How do you determine a reaction that is endothermic?

1 Answer
Aug 19, 2016

Do you mean, "How to determine if a reaction is endothermic"?


Endo means "into" so, if a reaction is endothermic, heat must be added during the reaction.

Here are some ways to determine if a reaction is endothermic.

1. Look at the information given

If the equation has "energy" or "heat" on the left hand side of the reaction arrow, the reaction is endothermic. An example is,

#"6CO"_2 + "6H"_2"O" + "energy" → "C"_6"H"_12"O"_6#

2. Look at the energy diagram for the reaction.

If the products are at a higher energy level than the reactants, the reaction must have absorbed energy.

3. Do an experiment

If you have to heat the reactants to keep the reaction going or if it cools down during the process, the reaction is endothermic.

4. Do a calculation

As a last resort, you can calculate the amount of energy needed to break all the bonds in the reactants and the amount of energy released when you form the new bonds in the products.

If you get back less energy than you had to put in, the reaction is endothermic.