why they are used. A calorimeter is a device used for calorimetry. The process of measuring the change in heat of chemical reactions, or physical changes, as well as heat capacity for a material. When you look at food items, their energy content was worked out by burning the food in oxygen to see how much energy is released. This corresponds to the energy content label and is given in calories. To do this, you have to use a calorimeter. The simplest calorimeter consists of a thermometer attached to a metal container full of water and is suspended above a combustion chamber. In a typical calorimetry experiment, you can measure the energy that is released from fuels. Can you think why this might be important? The answer is that different fuels release different amounts of energy. So if you are flying a plane, you need a fuel which releases more energy than say if you were driving a car. This is because the plane is heavier than the car, so more energy is needed to make it move. In the classroom, if you do this experiment, you would do it on a much smaller scale, using a spirit burner. This is what you would need to do. One, you would measure the mass of the spirit burner before the experiment. Two, add a certain amount of cold water into a copper calorimeter, a small metal can, and suspend it at a fixed distance from the spirit burner. Can you think why it is important for it not to be too far away? Pause the video and continue when ready. The answer is that in this sort of experiment, a lot of the heat is transferred to the surroundings. So you need to minimize this by either placing the spirit burner as close to the calorimeter as possible, or you could reduce this by insulating the sides and adding a lid. Three, you'd measure the starting temperature of the cold water. Four, you'd use the spirit burner to heat the water for a fixed amount of time. Five, record the mass of the burner afterwards, so that you could calculate the mass of the fuel combusted. And finally, six, record the temperature change of the water caused by heating. Can you think why you might do the experiment more than once? Pause the video and continue when ready. The correct answer is that you want your results to be as accurate as possible. This also improves the reliability of the results you collect. If you have a larger temperature change on doing this experiment with one type of fuel than another, this means that more heat energy was transferred to the water than if you have a smaller temperature change. The best fuel is likely to release more energy per gram of fuel. In summary, calorimeters are devices that can measure the heat of chemical reactions, physical changes, or heat capacities for different materials. A simple experiment showed how measuring the temperature change of water could be used for this purpose. The larger the temperature change per gram of fuel, the more energy released.