endothermic and exothermic

[405669838]

How can we tell based off an equation whether the reaction is endothermic or exothermic?

[Elsie_Lin_2K]

In exothermic reactions, the delta H value would be less than 0, in other words, heat would be produced as a product. On the other hand, in an endothermic reaction, delta H would be greater than 0 which would mean that heat would be produced as a reactant rather than a product.

[kylanjin]

A delta H value of less than 0 would make the reaction exothermic, while a delta H value of greater than zero would make the reaction endothermic. You can also qualitatively determine this by looking at if bonds are being formed or broken in the reaction. Forming bonds releases energy (exothermic), while breaking bonds requires absorbing energy (endothermic).

[Sristi Palimar 2E]

In endothermic reaction, energy is being absorbed, therefore deltaH is a positive value. Conversely, in exothermic reactions, energy is being released, therefore deltaH is a negative value. An easy way to remember this distinction is by paying attention to prefixes: "exo" means "outer", so as to imply "giving off"; "endo" means "within", so as to imply absorption.

[Emily Nguyen 3L]

In CHEM 14B, you are almost always given the value of delta H, which can either be positive (endothermic) or negative (exothermic). If you're given a graph, endothermic reactions show an increase in enthalpy while endothermic reactions show a decrease in enthalpy.

[Holly Do 2J]

We can tell whether an equation is endothermic or exothermic if we are given the delta H value. If delta H is a positive value the reaction will be endothermic because it requires heat whereas if the delta H is a negative value the reaction is exothermic because it releases heat.

[Madison Nguyen 3L]

An exothermic reaction is indicated best by a negative delta temperature, indicating a release of heat and a need to cool down, whereas endothermic requires heat, meaning the change in temperature (delta) will be positive.

[Sarah Hong 2K]

Endothermic reactions absorb energy/heat whereas exothermic releases energy/heat, so endothermic reactions have a positive deltaH and exothermic reactions have a negative deltaH.

[Jillian Sarquiz- 2B]

You would look at the delta H (which should be given). If the delta H is positive, then the reaction is endothermic. If the delta H is negative, then the reaction is exothermic.

[Aaron Kwan 3B]

Because delta H is less than zero, the change in energy to the system is negative. If the system lost energy, then the energy must have come out of the system (as heat), meaning the system is exo-thermic.

Similarly, if delta H is more than zero, the change in energy to the system is positive. Thus, the system gained energy, which means it must have sucked energy from outside into the system. The system is endo-thermic.

This is how I remember the difference!

[Natalie Coughlin 1I]

In order to tell if a reaction is endothermic or exothermic, we look at the given delta H value. If it is positive, the reaction is endothermic, and if it is negative, the reaction is exothermic.

[Hannah Thornton 1F]

An exothermic reaction would have a delta H value of less than zero, meaning heat/energy is being
released. An endothermic reaction would be a delta H value of greater than zero, meaning heat/energy is being absorbed.

[Anne Hogue 2J]

If the reaction gives a net release of heat meaning delta H is negative, then the reaction is exothermic. If the reaction requires heat, meaning delta H is is positive, then the reaction is endothermic.

[loganchun]

The amount of heat released or absorbed at a constant pressure is called enthalpy. If the reaction gives a net release of heat, the reaction is exothermic. If the reaction requires heat, the reaction is endothermic.

[Minoo Bastani 2J]

The only way we would be able to tell if a reaction is exothermic or endothermic is if heat is either featured in the reaction as a reactant or product, or if you are given a Delta H value (enthalpy). If heat is a reactant or the Delta H is positive, the reaction is endothermic. If heat is a product or Delta H is negative, the reaction is exothermic.