The large number of areas covered by the chemical energetics can be explained by the different forms in which chemical energy can be released: heat and combustion work, electrical energy in electrochemistry, radiant energy in chemiluminescent systems.
The chemical energy provided by a reaction reflects the energy balance associated with the electronic modifications suffered by the species involved.
From an energy point of view, a chemical reaction between molecules can be schematized in two stages. The first requires a supply of energy and corresponds to the rupture of the bonds of the reactant molecules with release of the atoms which constitute them.
The second releases energy and concerns the creation, by recombination of these atoms, of new bonds entering the structure of the reaction molecules.
As a general rule, the energy released in the second stage is greater than the first. We are talking about exothermic reaction. The difference between these two energies (reaction enthalpy) measures the amount of chemical energy transferred to the external environment.
It is conceivable that this quantity translates, not only the number, but also the strength of the connections involved.
A closed system is a system that makes no physical or chemical exchanges with its environment. Of these systems provided as choices (tree, human, clock, car), only a clock does not make exchanges with the environment, except for energy.
Therefore, of that list, only a clock would be a closed system.
Hope that helped! =)
The natural selection is the survival of the fittest, which means that o<span>nly the best adapted individuals survive and reproduce, contributing the most to the next generation</span>
According to natural selection, birds such as cardinals , eagles, and ducks have differently shaped feet due to <span>adaptation to different environments and feeding habits.
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The right answer is smelly garbage.
Infestation is the penetration into the body of a parasite whose nature is not microbial.
smelly garbage is not synonymous of infestation, because the olfactory system only detected smelly metabolites of these microorganisms. This does not necessarily mean that the microorganism has managed to penetrate the body.
By cons other proposals are signs and tools for infestation (torn packaging with food leaking out, dead insect bodysuits, feathers, and fur).
