Photochemistry is the branch of chemistry which is mainly concerned with rates and mechanisms of reactions resulting from the exposure of reactants to light radiations. The photochemical reaction is, in fact, the thermal reaction of the electronically excited state of the molecule while the dark reaction of the molecule is the thermal reaction of the ground state.
What is Photochemical Reaction?
A photochemical reaction is a chemical reaction triggered when light energy is absorbed by a substance’s molecules.
This response leads the molecules to experience a temporary excited state, thus altering their physical and chemical properties from the substance’s initial molecule.
Photochemical Reaction Definition
“The photochemical reaction is none other than a chemical reaction that starts with light being absorbed as a form of energy”. Temporary peak states would be triggered while the molecules absorb light and there would be physical and chemical property differences to a large extent from the real molecules.
The resultant chemical structures could be separated, modified, mixed among the similar or different molecules along with the transfer of hydrogen atoms, electronic charge to separate molecules, protons, and electrons. The peak states in comparison to the real ground states are stronger reductants and acids that are stronger.
The mechanism of a photo reaction should ideally include a detailed characterization of the primary events as outlined by the classification of photochemical reaction pathways. The quantum yields and hence the rate constants of all relevant photophysical and photochemical processes, in addition to the information about the structure and fate of any reactive intermediates, their lifetimes and reactivities.
Photochemical Reaction in Photosynthesis
- Photosynthesis is the final property of the process that is one of the widely discussed topics in the world as it sustains the life on planet Earth.
- Photosynthesis is a photochemical process by which green plants, seaweeds, algae, and certain bacteria absorb solar energy and utilize it to convert the atmospheric carbon dioxide to carbohydrates in the presence of water.
- Using photosynthesis, plants would convert the sunlight energy into the chemical energy being stored and thereby form carbohydrates using water and carbon dioxide and releases oxygen as a by product of the reaction.
- Animal life is sustained with the aid of oxygen and carbohydrates.
Photochemical Reaction Examples
The majority of processes on the other hand that we see in nature are photochemical ones. Our own ability to see the things in the world using the eyes is nothing but a photochemical reaction where a retinal that happens to be rhodopsin (photoreceptor cell molecule) changes its shape after sunlight or light absorption.
- Vitamin D which is required for bone and teeth development and even functioning of Kidney while helping skin growth is the chemical 7-dehydrocholesterol produced after exposure to sunlight.
- The ozone layer that is found in the earth’s stratosphere is formed by the photochemical dissociation of molecular oxygen into oxygen atoms and these atoms reacting with molecules of oxygen to form ozone.
- The Ultraviolet (UV) rays that are harmful to human DNA and skin cancer likes are caused by photochemical reactions.
- Different sorts of commercial processes and devices are heavily influenced by photochemical reactions and their peak states.
- Activities that we encounter in our daily lives like xerography, photography and so on are based on photochemical processes whereas complex activities like manufacturing of semiconductor chips, the printing of newspapers are done by the aid of UV rays.
- The examples explained above would have given you a fair idea about how chemical reactions like the photochemical ones have a major impact on our daily lives without which it would be impossible for life to sustain on our planet.
Frequently Asked Questions
What is a photochemical reaction example?
Photosynthesis: plants convert carbon dioxide and water into glucose and oxygen using solar energy. Human vitamin D production by sunlight exposure. Bioluminescence: for example. An enzyme in the abdomen catalyses a light-producing reaction in fireflies.
What is the primary photochemical process?
Photolysis is the process by which a photochemical reaction is performed. The immediate consequence of light absorption is a primary photochemical reaction. Secondary reactions are termed subsequent chemical shifts.
What starts a photochemical reaction?
Photochemical reaction, a chemical reaction caused in the form of light by the absorption of heat. The consequence of the absorbing light of molecules is the development of transient excited states with chemical and physical properties that differ greatly from the original molecules.
What is photochemical dissociation?
Photodissociation, photolysis, or photo decomposition is a chemical reaction where photons break down a chemical compound. It is defined as one or more photons interacting with a single target molecule. There is no limited photodissociation to visible light.
What is the photochemical equation?
Photochemical equivalence law, fundamental principle relating to light-induced chemical reactions, which states that one molecule of the material responds to each quantity of radiation that is absorbed.
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