2.32 describe an experiment to investigate the energy content in a food sample

 Calorimetry is basically burning food to obtain its energy content.

Method

- Obtain a food that will burn easily (e.g dry substance, like peanuts)
- Weigh a small sample of the food
- Skewer the sample on a mounted needle
- Add 25cm³ of water to a boiling tube held above the sample (with a clamp) - this will be used to measure the amount of heat energy is released when the food burns
- Measure the temperature of the water, then set fire to the food (using a bunsen burner)
- Hold the food sample directly under the boiling tube until it goes out, then relight it and repeat. Keep repeating until the food will not light anymore
- Measure the temperature of the water again.

NOTE: ensure the bunsen burner is not near the boiling tube, as this may create anomalies

Calculations

STEP 1: To calculate the energy content in Joules, substitute your results into this equation..

energy in food (J) = Mass of water (in g) x temperature change of water (in ºC) x 4.2

NOTE: 1cm³  of water is the same as 1g of water


STEP 2: calculate the amount of energy in Joules per gram

energy per gram of food (in J/g) = energy in food (in J) / mass of food (in g)