Exothermic vs. Endothermic reactions

[Noe BM 1J]

Does anyone know if we will be asked on the test whether a reaction is exothermic or endothermic? If so, will the delta H value be given to us?

[Julie_Reyes1B]

Yes, it can be asked in terms of Le Chatelier's principle. I.e. what happens when you raise the temperature on an endothermic/exothermic reaction. They might give you a reaction and then ask whether it is endothermic or exothermic, then ask questions about Le Chatelier's. For this, they would have to give you a ∆H value.

[Wendy 1E]

It is possible. All I suggest knowing is that when delta H is positive, the reaction is endothermic and when delta H is negative, the reaction is exothermic.

[Matthew Tsai 2H]

A question that asks if a reaction is endothermic or exothermic should provide delta H, in which if delta H is positive, the reaction is endothermic and if it is negative, the reaction is exothermic.

[Junwei Sun 4I]

It is possible in the context of the Le Chatelier's principle. For example how will the equilibrium shift if temperature is increased/decreased given a reaction is endothermic or exothermic.

[Caroline Beecher 2H]

It is also good to note that when a reaction requires heat (endothermic) while forming product, then heating will favor product formation. When a reaction gives off heat (exothermic) while forming product, then heating will favor reactant formation.

[LNgo 1G]

If it is asking about temperature effects/changes, I would assume that either endo/exothermic or the delta H value will be given and you can determine the other by knowing that exothermic reactions have a negative delta H value and endothermic reactions have a positive delta H value.

[Abby Soriano 1J]

You should expect to know how to determine if a reaction is exothermic or endothermic based on the value of delta H (a negative value signifies an exothermic reaction), the reaction's response to added heat (does the addition of heat cause the reaction to favor the left or right), and the stability of the reactants and products.

[Celena Kim 2I]

Yes, the problem will typically give you delta H when asked if the reaction is exothermic or endothermic.

[Diana Andrade_4F]

Yes, you should be able to determine if the reaction is exothermic or endothermic when given delta H.

[Connor Chappell 2B]

The problem given on the tests gives you the chemical equation and the delta H value (change in enthalpy) and you are asked whether the reaction is endothermic or exothermic. If delta H is negative, the reaction is exothermic, and the contrapositive is true.

[Madelyn Romberg 1H]

From our current tools given, he will give the change in enthalpy and from that information you will have to determine if it is exo/endo, and he may ask questions that utilize Le Chateliers principle in regards to temp.

[MTanikella_1K]

It is a fair question to expect on Test 1. If a reaction is exothermic, delta H will be negative as heat is released while a reaction that is endothermic will have a positive delta H as heat is needed.