Glossary of chemistry terms
This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws and formulae, laboratory tools and equipment. Chemistry is a physical science concerned with the composition and properties of matter, as well as the changes it undergoes during chemical reactions. Note: All periodic table references refer to the IUPAC Style of the Periodic Table. Absolute zero A theoretical condition concerning a system at the lowest limit of the thermodynamic temperature scale, or zero kelvins, where a system does not emit or absorb energy. By extrapolating the ideal gas law, the internationally accepted value for absolute zero has been determined as −273.15 °C. absorbance abundance accuracy How close a measured value is to the actual or true value. Compare precision. Acid A compound which, when dissolved in water, gives a pH of less than 7.0, or donates a hydrogen ion. acid anhydride A compound with two acyl groups bound to a single oxygen atom. Acid dissociation constant Also called acid ionization acidity constant.
A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is denoted by the symbol Ka. actinides Also called the actinoids. The periodic series of metallic elements with atomic numbers 89 to 103, from actinium through lawrencium. Activated complex A structure that forms because of a collision between molecules while new bonds are formed. Activation energy The minimum energy which must be available to a chemical system with potential reactants in order to result in a chemical reaction. Activity series actual yield acyclic Containing only linear structures of atoms. Addition reaction In organic chemistry, when two or more molecules combine to make a larger one. Adhesion The tendency of dissimilar particles or surfaces to cling to one another as a result of intermolecular forces. Contrast cohesion. Aeration The mixing of air into a liquid or a solid. Alcohol Any organic compound consisting of a hydroxyl functional group attached to a saturated carbon atom.
Aldehyde Any organic compound consisting of a carbonyl group attached to a hydrogen atom and any other R-group. Alkali metal Any of the metallic elements belonging to Group 1 of the periodic table: lithium, potassium, rubidium and francium. Alkaline earth metal Any of the metallic elements belonging to Group 2 of the periodic table: beryllium, calcium, strontium and radium. Alkane Any saturated acyclic hydrocarbon. Alkene An unsaturated hydrocarbon containing at least one pair of double-bonded carbons. Alkyl group A functional group consisting of an alkane missing a hydrogen atom. Alkyne An unsaturated hydrocarbon containing at least one pair of triple-bonded carbons. Allomer A substance that differs in chemical composition but has the same crystalline structure as another substance. Allotrope Elements. Alloy A mixture of metals or of a metal and another element which in combination exhibit a metallic bonding character. Common examples include bronze and pewter. Amalgam amplitude The maximum distance that the particles of the medium carrying the wave move away from their rest position.
Analyte analytical chemistry anion A negatively charged ion. anode 1. An electrode through which the conventional electric current enters into a polarized electrical circuit. 2. The wire or plate of an electrochemical cell having an excess positive charge. Negatively charged anions always move toward the anode. Contrast cathode. Aqueous solution A solution, it is denoted in chemical equations by appending to a chemical formula. Aromaticity A chemical property of conjugated rings of atoms, such as benzene, which results in unusually high stability. Atom A chemical element in its smallest form, made up of protons and neutrons within the nucleus and electrons circling the nucleus. Atomic mass The mass of an atom expressed in unified atomic mass units and nearly equivalent to the mass number. Atomic mass unit See unified atomic mass unit. Atomic number Also called proton number; the number of protons found in the nucleus of an atom of a given chemical element. It is identical to the charge number of the nucleus and is used in the periodic table to uniquely identify each chemical element.
Atomic orbital the region where the electron of the atom may be found atomic radius atomic weight average atomic mass Avogadro's law Avogadro's number The number of particles in one mole of a substance, defined as 6.022×1023 particles. Azeotrope A mixture of liquids whose composition is unchanged by distillation. Barometer A device used to measure atmospheric pressure. Base A substance that accepts a proton and has a pH above 7.0. A common example is sodium hydroxide. Base anhydride Oxides of group I and II metal elements. Beaker Beer–Lambert law biochemistry The study of the chemistry of biological systems and organisms. Bohr model boiling See vaporization. Boiling point The temperature. Boiling-point elevation the process where the boiling point is elevated by adding a substance bond The attraction and repulsion between atoms and molecules, a cornerstone of chemistry. Boyle's law for a given mass of gas at constant temperature, the volume varies inversely with the pressure Bragg's law Brønsted–Lowry acid Any chemical species that dona
American Chemical Society
The American Chemical Society is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS has nearly 157,000 members at all degree levels and in all fields of chemistry, chemical engineering, related fields, it is the world's largest scientific society by membership. The ACS is a 501 non-profit organization and holds a congressional charter under Title 36 of the United States Code, its headquarters are located in Washington, D. C. and it has a large concentration of staff in Ohio. The ACS is a leading source of scientific information through its peer-reviewed scientific journals, national conferences, the Chemical Abstracts Service, its publications division produces 60 scholarly journals including the prestigious Journal of the American Chemical Society, as well as the weekly trade magazine Chemical & Engineering News. The ACS holds national meetings twice a year covering the complete field of chemistry and holds smaller conferences concentrating on specific chemical fields or geographic regions.
The primary source of income of the ACS is the Chemical Abstracts Service, a provider of chemical databases worldwide. The organization publishes textbooks, administers several national chemistry awards, provides grants for scientific research, supports various educational and outreach activities. In 1874, a group of American chemists gathered at the Joseph Priestley House to mark the 100th anniversary of Priestley's discovery of oxygen. Although there was an American scientific society at that time, the growth of chemistry in the U. S. prompted those assembled to consider founding a new society that would focus more directly on theoretical and applied chemistry. Two years on April 6, 1876, during a meeting of chemists at the University of the City of New York the American Chemical Society was founded; the society received its charter of incorporation from the State of New York in 1877. Charles F. Chandler, a professor of chemistry at Columbia University, instrumental in organizing the society said that such a body would “prove a powerful and healthy stimulus to original research, … would awaken and develop much talent now wasting in isolation, … members of the association into closer union, ensure a better appreciation of our science and its students on the part of the general public.”Although Chandler was a choice to become the society's first president because of his role in organizing the society, New York University chemistry professor John William Draper was elected as the first president of the society because of his national reputation.
Draper was a photochemist and pioneering photographer who had produced one of the first photographic portraits in 1840. Chandler would serve as president in 1881 and 1889. In the ACS logo designed in the early 20th century by Tiffany's Jewelers and used since 1909, a stylized symbol of a kaliapparat is used; the Journal of the American Chemical Society was founded in 1879 to publish original chemical research. It was the first journal published by ACS and is still the society's flagship peer-reviewed publication. In 1907, Chemical Abstracts was established as a separate journal, which became the Chemical Abstracts Service, a division of ACS that provides chemical information to researchers and others worldwide. Chemical & Engineering News is a weekly trade magazine, published by ACS since 1923; the society adopted a new constitution aimed at nationalizing the organization in 1890. In 1905, the American Chemical Society moved from New York City to Washington, D. C. ACS was reincorporated under a congressional charter in 1937.
It was granted by the U. S. Congress and signed by president Franklin D. Roosevelt. ACS's headquarters moved to its current location in downtown Washington in 1941. Notable Presidents of the American Chemical Society ACS first established technical divisions in 1908 to foster the exchange of information among scientists who work in particular fields of chemistry or professional interests. Divisional activities include organizing technical sessions at ACS meetings, publishing books and resources, administering awards and lectureships, conducting other events; the original five divisions were 1) organic chemistry, 2) industrial chemists and chemical engineers, 3) agricultural and food chemistry, 4) fertilizer chemistry, 5) physical and inorganic chemistry. As of 2016, there are 32 technical divisions of ACS; this is the largest division of the Society. It marked its 100th Anniversary in 2008; the first Chair of the Division was Edward Curtis Franklin. The Organic Division played a part in establishing Organic Syntheses, Inc. and Organic Reactions, Inc. and it maintains close ties to both organizations.
The Division's best known activities include organizing symposia at the biannual ACS National Meetings, for the purpose of recognizing promising Assistant Professors, talented young researchers, outstanding technical contributions from junior-level chemists, in the field of organic chemistry. The symposia honor national award winners, including the Arthur C. Cope Award, Cope Scholar Award, James Flack Norris Award in Physical Organic Chemistry, Herbert C. Brown Award for Creative Research in Synthetic Methods; the Division helps to organize symposia at the international meeting called Pacifichem, it organizes the biennial National Organic Chemistry Symposium which highlights recent advances in organic chemistry and hosts the Roger Adams Award address. The Division organizes corporate sponsorships to provide fellowships for Ph. D. stu
In chemical engineering and related fields, a unit operation is a basic step in a process. Unit operations involve a physical change or chemical transformation such as separation, evaporation, polymerization and other reactions. For example, in milk processing, homogenization and packaging are each unit operations which are connected to create the overall process. A process may require many unit operations to obtain the desired product from the starting materials, or feedstocks; the different chemical industries were regarded as different industrial processes and with different principles. Arthur Dehon Little propounded the concept of "unit operations" to explain industrial chemistry processes in 1916. In 1923, William H. Walker, Warren K. Lewis and William H. McAdams wrote the book The Principles of Chemical Engineering and explained that the variety of chemical industries have processes which follow the same physical laws, they summed up these similar processes into unit operations. Each unit operation follows the same physical laws and may be used in all relevant chemical industries.
For instance, the same engineering is required to design a mixer for either napalm or porridge if the use, market or manufacturers are different. The unit operations form the fundamental principles of chemical engineering. Chemical engineering unit operations consist of five classes: Fluid flow processes, including fluids transportation and solids fluidization. Heat transfer processes, including heat exchange. Mass transfer processes, including gas absorption, extraction and drying. Thermodynamic processes, including gas liquefaction, refrigeration. Mechanical processes, including solids transportation and pulverization, screening and sieving. Chemical engineering unit operations fall in the following categories which involve elements from more than one class: Combination Separation Reaction Furthermore, there are some unit operations which combine these categories, such as reactive distillation and stirred tank reactors. A "pure" unit operation is a physical transport process, while a mixed chemical/physical process requires modeling both the physical transport, such as diffusion, the chemical reaction.
This is necessary for designing catalytic reactions, is considered a separate discipline, termed chemical reaction engineering. Chemical engineering unit operations and chemical engineering unit processing form the main principles of all kinds of chemical industries and are the foundation of designs of chemical plants and equipment used. In general, unit operations are designed by writing down the balances for the transported quantity for each elementary component in the form of equations, solving the equations for the design parameters selecting an optimal solution out of the several possible and designing the physical equipment. For instance, distillation in a plate column is analyzed by writing down the mass balances for each plate, wherein the known vapor-liquid equilibrium and efficiency, drip out and drip in comprise the total mass flows, with a sub-flow for each component. Combining a stack of these gives the system of equations for the whole column. There is a range of solutions, because a higher reflux ratio enables fewer plates, vice versa.
The engineer must find the optimal solution with respect to acceptable volume holdup, column height and cost of construction. Distillation Design Extrusion Process simulation Separation process Unit Operations of Chemical Engineering Unit process Media related to Unit operations at Wikimedia Commons
The chemical industry comprises the companies that produce industrial chemicals. Central to the modern world economy, it converts raw materials into more than 70,000 different products; the plastics industry contains some overlap, as most chemical companies produce plastic as well as other chemicals. Various professionals are involved in the chemical industry including chemical engineers, lab chemists, etc; as of 2018, the chemical industry comprises 15% of the US manufacturing economic sector. Although chemicals were made and used throughout history, the birth of the heavy chemical industry coincided with the beginnings of the Industrial Revolution in general. One of the first chemicals to be produced in large amounts through industrial processes was sulfuric acid. In 1736, the pharmacist Joshua Ward developed a process for its production that involved heating saltpeter, allowing the sulfur to oxidize and combine with water, it was the first practical production of sulphuric acid on a large scale.
John Roebuck and Samuel Garbett were the first to establish a large-scale factory in Prestonpans, Scotland, in 1749, which used leaden condensing chambers for the manufacture of sulfuric acid. In the early 18th century, cloth was bleached by treating it with stale urine or sour milk and exposing it to sunlight for long periods of time, which created a severe bottleneck in production. Sulfuric acid began to be used as a more efficient agent as well as lime by the middle of the century, but it was the discovery of bleaching powder by Charles Tennant that spurred the creation of the first great chemical industrial enterprise, his powder was made by reacting chlorine with dry slaked lime and proved to be a cheap and successful product. He opened a factory in St Rollox, north of Glasgow, production went from just 52 tons in 1799 to 10,000 tons just five years later. Soda ash was used since ancient times in the production of glass, textile and paper, the source of the potash had traditionally been wood ashes in Western Europe.
By the 18th century, this source was becoming uneconomical due to deforestation, the French Academy of Sciences offered a prize of 2400 livres for a method to produce alkali from sea salt. The Leblanc process was patented in 1791 by Nicolas Leblanc who built a Leblanc plant at Saint-Denis, he was denied his prize money because of the French Revolution. However, it was in Britain that the Leblanc process took off. William Losh built the first soda works in Britain at the Losh and Bell works on the River Tyne in 1816, but it remained on a small scale due to large tariffs on salt production until 1824; when these tariffs were repealed, the British soda industry was able to expand. James Muspratt's chemical works in Liverpool and Charles Tennant's complex near Glasgow became the largest chemical production centres anywhere. By the 1870s, the British soda output of 200,000 tons annually exceeded that of all other nations in the world combined; these huge factories began to produce a greater diversity of chemicals as the Industrial Revolution matured.
Large quantities of alkaline waste were vented into the environment from the production of soda, provoking one of the first pieces of environmental legislation to be passed in 1863. This provided for close inspection of the factories and imposed heavy fines on those exceeding the limits on pollution. Methods were soon devised to make useful byproducts from the alkali; the Solvay process was developed by the Belgian industrial chemist Ernest Solvay in 1861. In 1864, Solvay and his brother Alfred constructed a plant in the Belgian town of Charleroi and in 1874, they expanded into a larger plant in Nancy, France; the new process proved more economical and less polluting than the Leblanc method, its use spread. In the same year, Ludwig Mond visited Solvay to acquire the rights to use his process, he and John Brunner formed the firm of Brunner, Mond & Co. and built a Solvay plant at Winnington, England. Mond was instrumental in making the Solvay process a commercial success; the late 19th century saw an explosion in both the quantity of production and the variety of chemicals that were manufactured.
Large chemical industries took shape in Germany and in the United States. Production of artificial manufactured fertilizer for agriculture was pioneered by Sir John Lawes at his purpose-built Rothamsted Research facility. In the 1840s he established large works near London for the manufacture of superphosphate of lime. Processes for the vulcanization of rubber were patented by Charles Goodyear in the United States and Thomas Hancock in England in the 1840s; the first synthetic dye was discovered by William Henry Perkin in London. He transformed aniline into a crude mixture which, when extracted with alcohol, produced a substance with an intense purple colour, he developed the first synthetic perfumes. However, it was German industry that began to dominate the field of synthetic dyes; the three major firms BASF, Bayer and Hoechst produced several hundred different dyes, by 1913, the German industry produced 90 percent of the world supply of dyestuffs and sold about 80 percent of their production abroad.
In the United States, Herbert Henry Dow's use of electrochemistry to produce chemicals from brine was a commercial success that helped to promote the country's chemical industry. The petrochemical industry can be traced back to the oil works of James Young in Scotland and Abraham Pineo Gesne
Institution of Chemical Engineers
The Institution of Chemical Engineers is a global professional engineering institution with over 40,000 members in over 120 countries worldwide. It was founded in 1922 and awarded a Royal Charter in 1957, it has offices in Rugby, Melbourne, New Zealand, Kuala Lumpur, Singapore. The IChemE is licensed by the Engineering Council UK to assess candidates for inclusion on ECUK's Register of professional Engineers, giving the status of Chartered Engineer, Incorporated Engineer and Engineering Technician, it is licensed by the Science Council to grant the status of Chartered Scientist and Registered Science Technician. It is licensed by the Society for the Environment to grant the status of Chartered Environmentalist, it is a member of the European Federation of Chemical Engineering. It accredits chemical engineering degree courses in 25 countries worldwide; the mission of this organisation is to build and support a community and network of professionals involved in all facets of the Chemical Engineering discipline.
IChemE has two main types of membership and non-qualified, with the technician member grade being available in both categories. Qualified membership grades. Fellow - A chemical engineering professional in a senior position in industry and/or academia. Entitling the holder to the post-nominal FIChemE and is a chartered grade encompassing all the privileges of Chartered Member grade. Chartered Member - Internationally recognised level of professional and academic competence requiring at least 4 years of field experience and a bachelors degree with honours. Entitles the holder to the post-nominal MIChemE and registration as one or a combination of; this entitles the individual to register as a European Engineer with the pre-nominal Eur Ing. Associate Member - This grade is for young professionals who are qualified in chemical & process engineering to bachelors with honours level or a higher; this is the grade held by those working towards Chartered Member level or those graduates working other fields.
This grade entitles the holder to the post-nominal AMIChemE. This grade can lead to the grade of Incorporated Engineer for those with some field experience but which falls short of the level required for Chartered Member grade. Technician Member - Uses practical understanding to solve engineering problems and could have a qualification, an apprenticeship or years of experience; this grade can lead to the Eng Tech TIChemE post-nominal and now in conjunction with the Nuclear Institute the post-nominal Eng Tech TIChemE TNucI. Non-qualified membership grades. Associate Fellow - Senior professionals trained in other fields of a level comparable to Fellow in other professional bodies. Affiliate - For people working in, with or with a general interest in the sector. Student - For undergraduate chemical & process engineering students; the IChemE Innovation and Excellence Awards take place in November in the UK. The awards are regarded throughout the process industries for recognising and rewarding chemical engineering excellence and innovation.
There are 14 categories in total. The organisation is working on newer award programs in other countries and in 2012 events took place in Singapore and North America; the Ashok Kumar Fellowship is an opportunity for a graduate to spend three months working at the UK Parliamentary Office for Science and Technology. The first fellowship was completed in 2012 by James Lawrence, a PhD student at University College, London; the fellowship is jointly funded by the IChemE and the Northeast of England Process Industry Cluster. The Fellowship was set up in memory of Ashok Kumar, the only serving chemical engineer in the Parliament of the United Kingdom at the time of his sudden death in 2010. Kumar was an IChemE Fellow, the Labour MP for Middlesbrough South and Cleveland East since 1997, his second time in parliament following a brief stint in 1991. IChemE established an educational program whynotchemeng? in 2001 to help young people find out more about a career in the field of chemical engineering. In addition to careers information for students, whynotchemeng? provides schools with free teaching resources for Key Stages 4&5 including Top Ten Flash Bang Demos, a citizenship lesson and dilution plant challenge, plus free careers literature including posters and careers packs.
The coat of arms is a shield with two figures. On the left a helmeted woman, Pallas Athene, the goddess of wisdom, on the right, a bearded man with a large hammer, Hephaestus the god of technology and of fire; the shield itself shows a salamander as the symbol of chemistry, a corn grinding mill as a symbol of continuous processes. Between these is a diagonal stripe in red and blue in steps to indicate the cascade nature of many chemical engineering processes; the shield is surmounted by helmet on, a dolphin, in heraldry associated with intellectual activity, represents the importance of fluid mechanics. Just below the dolphin are two Integral signs to illustrate the necessity of mathematics and in particular calculus; the Latin motto is "Findendo Fingere Disco" or "I learn to make by separating". Chemical Engineering Research and Design Process Safety and Environmental Protection Food and Bioproducts Processing Education for Chemical Engineers The Chemical Engineer Loss Prevention Bulletin Conference Proceedings Technical Guides Safety Books Forms of Contract Roland Clift Developer of Life cycle assessment and broadcaster on en
Industrial control system
Industrial control system is a general term that encompasses several types of control systems and associated instrumentation used for industrial process control. Such systems can range from a few modular panel-mounted controllers to large interconnected and interactive distributed control systems with many thousands of field connections. All systems receive data received from remote sensors measuring process variables, compare these with desired set points and derive command functions which are used to control a process through the final control elements, such as control valves; the larger systems are implemented by Supervisory Control and Data Acquisition systems, or distributed control systems, programmable logic controllers, though SCADA and PLC systems are scalable down to small systems with few control loops. Such systems are extensively used in industries such as chemical processing and paper manufacture, power generation and gas processing and telecommunications; the simplest control systems are based around small discrete controllers with a single control loop each.
These are panel mounted which allows direct viewing of the front panel and provides means of manual intervention by the operator, either to manually control the process or to change control setpoints. These would be pneumatic controllers, a few of which are still in use, but nearly all are now electronic. Quite complex systems can be created with networks of these controllers communicating using industry standard protocols. Networking allow the use of local or remote SCADA operator interfaces, enables the cascading and interlocking of controllers. However, as the number of control loops increase for a system design there is a point where the use of a programmable logic controller or distributed control system is more manageable or cost-effective. A distributed control system is a digital processor control system for a process or plant, wherein controller functions and field connection modules are distributed throughout the system; as the number of control loops grows, DCS becomes more cost effective than discrete controllers.
Additionally a DCS provides supervisory management over large industrial processes. In a DCS, a hierarchy of controllers is connected by communication networks, allowing centralised control rooms and local on-plant monitoring and control. A DCS enables easy configuration of plant controls such as cascaded loops and interlocks, easy interfacing with other computer systems such as production control, it enables more sophisticated alarm handling, introduces automatic event logging, removes the need for physical records such as chart recorders and allows the control equipment to be networked and thereby located locally to equipment being controlled to reduce cabling. A DCS uses custom-designed processors as controllers, uses either proprietary interconnections or standard protocols for communication. Input and output modules form the peripheral components of the system; the processors receive information from input modules, process the information and decide control actions to be performed by the output modules.
The input modules receive information from sensing instruments in the process and the output modules transmit instructions to the final control elements, such as control valves. The field inputs and outputs can either be continuously changing analog signals e.g. current loop or 2 state signals that switch either on or off, such as relay contacts or a semiconductor switch. Distributed control systems can also support Foundation Fieldbus, PROFIBUS, HART, Modbus and other digital communication buses that carry not only input and output signals but advanced messages such as error diagnostics and status signals. Supervisory control and data acquisition is a control system architecture that uses computers, networked data communications and graphical user interfaces for high-level process supervisory management; the operator interfaces which enable monitoring and the issuing of process commands, such as controller set point changes, are handled through the SCADA supervisory computer system. However, the real-time control logic or controller calculations are performed by networked modules which connect to other peripheral devices such as programmable logic controllers and discrete PID controllers which interface to the process plant or machinery.
The SCADA concept was developed as a universal means of remote access to a variety of local control modules, which could be from different manufacturers allowing access through standard automation protocols. In practice, large SCADA systems have grown to become similar to distributed control systems in function, but using multiple means of interfacing with the plant, they can control large-scale processes that can include multiple sites, work over large distances. This is a commonly-used architecture industrial control systems, however there are concerns about SCADA systems being vulnerable to cyberwarfare or cyberterrorism attacks; the SCADA software operates on a supervisory level as control actions are performed automatically by RTUs or PLCs. SCADA control functions are restricted to basic overriding or supervisory level intervention. A feedback control loop is directly controlled by the RTU or PLC, but the SCADA software monitors the overall performance of the loop. For example, a PLC may control the flow of cooling water through part of an industrial process to a set point level, but the SCADA system software will allow operators to change the set points for the flow.
The SCADA enables alarm conditions, such as loss of flow or high temperature, to be displayed and recorded. PLCs can range from small modular devices with tens of inputs and outputs in a
Chemical engineering is a branch of engineering that uses principles of chemistry, mathematics and economics to efficiently use, produce and transport chemicals and energy. A chemical engineer designs large-scale processes that convert chemicals, raw materials, living cells and energy into useful forms and products. Chemical engineers are involved in many aspects of plant design and operation, including safety and hazard assessments, process design and analysis, control engineering, chemical reaction engineering, biological engineering, construction specification, operating instructions. Chemical engineering degree is directly linked with all the majors of various engineering disciplines. A 1996 British Journal for the History of Science article cites James F. Donnelly for mentioning an 1839 reference to chemical engineering in relation to the production of sulfuric acid. In the same paper however, George E. Davis, an English consultant, was credited for having coined the term. Davis tried to found a Society of Chemical Engineering, but instead it was named the Society of Chemical Industry, with Davis as its first Secretary.
The History of Science in United States: An Encyclopedia puts the use of the term around 1890. "Chemical engineering", describing the use of mechanical equipment in the chemical industry, became common vocabulary in England after 1850. By 1910, the profession, "chemical engineer," was in common use in Britain and the United States. Chemical engineering emerged upon the development of unit operations, a fundamental concept of the discipline of chemical engineering. Most authors agree that Davis invented the concept of unit operations if not developed it, he gave a series of lectures on unit operations at the Manchester Technical School in 1887, considered to be one of the earliest such about chemical engineering. Three years before Davis' lectures, Henry Edward Armstrong taught a degree course in chemical engineering at the City and Guilds of London Institute. Armstrong's course failed because its graduates were not attractive to employers. Employers of the time would have rather hired mechanical engineers.
Courses in chemical engineering offered by Massachusetts Institute of Technology in the United States, Owens College in Manchester and University College London suffered under similar circumstances. Starting from 1888, Lewis M. Norton taught at MIT the first chemical engineering course in the United States. Norton's course was contemporaneous and similar to Armstrong's course. Both courses, however merged chemistry and engineering subjects along with product design. "Its practitioners had difficulty convincing engineers that they were engineers and chemists that they were not chemists." Unit operations was introduced into the course by William Hultz Walker in 1905. By the early 1920s, unit operations became an important aspect of chemical engineering at MIT and other US universities, as well as at Imperial College London; the American Institute of Chemical Engineers, established in 1908, played a key role in making chemical engineering considered an independent science, unit operations central to chemical engineering.
For instance, it defined chemical engineering to be a "science of itself, the basis of which is... unit operations" in a 1922 report. Meanwhile, promoting chemical engineering as a distinct science in Britain led to the establishment of the Institution of Chemical Engineers in 1922. IChemE helped make unit operations considered essential to the discipline. In 1940s, it became clear that unit operations alone were insufficient in developing chemical reactors. While the predominance of unit operations in chemical engineering courses in Britain and the United States continued until the 1960s, transport phenomena started to experience greater focus. Along with other novel concepts, such as process systems engineering, a "second paradigm" was defined. Transport phenomena gave an analytical approach to chemical engineering while PSE focused on its synthetic elements, such as control system and process design. Developments in chemical engineering before and after World War II were incited by the petrochemical industry, advances in other fields were made as well.
Advancements in biochemical engineering in the 1940s, for example, found application in the pharmaceutical industry, allowed for the mass production of various antibiotics, including penicillin and streptomycin. Meanwhile, progress in polymer science in the 1950s paved way for the "age of plastics". Concerns regarding the safety and environmental impact of large-scale chemical manufacturing facilities were raised during this period. Silent Spring, published in 1962, alerted its readers to the harmful effects of DDT, a potent insecticide; the 1974 Flixborough disaster in the United Kingdom resulted in 28 deaths, as well as damage to a chemical plant and three nearby villages. The 1984 Bhopal disaster in India resulted in 4,000 deaths; these incidents, along with other incidents, affected the reputation of the trade as industrial safety and environmental protection were given more focus. In response, the IChemE required safety to be part of every degree course that it accredited after 1982. By the 1970s, legislation and monitoring agencies were instituted in various countries, such as France and the United States.
Advancements in computer science found applications designing and managing plants, simplifying calculations and drawings that had to be done manually. The c