This term is actually the key to understanding the difference between heat and the work involved in photosynthesis.
The heat you’ll get from photosynthesis is an endothermic process. Photosynthesis is an exothermic process. Endothermic processes are basically the opposite of the heat you’ll get from photosynthesis. For example, the heat you’ll get from a fire is an endothermic process.
Endothermic processes are also called thermodynamics. Thermodynamics is a branch of science that tells us how the world works from the point of view of heat. If you are looking at a fire and trying to figure out how to heat it, you are really making a decision based on how long your fire burns for. In thermodynamics, you are deciding how long it takes for the heat from your fire to move through the air to its destination.
Thermodynamics is the branch of science that tells us how the world works from the point of view of heat. In thermodynamics, you are deciding how long it takes for the heat from your fire to move through the air to its destination.
The problem is, is that while your fire is burning, you are not actually in one place. There is no heat moving through the air. Not the heat from the fire, and not necessarily the heat from the other fire. But since you are not actually in one place, you are not really making a decision about where the heat is going. It is happening outside of you.
When we say that photosynthesis is exothermic, we mean that the process of converting sunlight energy into chemical energy that is used to create new molecules is exothermic. We are not talking about the process of converting the heat of a fire into chemical energy. The process of creating new molecules is endothermic.
It’s endothermic because all the chemical energy is going into doing nothing. The process is exothermic because the chemical energy is going into creating new chemical energy that does work. You don’t get to do anything about it. It is not an argument against “if it’s endothermic, why do we care?”, it’s just saying that we don’t care when the heat is being used for something.
The good news is that photosynthesis is not an energy intensive process, so it gives you the chance to use the heat of your fire without any expense. The bad news is that the chemical bonds that make up the molecules of your food and your fire fuel come from something that is a process that takes time and energy, and so is not an energy efficient process.
So why do you care? I’m not saying you shouldn’t care (I’m not saying you should, I’m saying you should care), but there is a difference between “I don’t care” and “I don’t care because I don’t have to.
So, the question is, if you have a fire in your fireplace and you want to get as much heat as you can from it, why not just turn it into a chemical reaction? Well, you know that you will use up a lot of fuel and energy, and eventually it will stop working because the energy you’ve used up is still there.