Science Common Sense
1729 - What types of reaction heats are commonly known, including molar heat of combustion and molar heat of formation
There are several types of reaction heats that are commonly known. These are:
- Molar Heat of Combustion: This is the amount of heat released when one mole of a substance is completely burned in oxygen. It's like measuring the energy released when gasoline burns in a car engine.
Example: The molar heat of combustion of gasoline is about -5460 kJ/mol. This means that when one mole of gasoline is burned, it releases 5460 kilojoules (kJ) of energy.
- Molar Heat of Formation (ΔHf): This is the amount of heat released or absorbed when one mole of a substance is formed from its individual elements in their standard state. It's like measuring the energy needed to build a LEGO castle from individual bricks.
Example: The molar heat of formation of water (H2O) is about -286 kJ/mol. This means that when one mole of hydrogen gas and half a mole of oxygen gas are combined to form water, 286 kilojoules of energy are released.
Molar Heat of Neutralization: This is the amount of heat released when one mole of an acid reacts with one mole of a base to form a salt and water. It's like measuring the energy released when a certain type of medicine (an acid) reacts with a base (like baking soda) in your stomach.
Molar Heat of Solution: This is the amount of heat released or absorbed when one mole of a substance is dissolved in a solvent (like water). It's like measuring the energy change when sugar dissolves in your morning cereal.
These are some of the most common types of reaction heats, but there are others like molar heat of fusion, molar heat of vaporization, and so on.