How is energy transformed?

The main forms of energy change in chemical reaction;

① Chemical energy and thermal energy

② Chemical energy and electric energy.

③ Chemical energy and light energy.

Reasons for energy conversion of chemical reaction: The essence of chemical reaction is the process of breaking chemical bonds in reactant molecules and forming new chemical bonds. The fracture of old bonds needs to absorb energy, and the formation of new bonds needs to release energy.

In general chemical reactions, the total energy absorbed by the old bond breaking is not equal to the total energy released by the formation of new bonds. This difference is the change of energy in the reaction, so there will be changes in energy during the chemical reaction.

Extended data

Calculation formula of energy change:

1, internal energy angle-theoretical method

▲E=E is born -E is reversed.

Where ▲E represents the change of energy in chemical reaction, e represents the total energy of products, and e represents the total energy of reactants.

① If ▲E=E is born -E is reversed > 0, the reaction absorbs energy (endothermic).

② If ▲E=E is born -E is reversed.

2. Bond energy angle-experimental method

For reactions involving only ideal gases: ▲E=E old -E new.

Where ▲E represents the change of energy in chemical reaction, e old represents the energy absorbed by all old bonds of reactants from the environment, and e new represents the energy released by all new bonds of products.

① If ▲E=E Old -E New > 0, it means that the reaction absorbs energy (endothermic).

② If ▲E=E Old -E New

Note: the energy change of chemical reaction is mainly realized as heat change, and q is often used instead of ▲ e.

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