The reaction 4al (s) 3o2 (
g. → 2al2o3 (s) δh° = -3351 kj is and therefore heat is by the reaction.

The reaction is exothermic and therefore the heat is released by the reaction.

Explanation:

There are 2 types of reaction based on the heat of the reaction:

Exothermic reactions are defined as the reactions in which energy is released in the form of heat. The enthalpy change of the reaction comes out to be negative for this kind of reaction.Endothermic reactions are defined as the reactions in which energy is absorbed in the form of heat. The enthalpy change of the reaction comes out to be positive for this kind of reaction.

For the given chemical reaction:

As, the enthalpy change of the reaction is negative. The reaction is considered as an exothermic reaction.

Hence, the reaction is exothermic and therefore the heat is released by the reaction.

A synthesis reaction occurs when two or more reactants combine to form a single product.

In a decomposition reaction, one reactant breaks down into two or more products. ...

Replacement reactions occur when elements switch places in compounds.

Explanation: