Experimentally, it is found that all spontaneous processes ( including chemical reactions ) result in a decrease in G as they proceed toward equilibrium.

However, this is not required ; endothermic reactions can proceed spontaneously if the TΔS term is large enough.

However, the law of mass action is valid only for concerted one-step reactions that proceed through a single transition state and is not valid in general because rate equations do not, in general, follow the stoichiometry of the reaction as Guldberg and Waage had proposed ( see, for example, nucleophilic aliphatic substitution by S < sub > N </ sub > 1 or reaction of hydrogen and bromine to form hydrogen bromide ).

In these papers, Gibbs showed how the first two laws of thermodynamics could be measured graphically and mathematically to determine both the thermodynamic equilibrium of chemical reactions as well as their tendencies to occur or proceed.

Non-spontaneous reactions run so slowly that they are considered to require the input of some type of additional energy ( such as extra heat, light or electricity ) in order to proceed to completion ( chemical equilibrium ) at human time scales.

As enzymes act as catalysts they allow these reactions to proceed quickly and efficiently.

Such reactions are thought to proceed via sulfenic acid intermediates.

These reactions proceed via the intermediacy of a carbamoyl chloride ( RNHC ( O ) Cl ).

By complex cooperative action the proteases may proceed as cascade reactions, which result in rapid and efficient amplification of an organism's response to a physiological signal.

Our understanding of how reactions proceed at the atomic level in the solid state was advanced considerably by Carl Wagner's work on oxidation rate theory, counter diffusion of ions, and defect chemistry.

Some solid state reactions already proceed at temperatures as low as 100 ° C.

The Gamow factor was used in the decade that followed by Atkinson and Houtermans and later by Gamow himself and Edward Teller to derive the rate at which nuclear reactions would proceed at the high temperatures believed to exist in stellar interiors.

Such reactions proceed via the intermediacy of metal carboxylate complexes.

The graph for these equations is a sigmoid curve, which is typical for autocatalytic reactions: these chemical reactions proceed slowly at the start because there is little catalyst present, the rate of reaction increases progressively as the reaction proceeds as the amount of catalyst increases and then it again slows down as the reactant concentration decreases.

This is generally not true in chemical reactions, where an ordered state may proceed towards a disordered state depending on thermodynamic parameters.

Photochemistry, a sub-discipline of chemistry, is the study of chemical reactions that proceed with the absorption of light by atoms or molecules.

Photochemical reactions are valuable in organic and inorganic chemistry because they proceed differently than thermal reactions.

Alkenes undergo many important reactions that proceed via a photon-induced π to π * transition.

Modern methodology is capable of not only allowing aldol reactions to proceed in high yield but also controlling both the relative and absolute stereochemical configuration of these stereocenters.

Substitution reactions that proceed through a free carbocation intermediate ( such as unimolecular substitution reactions ) lead to non-stereospecific addition of substituents which results in racemization.

While unimolecular elimination reactions also proceed through a carbocation, they do not result in a chiral center.

The attempts of alchemists to arrange information on substances, so as to clarify and anticipate the products of their chemical reactions, resulted in early conceptions of chemical elements and the first rudimentary periodic tables.

28 people reported apparent allergic reactions related to eating corn products that may have contained the Starlink protein.

Those elements that do not occur naturally on Earth have been produced artificially as the synthetic products of man-made nuclear reactions.

Chemical elements may also be categorized by their origin on Earth, with the first 98 considered to be naturally occurring, while those with atomic numbers beyond 98 have only been produced artificially as the synthetic products of man-made nuclear reactions.

These include some produced by cosmic rays or other nuclear reactions ( see cosmogenic and nucleogenic nuclides ), and others produced as decay products of long-lived primordial nuclides.

Catalytic reactions are preferred in environmentally friendly green chemistry due to the reduced amount of waste generated, as opposed to stoichiometric reactions in which all reactants are consumed and more side products are formed.

Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants.

Chemical reactions are described with chemical equations, which graphically present the starting materials, end products, and sometimes intermediate products and reaction conditions.

More elaborate reactions are represented by reaction schemes, which in addition to starting materials and products show important intermediates or transition states.

In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products.

As a result, products are formed faster and reactions reach their equilibrium state more rapidly.

In addition, some household products use enzymes to speed up biochemical reactions ( e. g., enzymes in biological washing powders break down protein or fat stains on clothes ; enzymes in meat tenderizers break down proteins into smaller molecules, making the meat easier to chew ).

An allergen associated with this type of reaction is peanut, although latex products can induce similar reactions.

Until recently the rates of reactions in interstellar clouds were expected to be very slow, with minimal products being produced due to the low temperature and density of the clouds.

These products produce effects similar to, but not the same as those of real Maroger medium, which depends on specific chemical reactions between leaded oil, mastic resin, and turpentine ( the mastic varnish vehicle ).

Molecular oxygen ( O < sub > 2 </ sub >) directly oxidizes many compounds to produce useful products in an organism, such as antibiotics, etc., in reactions catalyzed by oxygenases.

) can also be ensured resulting in more uniform reaction conditions and higher grade products in single and multi-step reactions.

Due to the formation of water as one of the products, these reactions are known as dehydration.

The desire in molecular nanotechnology would be to balance molecular reactions in positionally-controlled locations and orientations to obtain desired chemical reactions, and then to build systems by further assembling the products of these reactions.

Each metabolic pathway consists of a series of biochemical reactions that are connected by their intermediates: the products of one reaction are the substrates for subsequent reactions, and so on.