A chemical reaction is a process that transforms one set of
chemical substances to another. The study of chemical reactions is part of the
field of science called chemistry.
Chemical reactions can result in molecules attaching to each
other to form larger molecules, molecules breaking apart to form two or more
smaller molecules, or rearrangement of atoms within or across molecules.
Chemical reactions usually involve the making or breaking of chemical bonds,
and in some types of reaction may involve production of electrically charged
end products. Reactions can occur in various environments: gases, liquids,
solids, or combinations of same: for example, at interfaces.
As shown in the adjacent figure for a general case, the
participating reactants typically must surmount a threshold energy or
activation energy to initiate the reaction, and intermediates exist briefly
before the final products are formed. Changes in bonding of a single occurrence
of the transformation is not all that is involved in the energy depicted, which
is intended to show the evolution of an entire soup of reactants, intermediates
and products. This evolution typically involves generation of heat, physical
motion and mixing of all the participants, and the chemical reactions. In the
figure, the activation energy on the left indicates the change in all these
factors needed to surmount the activation threshold and the energy output on
the right indicates the change in these factors when the reaction is complete, being
the difference between the starting system with only the reactants themselves
and the ending system consisting only of the final products. This overall
change in energy may be made to do useful work, or simply be dissipated as heat
Chemical reactions can be either spontaneous and require no
input of energy, or non-spontaneousmwhich often require the input of some type
of energy such as heat, light or electricity. Classically, chemical reactions
are strictly transformations that involve the movement of electrons during the
forming and breaking of chemical bonds. A more general concept of a chemical
reaction would include nuclear reactions and elementary particle reactions.
In terms of the energy changes that take place during
chemical reactions, a reaction may be either exothermic or endothermic ...
terms which were first coined by the French chemist Marcellin Berthelot (1827 −
1907). The meaning of those terms and the difference between them are discussed
below and illustrated in the adjacent diagram of the energy profiles for
exothermic and endothermic reactions.
xothermic chemical reactions release energy. The released
energy may be in the form of heat, light (for example, flame), electricity (for
example, battery discharge), sound and shock waves (for example, explosion) …
either singly or in combinations.
A few examples of exothermic reactions are:
• Mixing of
acids and alkalis (releases heat)
• Combustion
of fuels (releases heat and light)
Endothermic chemical reactions absorb energy. The energy absorbed
may be in various forms just as is the case with exothermic reactions:
A few examples of endothermic reactions are:
• Dissolving
ammonium nitrate (NH4NO3) in water (H2O) (absorbs heat and cools the
surroundings)
• Electrolysis
of water to form hydrogen (H2) and oxygen (O2) gases (absorbs electricity)
• Photosynthesis
of chlorophyll plus water plus sunlight to form carbohydrates and oxygen
(absorbs light)
why chemical reactions can create molecules that are attached to form larger molecules?
BalasHapusbecause in chemical reactions usually involve the making or breaking of chemical bonds of a substance with other chemicals.
BalasHapuswhich is also influenced by several factors including: the environment, temperature and pressure.
I think the chemical reaction can create molecules that are attached to form larger molecules due to chemical reactions, each of the elements react to form compounds that always involves the formation of chemical bonds so that the molecules are attached to form larger molecules.
BalasHapusI think in a chemical reaction occurs that changes the molecular small molecules can be large and vice versa. Chemical reactions are also necessarily involve the making or breaking of chemical bonds, and in some kind of reaction may involve the production of the final product is electrically charged. The reaction can occur in a variety of environments: gas, liquid, solid, or a combination of the same: for example, at the interface.
BalasHapusin my opinion because its basic chemical reactions that would not take place if it is only one type of molecule, and the chemical reaction to create more basar uyang molecules from molecules start with a new name ...
BalasHapus