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INTRODUCTION
Calorimetric analysis is a technique used to measure the amount of heat involved in a chemical or physical process. It involves the use of a calorimeter, which is a device designed to accurately measure heat changes.
Calorimetric analysis is based on the principle of energy conservation, which states that energy cannot be created or destroyed, only transferred or converted from one form to another. By measuring the heat changes associated with a process, calorimetry allows us to determine various thermodynamic properties, such as heat capacity, enthalpy change, and heat of reaction.
Although, the energy is not destroyed nor created in either of the cases; the total energy of the universe remains constant at all times;
Energy just transfers from one place to another;
There are 2 types of reactions:
- Exothermic– heat is released during the reaction; If the energy is lost during the reaction, it is an exothermic reaction – meaning that the energy gives the energy to its surroundings. As a result, the temperature is increased; therefore, the heat is released in the reaction;
- Endothermic – heat is absorbed during the reaction. If the energy is gained during the reaction, it is an endothermic reaction – meaning that the reaction gets the energy from its surroundings. In such cases, we have to provide energy (usually in a form of heat) which can be absorbed during the reaction for the chemical process to occur.
Let’s consider the energy level diagrams (also referred to as the reaction profiles) for exothermic and endothermic reactions:
As you can see, in the case of exothermic reaction, products at the beginning of a reaction have high potential energy and the energy is decreased as the reaction progresses. The difference between the energies of reactants and products is the energy that is released during the reaction. But still, there is a minimum energy required for a reaction to progress. This minimum energy is referred to as the activation energy.
Endothermic reaction is the opposite of exothermic reaction that we have just discussed. In the case of endothermic reaction, reactants have very low potential energy; therefore, they need the input of energy (activation energy) for the reaction to progress. As a result, the products that are obtained in a reaction have high potential energy. The difference between the energies of reactants and products is the energy that is absorbed during the reaction.
Thermal Energy, Temperature, and Heat
Thermal Energy is a form of kinetic energy associated with the random motion of atoms and molecules. Increasing the amount of thermal energy increases the temperature of the system and vice versa.
The transfer of thermal energy between two borders with different temperatures is referred to as Heat (q). Transfer of heat always occurs from a subject with higher kinetic energy to subject with lower kinetic energy.
Energy is measured in units of Calories (cal). 1cal is the amount of energy required to increase the temperature of 1g of water by 1oC or 1K.
The SI unit of heat, work, and energy is the Joule (J). 1J is the amount of energy used to move an object for 1meter with a force of 1newton.
1cal = 4.184J