When hydrogen gas reacts with oxygen gas under certain conditions to produce liquid water, 572.0 kJ of heat energy is released. Is the reaction exothermic or endothermic?

Answer : This reaction is an exothermic reaction.

Explanation :

Endothermic reaction : It is defined as the chemical reaction in which the energy is absorbed from the surrounding.

In the endothermic reaction, the energy of reactant are less than the energy of product.

Exothermic reaction : It is defined as the chemical reaction in which the energy is released into the surrounding.

In the exothermic reaction, the energy of reactant are more than the energy of product.

Enthalpy of reaction : It is the difference between the energy of product and the reactant. It is represented as .

The balanced chemical reaction will be:

From the reaction we conclude that the heat energy is released during the reaction that means this reaction is an exothermic reaction.

Hence, the reaction is an exothermic reaction.