What is the relationship between dynamite and Nobel Prizes?

Alfred Nobel was a Swedish chemist and engineer whose family owned an explosives factory. When Alfred's brother died from an explosion at the plant, the chemist became obsessed with finding a way to make explosives safer to handle.

Nitroglycerin was a general-purpose explosive then, but it is so unstable that it can explode when simply shaken. Nobel found that nitroglycerin can be much more stable - and safely handled - if it was soaked inside, or mixed with certain absorbent substances such as wood pulp or sawdust.

In 1867, he was granted a patent for his new explosive, which he called dynamite, from the Greek word meaning "potency.

When the Swedish chemist died in 1896, he provided in his will that his fortune should be used to establish five annual prizes in the achievements of medicine, physics, chemistry, literature and peace. These awards, called Nobel Prizes, are still presented each year. A sixth distinction, in economics, was added in 1969.

.

How does a nuclear reactor generate electricity?

A handful of uranium provides as much electricity as 70 tons of coal or 30 barrels of oil. A nuclear reactor to power a city of one million people consumes only 3 kg of uranium per day, making it the most concentrated energy source used by man.

Uranium is one of the densest natural elements and its atoms are very unstable. The nucleus of the atom only needs a small "push" to disintegrate, and when this happens it releases large amounts of energy, in the so-called nuclear fission.

This "push" can be received from neutrons, particles much smaller than atoms, which collide with the nucleus and disintegrate it. During this process at least two more neutrons are produced, which detach from the atom and then cause other fissures, so that these can continue indefinitely.

The energy of fission can be released little by little, and used to heat water. The water vapour is used to activate an electricity generator.

This is how a nuclear reactor works.

.

How is seawater desalinated?

The world faces a growing demand for water. In areas of scarce rainfall, such as the Near East, the natural water supply is insufficient. One answer is to desalinate seawater.

From the 4th century B.C. a method was known for this, when Aristotle discovered that by boiling seawater, the steam was free of salt.

The simplest desalination plant is a still where water is boiled and steam is condensed. A solar still can be improvised by placing a glass dome over a saltwater pond. The water is heated, then evaporated, condensed into the glass and finally drained into collection channels. A still of just under 1m² can produce 4-5 litres of drinking water per day.

A much larger alembic is required to desalinate usable quantities of water. The water is first heated above its boiling point in a pressure chamber so that it does not boil. It then flows into a lower pressure chamber, where part of the water is instantly converted to steam. The water that did not boil in the first chamber passes into the second, slightly lower pressure chamber, where it partially evaporates and condenses.

A modern desalination method, called reverse osmosis, is more profitable than the one described. It consists of using plastic membranes with tiny perforations, which allow water molecules to pass but not salt molecules. The membranes are placed in tubes, and the salt water is passed through them, pumping it under pressure. The desalinated water then drips out of the tube.

.

What is fire made of?

 Fire is a chemical reaction resulting from the combination of a fuel with atmospheric oxygen. Once initiated, this reaction is self-sustaining, generates high temperatures and produces heat, light, gases and particulate matter.

The visible region of the flame is where this chemical process takes place, i.e. fire is essentially a phase of the gaseous phenomenon: For combustion to take place, solid and liquid fuels must become gases.

By boiling a liquid, this transformation is achieved; the solids reach it through a process called pyrolysis, which generates volatile gases.

The flame itself is a plasma of very hot atoms that emit energy in the form of light while its electrons, which have reached higher energy levels by absolving heat, fall into lower energy states.

.