Why do endothermic reactions occur spontaneously?

For endothermic reactions, enthalpy usually goes up. However, a spontaneous endothermic reaction can occur when the changes in enthalpy and entropy yield a negative Gibbs free energy. An endothermic reaction can be spontaneous if entropy increases by more than the change in enthalpy.

Why do chemical reactions occur spontaneously?

A spontaneous reaction is a reaction that favors the formation of products at the conditions under which the reaction is occurring. The entropy of the system increases during a combustion reaction. The combination of energy decrease and entropy increase dictates that combustion reactions are spontaneous reactions.

Does exothermic processes are always spontaneous?

If a reaction is exothermic ( H is negative) and the entropy S is positive (more disorder), the free energy change is always negative and the reaction is always spontaneous.

Why are some reactions exothermic?

Chemical reactions that release energy are called exothermic. In exothermic reactions, more energy is released when the bonds are formed in the products than is used to break the bonds in the reactants. Exothermic reactions are accompanied by an increase in temperature of the reaction mixture.

What determines whether a reaction is spontaneous?

The two factors that determine whether a reaction is spontaneous are: Enthalpy: When the reaction gives off energy, then the reaction is said to be spontaneous. Entropy: It is the measure of randomness in a system. As the randomness of the reaction increases, the spontaneous is the reaction.

When a reaction is exothermic and entropy is positive the reaction is always spontaneous?

If entropy (disorder) increases, and the reaction enthalpy is exothermic ( ΔH<0 ) or weakly endothermic ( ΔH>0 & small), the reaction is generally spontaneous. A reaction will be spontaneous if the change in G , ΔG , is negative.

Which type of reaction is always spontaneous and exothermic reaction?

A reaction which is exothermic (ΔH negative) and results in an increase in the entropy of the system (ΔS positive) will always be spontaneous.

Why do endothermic and exothermic reactions happen?

When a chemical reaction combines two or more things and makes a chemical bond, energy is released, so it is an exothermic reaction. These reactions usually feel hot because heat is given off. If a reaction breaks one or more bonds, energy is needed, or consumed, so it is an endothermic reaction.

Are exothermic reactions spontaneous?

When a reaction is exothermic and the entropy increases throughout the reaction the reaction is spontaneous at all temperatures?

An exothermic reaction will always be spontaneous if the entropy increases. Spontaneous reactions have a ΔG <0 and that ΔG = H – TΔS (Δ= delta). So, an exothermic reaction that increases in entropy will always be spontaneous.

How entropy can be used to explain how a endothermic reaction can occur spontaneously?

An endothermic reaction can be spontaneous if entropy increases by more than the change in enthalpy. For endothermic r̥eactions, ΔH> 0 and thus if the value of −TΔS overshadows the ΔH value (usually at very high temperatures) then the overall value of ΔG becomes negative and thus the reaction becomes spontaneous.