Question

Hi everyone. I just finished a warm-up on my online course and I did okay. However, I am not sure how to differentiate between right and wrong.

The question is below:

http://i288.photobucket.com/albums/ll172/Chloe_Crull/Chem1_zps8d71b19e.png

I'm sorry for the Photobucket upload; I am not sure how to URL it otherwise. I use Edgenuity.

Anyway, how can I determine if it is exothermic or endothermic based on a chemical equation? Also, how do I know if heat is a reactant?

Thanks!

Edit: I already know the answer as it is a warm-up practice. I would appreciate a detailed explanation. (:

Answer 1

how can I determine if it is exothermic or endothermic based on a chemical equation? Also, how do I know if heat is a reactant?

Heat as a reactant = endothermic
Heat as a product = exothermic

Answer 2

Simple as that.

Answer 3

Heat as a reactant:

1) After the reaction occurs, the temperature decreases.
2) If you have to add heat to START a reaction.

Answer 4

Thanks! I also wrote down that delta H < 0 = product and delta H > 0 = reactant.

However, how do i know that heat is present when i look at the chemical equation?

Answer 5

Yeah, you can use Enthalpy too

Answer 6

Thank you (: