Can a physical change reverse a chemical change?

Physical change can not restore chemical change. This is because chemical changes lead to the formation of new substances. The chemical bond is broken, and a new bond is formed between different atoms. To break new bonds and reform existing bonds, another chemical change is necessary.

Even if a physical change occurs, the chemical composition of the substance does not change. Some examples of physical changes are melting, freezing, evaporation and condensation. Physical changes can be reversed by heating or cooling the material without destroying or forming chemical bonds.

As long as sufficient energy is not supplied to break chemical bonds, the water formed during the reaction can not be converted to hydrogen and oxygen, which will change the chemical formula.

This is a physical reaction. There is no change in the chemical formula of the substance. By cooling liquid water, it can return to a solid state, so that the chemical formula does not change yet.

All chemical reactions are reversible, but this is actually difficult. Many junior high school science textbooks say that chemical changes can not be restored, but physical changes can be restored. Cutting paper and crushing rocks is noticeable as a physical change, but it is difficult to restore the original paper and rock. Rechargeable batteries use chemical reactions during discharge. Recharging involves driving the reaction in the reverse direction to return the product to the original reactant. When the car's engine is running, the car's generator (alternator) is always charging the car's battery.

Students usually think that the physical change is reversible, but the chemical change is not. Students also believe that the first problem of chemical reaction will disappear completely and disappear forever. Common day-to-day applications of reversible chemical reactions are charging and discharging of rechargeable batteries including automotive batteries, but it is not a chemical substance that converts chemical energy to electric energy, but a battery is a means of storing electricity You might think.

Even if a physical change occurs, the chemical composition of the substance does not change. Some examples of physical changes are melting, freezing, evaporation and condensation. Physical changes can be reversed by heating or cooling the material without destroying or forming chemical bonds.