A person is out on the beach for about 1 hour without sunscreen. The amount of UVA radiation hitting a surface at sea level on a slightly clouded day is about 80W/m². About half of that can be absorbed by the skin. Estimate the number of C-C bonds broken in this person's back (about 0.24 m²) over that period. A typical carbon-carbon bond requires 348 kJ/mol to break. Assume that the average wavelength of UVA is 335 nm.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
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