Question

What are chemical reactions that absorb energy?

Answer 1

Endothermic reactions

Explanation:

An endothermic reaction is a chemical reaction that takes in energy from the surroundings. The opposite of an endothermic reaction is an exothermic reaction. Reversible reactions are where the products can react to remake the original reactants. The energy is usually transferred as heat energy: the reaction absorbs heat. The temperature decrease can sometimes be detected using a thermometer.
Some examples of endothermic reactions are:

-photosynthesis
-the reaction between ethanoic acid and sodium carbonate
-dissolving ammonium chloride in water

You can read the wikipedia article for more information.