Question: Why is it important to make the reactions as efficient as possible?
About the article "Chemical reaction", section "Applications".

Candidate passages:
Chemical reactions are central to chemical engineering where they are used for the synthesis of new compounds from natural raw materials such as petroleum and mineral ores.
It is essential to make the reaction as efficient as possible, maximizing the yield and minimizing the amount of reagents, energy inputs and waste.
Catalysts are especially helpful for reducing the energy required for the reaction and increasing its reaction rate.
Some specific reactions have their niche applications.
For example, the thermite reaction is used to generate light and heat in pyrotechnics and welding.
Although it is less controllable than the more conventional oxy-fuel welding, arc welding and flash welding, it requires much less equipment and is still used to mend rails, especially in remote areas.
It is fundamental in chemical reactions of the form A+B→ C+D that two products are necessarily generated though product C may have been the desired one.
That being the case, D is considered a byproduct.
As it is a significant goal of green chemistry to maximize the efficiency of the reactants and minimize the production of waste, D must either be found to have use, be eliminated or be as insignificant and innocuous as possible.
With the new equation of the form A+B→C, the first step in making chemical manufacturing more efficient is the use of reactions that resemble simple addition reactions with the only other additions being catalytic materials. 
All species in the "Telescopus" genus are venomous, with the venom being of a neurotoxic nature, however they are not considered particularly harmful to man.
This is because the opisthoglyphous venom-delivery system is not as efficient as the delivery systems found in Elapids and Viperidae.
However, some members of the "Telescopus" genus such as "T. dhara" have particularly large venom glands, and the venom toxicity in some species has been compared to that of the "Acanthophis" species.
For these reasons it is advisable that all "Telescopus" species be handled with caution.
It is also important to consider that allergic reactions are possible after a bite, and such a reaction would significantly worsen the effects of an envenomation. 
Nearly all chemical reactions can occur at normal temperatures (although different reactions proceed at different rates).
However most reactions are accelerated by high temperatures, and the degradation of foods and pharmaceuticals is no exception.
The same applies to the breakdown of many chemical explosives into more unstable compounds.
Nitroglycerine is notorious.
Old explosives are thus more dangerous (i.e.
liable to be triggered to explode by very small disturbances, even trivial jiggling) than more recently manufactured explosives.
Rubber products also degrade as sulphur bonds induced during vulcanization revert; this is why old rubber bands and other rubber products soften and get crispy, and lose their elasticity as they age.
The usually quoted rule of thumb is that chemical reactions double their rate for each temperature increase of 10 degrees Celsius (°C) because activation energy barriers are more easily surmounted at higher temperatures.
However, as with many rules of thumb, there are many caveats and exceptions.
The rule works best for reactions with activation energy values around 50 kJ/mole; many of these are important at the usual temperatures we encounter.
It is often applied in shelf life estimation, sometimes wrongly.
There is a widespread impression, for instance in industry, that "triple time" can be simulated in practice by increasing the temperature by 15 °C, e.g., storing a product for one month at 35 °C simulates three months at 20 °C.
This is mathematically incorrect (if the rule was precisely accurate the required temperature increase would be about 15.8 °C), and in any case the rule is only a rough approximation and cannot always be relied on.
The same is true, up to a point, of the chemical reactions of living things.
They are usually catalyzed by enzymes which change reaction rates, but with no variation in catalytic action, the rule of thumb is still mostly applicable.
In the case of bacteria and fungi, the reactions needed to feed and reproduce speed up at higher temperatures, up to the point that the proteins and other compounds in their cells themselves begin to break down, or denature, so quickly that they cannot be replaced.
This is why high temperatures kill bacteria and other micro-organisms: 'tissue' breakdown reactions reach such rates that they cannot be compensated for and the cell dies.
On the other hand, 'elevated' temperatures short of these result in increased growth and reproduction; if the organism is harmful, perhaps to dangerous levels.
Just as temperature increases speed up reactions, temperature decreases reduce them.
Therefore, to make explosives stable for longer periods, or to keep rubber bands springy, or to force bacteria to slow down their growth, they can be cooled.
That is why shelf life is generally extended by temperature control: (refrigeration, insulated shipping containers, controlled cold chain, etc.)
and why some medicines and foods "must" be refrigerated.
Temperature data loggers and time temperature indicators can record the temperature history of a shipment to help estimate their remaining shelf life. 
In 1951, Penna received an offer to join UNESCO as a specialist in its Regional Office for the Western Hemisphere, of which he became director in 1962.
In Carlos Victor's words, "scholarship and culture represent a precious source of national wealth.
This is why, in every development plan as well as all educational planning, keeping an individual well-informed is an important means of encouraging economic and social development.
In order to be educated and cultured, one needs an efficient system of education, which is hardly conceived without a cultivated and systematic habit of reading.
Reading presupposes the availability of books and consequently a library is needed.
Without libraries, there can be no good primary schools, no efficient secondary schools and no productive universities.
In the absence of libraries, it is neither possible to encourage nor to maintain a permanent education for adults….”