Exothermic and Endothermic

[J_CHEN 4I]

Why is the value of an exothermic reaction negative and why is the value of an endothermic reaction positive?

[Clarice Chui 2C]

When a reaction releases energy, or when it is exothermic, the value is negative. When the reaction absorbs energy, or is endothermic, the value is positive.

[Eesha Chattopadhyay 2K]

Exothermic reactions have a negative delta H because the enthalpy of the products have less enthalpy than the reactants, and delta H is the difference between the products and the reactants, making the delta H negative. In endothermic reactions the products have a higher H than the reactants, making delta H positive.

[RasikaObla_4I]

Because an exothermic reaction releases energy and the energy of the products is lower than the energy of the reactants, the enthalpy is negative. An endothermic reaction absorbs energy so the energy of the products is higher than the energy of the reactants, so the enthalpy is positive.

[Noe BM 1J]

An exothermic reaction has a negative H value because it releases energy when bonds are being formed. An endothermic reaction has a positive H value because it needs energy in order to break bonds.

[Shimei_2F]

Exothermic reactions have a negative value because it releases energy so products are lower than reactants. Vice versa for endothermic reactions which have a positive value because it requires energy so the reactants are lower than the products.

[rohun2H]

Delta H is the enthalpy of products minus the enthalpy of reactants.

[Rafsan Rana 1A]

Exothermic is negative because it is releasing energy, while endothermic is positive because it is absorbing energy

[Morgan Carrington 2H]

The negative and positive values are in reference to the release and absorption of heat from the perspective of the system itself. Releasing heat produces a negative sign and absorption a positive.

[Kaylee Clarke 1G]

the different in the sign values is a result of the action that occurs. so, for exothermic, since it releases heat, it will be negative. and because endothermic absorbs heat, it will be positive.

[alex_4l]

Exothermic is negative due to the fact that it is releasing energy and endothermic is positive due to the fact that it absorbs energy

[gabbymaraziti]

The enthalpy for an exothermic reaction is negative because the system/reaction loses energy, and the surroundings gain energy. Similarly, an endothermic reaction requires energy, so the enthalpy value is positive.