Question

What is thermochemistry?

Answer 1

Hint: Thermochemistry is the branch of chemistry which involves the study of heat and energy related to chemical reactions and physical transformations. During a reaction, energy can be released or absorbed and there is a change in phase like melting or boiling.

Complete answer:
Thermochemistry mainly deals with the exchange of energy with its surroundings. It is used to find whether a chemical reaction is favorable or unfavorable, spontaneous or nonspontaneous. It helps in determining the quantities of products and reactants in a chemical reaction. When a chemical reaction takes place, the bonds between the atoms are broken and are formed again. Energy is necessary to form bonds and energy is released when bonds are formed. The energy is generally in the form of heat. The amount of energy used and released is different for different chemical reactions. The reaction is said to be endothermic if the energy released is less than the energy it takes from its surroundings. The reaction is said to be exothermic if the energy released is greater than the energy it takes from its surroundings. Combustion reactions release heat into surroundings and this energy is higher than the energy used from surroundings. The study of all these processes and the factors involved is called thermochemistry.

Note:
There are two fundamental principles of thermochemistry: The energy change associated with any process is equal and opposite to the reverse process and the energy change for a series of stepwise reactions is same as that of the entire process.