Question

In an exothermic reaction, $$\mathrm{\Delta }H$$ is:
A.Positive
B.Negative
C.Zero
D.All

Answer 1

Hint: Energy changes are present in all chemical reactions. A reaction either releases or absorbs energy from its surroundings as it progresses. These two types of reactions are characterised as exothermic and endothermic, respectively, in thermodynamics. The prefixes endo- and exo- provide a quick way to recall the distinction between these two response types: endo- means to draw in, while exo- means to give out.

Complete answer:
Enthalpy (H) is a unit of measure for a system's total energy, and it's used to quantify and simplify energy transmission across systems. We most commonly refer to the change in enthalpy for a specific chemical reaction since the overall enthalpy of a system cannot be determined directly. The heat given out or absorbed in a chemical process is equal to the change in enthalpy at constant pressure. The change in enthalpy,$\mathrm{\Delta }H$, is commonly referred to as the "heat of reaction" because of this relationship.
Exothermic reactions are those in which energy is released, generally in the form of heat or light. Because the total energy of the products is less than the total energy of the reactants, energy is released in an exothermic reaction. As a result, the change in enthalpy for an exothermic process, $\mathrm{\Delta }H$ will always be negative. A strong acid will dissociate fast and produce heat in the presence of water, resulting in an exothermic reaction. Reaction that is exothermic The total energy of the products in an exothermic reaction is less than the total energy of the reactants. As a result, the enthalpy change is negative, and heat is discharged into the environment.

Note:
Because the internal energy of a system comprises components that are unknown, difficult to access, or not of interest in thermodynamics, the total enthalpy of a system cannot be measured directly. In practise, because it simplifies the explanation of energy transfer, a change in enthalpy is the preferred phrase for observations at constant pressure. At constant pressure, the enthalpy change equals the energy exchanged with the environment via heat when matter transport into or out of the system is likewise blocked.