Provide an example of the heat of combustion and heat of formation.

Heat of combustion is the energy released when a substance is burned in the presence of oxygen.

The heat of combustion is a measure of the energy released when a substance is burned in the presence of oxygen. This energy is typically measured in units of joules or kilojoules per mole of substance. For example, the heat of combustion of methane is -890 kJ/mol, which means that when one mole of methane is burned in the presence of oxygen, 890 kJ of energy is released.

The heat of formation, on the other hand, is the energy required to form one mole of a substance from its constituent elements in their standard states. This energy is also typically measured in units of joules or kilojoules per mole of substance. For example, the heat of formation of water is -285.8 kJ/mol, which means that it takes 285.8 kJ of energy to form one mole of water from its constituent elements (hydrogen and oxygen) in their standard states.

Both the heat of combustion and the heat of formation are important in understanding the energetics of chemical reactions. The heat of combustion can be used to calculate the amount of energy released in a combustion reaction, while the heat of formation can be used to calculate the energy required to form a particular substance. These values can also be used to predict the feasibility of chemical reactions and to design more efficient chemical processes.