This may look fairly complicated, but actually its simply just the composition of the elements. Here it is in word equation form.
Although this may be slightly biology related it is also chemistry related AND physics related. So we know that when we eat food, to get energy we require the substance glucose (which is a molecule in the food we eat) to be burned in oxygen to produce carbon dioxide and water as by-products. However, most importantly this reaction produces energy, namely in the form of heat. Firstly here is the chemical equation:C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H2O (l) ΔHc -2880 kJ
Glucose + Oxygen → Carbon Dioxide + Water (+ENERGY:- 2880 kJ to be precise)
kJ or kilojoules are basically a unit to measure energy in (1000 joules, as the prefix "kilo" implies, as in kilometres or kilograms). You may have also heard of calories being used, especially in terms of food. They can be directly compared.
4.1868 kilojoules = 1 Calorie
One calorie is the energy needed to raise the temperature of exactly one gram of water by one degree Celsius. So, one kilojoule is just 1/4 of that amount of energy approximately.
So, anyway, we know that when these materials are transported to the cells, this chemical reaction occurs, producing heat energy. The equations are balanced. The question is, where did the heat energy come from?
We know that it is theoretically possible to convert matter into energy (as described by Einstein's equation of E=MC^2), but obviously no matter has been converted into energy for three reasons:-
- The equations are balanced
- You'd need immense heats for this to happen which we can't even produce on earth. Imagine this type of heat in your body!
- If we actually could produce anything close to these types of heat in our bodies, it wouldn't exactly be gaining energy would it?
So just what happens to release this energy?
This question can be answered simply if you know about atoms. Atoms always try to gain the lowest energy levels possible, as energy is stored in their chemical bonds, to keep them joined together in compounds. Glucose is fairly happy as glucose and oxygen is quite content with itself too. Unfortunately for them, when they come together, they realise that there is a another state they would prefer to be in, namely in the rearranged forms of water and carbon dioxide. You can of course probably guess why...
They need less energy!
Another law states that energy cannot be destroyed (although it can be theoretically created from matter). So where has all the excess energy gone that is not needed any more?
It's released as heat energy in your body!
So that answers the question of where the energy came from, but also describes sort of what chemical energy is, and how that becomes heat energy. If you have any questions or corrections, just leave them in the comments.
