Thermodynamics

-

Thermodynamics, field of physics that describes and correlates the physical properties of macroscopic systems of matter and energy. The principles of thermodynamics are of fundamental importance to all branches of science and engineering.

A central concept of thermodynamics is that of the macroscopic system, defined as a geometrically isolable piece of matter in coexistence with an infinite, unperturbable environment. The state of a macroscopic system in equilibrium can be described in terms of such measurable properties as temperature, pressure, and volume, which are known as thermodynamic variables. Many other variables (such as density, specific heat, compressibility, and the coefficient of thermal expansion) can be identified and correlated, to produce a more complete description of an object and its relationship to its environment.

When a macroscopic system moves from one state of equilibrium to another, a thermodynamic process is said to take place. Some processes are reversible and others are irreversible. The laws of thermodynamics, discovered in the 19th century through painstaking experimentation, govern the nature of all thermodynamic processes and place limits on them.

Topics:

Comments

Post a Comment

Popular posts from this blog

Berzelius, Jöns Jakob, Baron

-
Berzelius, Jöns Jakob, Baron (1779-1848), Swedish chemist, considered one of the founders of modern chemistry . Berzelius was born near Linköping. While studying medicine at the University of Uppsala, he became interested in chemistry. After practicing medicine and lecturing, he became a professor of botany and pharmacy at Stockholm in 1807. From 1815 to 1832 he was professor of chemistry at the Caroline Medico-Chirurgical Institute in Stockholm. He became a member of the Stockholm Academy of Sciences in 1808 and in 1818 became its permanent secretary. For his contributions to science, Berzelius was made a baron in 1835 by Charles XIV John, king of Sweden and Norway. Berzelius's research extended into every branch of chemistry and was extraordinary for its scope and accuracy. He discovered three chemical elements— cerium , selenium , and thorium —and was the first to isolate silicon , zirconium , and titanium . He introduced the term catalyst into chemistry and was the first to ela
Read more

Hanaoka Seishu

-
Image
A stamp depicting the image of Hanaoka Seishu. Hanaoka Seishu (1760-1835), Japanese physician and pioneer of anesthetic surgery. Hanaoka studied traditional Sino-Japanese medicine, as well as what was then known about Western surgery in Japan. For over two decades he experimented with various drugs. Ultimately he created mafutsusan, an anesthetic compound made from six traditional plant-based drugs, including the alkaloids aconite (from the monkshood plant) and datura (from jimsonweed ). In 1805, using mafutsusan as an anesthetic, Hanaoka removed a tumor during breast cancer surgery. This was the world's first recorded successful surgical operation with anesthesia. Later, Hanaoka used the drug for other surgical operations, developing techniques for bladder stone removal and for amputation. Hanaoka attracted many students, and his surgical techniques became known as the Hanaoka method.
Read more

Mendel’s Laws

-
Mendel’s Laws, principles of hereditary transmission of physical characteristics. They were formulated in 1865 by the Augustinian monk Gregor Johann Mendel . Experimenting with seven contrasting characteristics of pure-breeding garden peas, Mendel discovered that by crossing tall and dwarf parents, for example, he got hybrid offspring that resembled the tall parent rather than being a medium-height blend. To explain this he conceived of hereditary units, now called genes, which often expressed dominant or recessive characteristics. Formulating his first principle (the law of segregation), Mendel stated that genes normally occur in pairs in the ordinary body cells, but segregate in the formation of sex cells (eggs or sperm), each member of the pair becoming part of the separate sex cell. When egg and sperm unite, forming a gene pair, the dominant gene (tallness) masks the recessive gene (shortness). To corroborate the existence of such hereditary units, Mendel went on to interbreed the
Read more