Endo or exo thermic? Work??

Question

IS the reaction of Zn(s) + 2HCl (aq) --> ZnCl2(aq) + H2(g) exo or endo thermic? Is work done by the system or on the system? Or none?

Answer 1

Endothermic is when the enthalpy or (Delta H) is positive where Energy is absorbed during the reaction.
The graph from and endothermic reaction is where the Reactants and BELOW the Products (going UPHILL!) which means it has stronger bonds with each other and required MORE energy to break the bonds and create the products. Because so much energy is used for this reaction it absorbs heat (another form of energy) from the surrounding (hence making the tempreture in the surrounding to drop, or become colder) to remember endo as +ve just think u have to ADD energy for the reaction. to remember the graph, think how much energy u need to go UPHILL, hence more energy is needed for the reaction!


Exothermic is when the enthalpy is negative, where heat is being released during the reaction.
Exothermic is the total opposite. the reactants have very weak bonds with each other hence it's easier to break. = Less energy required. Think of running DOWNHILL

Well, just remember Endothermic, coz Exothermic is the total opposite! :)

Now to answer your question,
This reaction involves the Hydrochloric acid consuming Zn metal, therefore it is an exothermic reaction because its waste product is a salt (Zinc Chloride) and Hydrogen gas. Anything involving an acid corroding a metal is Exothermic, as in heat/energy is released!

Answer 2

Can't remember, seems to me that most reactions that give off Hydrogen gas are exothermic. Sorry, it's been a long time.

Answer 3

this is Exothermic reaction. "HCl is a strong Acide". and the reaction between Metals and Strong acides is exothermic.

Answer 4

as H2 is given out, the reactants need some heat to give out gases. hence it is endothermic