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95-457: This process was patented in 1831 by British vinegar merchant Peregrine Phillips. In addition to being a far more economical process for producing concentrated sulfuric acid than the previous lead chamber process , the contact process also produces sulfur trioxide and oleum . In 1901 Eugen de Haën patented the basic process involving combining sulfur dioxide and oxygen in the presence of vanadium oxides , producing sulfur trioxide which

190-434: A hydrogen-based economy . It is an alternative to electrolysis , and does not require hydrocarbons like current methods of steam reforming . But note that all of the available energy in the hydrogen so produced is supplied by the heat used to make it. Sulfuric acid is rarely encountered naturally on Earth in anhydrous form, due to its great affinity for water . Dilute sulfuric acid is a constituent of acid rain , which

285-610: A base and can be protonated, forming the [H 3 SO 4 ] ion. Salts of [H 3 SO 4 ] have been prepared (e.g. trihydroxyoxosulfonium hexafluoroantimonate(V) [H 3 SO 4 ] [SbF 6 ] ) using the following reaction in liquid HF : The above reaction is thermodynamically favored due to the high bond enthalpy of the Si–F bond in the side product. Protonation using simply fluoroantimonic acid , however, has met with failure, as pure sulfuric acid undergoes self-ionization to give [H 3 O] ions: which prevents

380-408: A burnt appearance in which the carbon appears much like soot that results from fire. Although less dramatic, the action of the acid on cotton , even in diluted form, destroys the fabric. The reaction with copper(II) sulfate can also demonstrate the dehydration property of sulfuric acid. The blue crystals change into white powder as water is removed. Sulfuric acid reacts with most bases to give

475-686: A consonant followed by an unstressed -re (pronounced /ə(r)/ ). In modern American English, most of these words have the ending -er . The difference is most common for words ending in -bre or -tre : British spellings calibre , centre , fibre , goitre , litre , lustre , manoeuvre , meagre , metre (length) , mitre , nitre , ochre , reconnoitre , sabre , saltpetre , sepulchre , sombre , spectre , theatre (see exceptions ) and titre all have -er in American spelling. In Britain, both -re and -er spellings were common before Johnson's 1755 dictionary

570-411: A dehydrating agent, forming the nitronium ion NO + 2 , which is important in nitration reactions involving electrophilic aromatic substitution . This type of reaction, where protonation occurs on an oxygen atom, is important in many organic chemistry reactions, such as Fischer esterification and dehydration of alcohols. When allowed to react with superacids , sulfuric acid can act as

665-468: A distinctive set of Canadian English spellings is viewed by many Canadians as one of the unique aspects of Canadian culture (especially when compared to the United States). In Australia, -or endings enjoyed some use throughout the 19th century and in the early 20th century. Like Canada, though, most major Australian newspapers have switched from " -or " endings to " -our " endings. The " -our " spelling

760-490: A emium , and a enigma . In others, it is kept in all varieties: for example, phoenix , and usually subpoena , but Phenix in Virginia . This is especially true of names: Aegean (the sea), Caesar , Oedipus , Phoebe , etc., although "caesarean section" may be spelled as "cesarean section". There is no reduction of Latin -ae plurals (e.g., larv ae ); nor where the digraph <ae>/<oe> does not result from

855-458: A eon , an a emia , an a esthesia , c a ecum , c a esium , c o eliac , diarrh o ea , encyclop a edia , f a eces , f o etal , gyn a ecology , h a emoglobin , h a emophilia , leuk a emia , o esophagus , o estrogen , orthop a edic , pal a eontology , p a ediatric , p a edophile . Oenology is acceptable in American English but is deemed

950-527: A minor variant of enology , whereas although archeology and ameba exist in American English, the British versions amoeba and archaeology are more common. The chemical haem (named as a shortening of h a emoglobin ) is spelled heme in American English, to avoid confusion with hem . Canadian English mostly follows American English in this respect, although it is split on gynecology (e.g. Society of Obstetricians and Gynaecologists of Canada vs.

1045-554: A mistaken etymology. The etymologically correct original spelling fetus reflects the Latin original and is the standard spelling in medical journals worldwide; the Oxford English Dictionary notes that "In Latin manuscripts both fētus and foetus are used". The Ancient Greek diphthongs <αι> and <οι> were transliterated into Latin as <ae> and <oe>. The ligatures æ and œ were introduced when

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1140-524: A result, modern English orthography varies only minimally between countries and is far from phonemic in any country. In the early 18th century, English spelling was inconsistent. These differences became noticeable after the publication of influential dictionaries . Today's British English spellings mostly follow Johnson's A Dictionary of the English Language (1755), while many American English spellings follow Webster's An American Dictionary of

1235-487: A slower rate, so that the acid neutralizing capacity (ANC) of the aquifer can neutralize the produced acid. In such cases, the total dissolved solids (TDS) concentration of the water can be increased from the dissolution of minerals from the acid-neutralization reaction with the minerals. Sulfuric acid is used as a defense by certain marine species, for example, the phaeophyte alga Desmarestia munda (order Desmarestiales ) concentrates sulfuric acid in cell vacuoles. In

1330-660: A suffix for agentive ( reader , user , winner ) and comparative ( louder , nicer ) forms. One outcome is the British distinction of meter for a measuring instrument from metre for the unit of length. However, while " poetic metre " is often spelled as -re , pentameter , hexameter , etc. are always -er . Many other words have -er in British English. These include Germanic words, such as anger , mother , timber and water , and such Romance-derived words as danger , quarter and river . The ending -cre , as in acre , lucre , massacre , and mediocre ,

1425-413: A temperature will lower the formation rate to an uneconomical level. Hence to increase the reaction rate, high temperatures (450 °C), medium pressures (1-2  atm ), and vanadium(V) oxide (V 2 O 5 ) are used to ensure an adequate (>95%) conversion. The catalyst only serves to increase the rate of reaction as it does not change the position of the thermodynamic equilibrium . The mechanism for

1520-508: A time before spelling standards were developed. For instance, some spellings seen as "American" today were once commonly used in Britain, and some spellings seen as "British" were once commonly used in the United States. A "British standard" began to emerge following the 1755 publication of Samuel Johnson 's A Dictionary of the English Language , and an "American standard" started following

1615-510: A vapor pressure of <1 mmHg at 40 °C. In the solid state, sulfuric acid is a molecular solid that forms monoclinic crystals with nearly trigonal lattice parameters. The structure consists of layers parallel to the (010) plane, in which each molecule is connected by hydrogen bonds to two others. Hydrates H 2 SO 4 · n H 2 O are known for n = 1, 2, 3, 4, 6.5, and 8, although most intermediate hydrates are stable against disproportionation . Anhydrous H 2 SO 4

1710-432: Is - /s/ for the noun and - /z/ for the verb). For licence / license or practice / practise , British English also keeps the noun–verb distinction graphically (although phonetically the two words in each pair are homophones with - /s/ pronunciation). On the other hand, American English uses license and practice for both nouns and verbs (with - /s/ pronunciation in both cases too). American English has kept

1805-420: Is a colorless, odorless, and viscous liquid that is soluble with water. Pure sulfuric acid does not occur naturally due to its strong affinity to water vapor ; it is hygroscopic and readily absorbs water vapor from the air . Concentrated sulfuric acid is a strong oxidant with powerful dehydrating properties, making it highly corrosive towards other materials, from rocks to metals. Phosphorus pentoxide

1900-442: Is a common laboratory demonstration. The sugar darkens as carbon is formed, and a rigid column of black, porous carbon called a carbon snake may emerge. Similarly, mixing starch into concentrated sulfuric acid gives elemental carbon and water. The effect of this can also be seen when concentrated sulfuric acid is spilled on paper. Paper is composed of cellulose , a polysaccharide related to starch. The cellulose reacts to give

1995-556: Is a notable exception in that it is not dehydrated by sulfuric acid but, to the contrary, dehydrates sulfuric acid to sulfur trioxide . Upon addition of sulfuric acid to water, a considerable amount of heat is released; thus, the reverse procedure of adding water to the acid is generally avoided since the heat released may boil the solution, spraying droplets of hot acid during the process. Upon contact with body tissue, sulfuric acid can cause severe acidic chemical burns and secondary thermal burns due to dehydration. Dilute sulfuric acid

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2090-484: Is a strong acid: The product of this ionization is HSO − 4 , the bisulfate anion. Bisulfate is a far weaker acid: The product of this second dissociation is SO 2− 4 , the sulfate anion. Concentrated sulfuric acid has a powerful dehydrating property, removing water ( H 2 O ) from other chemical compounds such as table sugar ( sucrose ) and other carbohydrates , to produce carbon , steam , and heat. Dehydration of table sugar (sucrose)

2185-429: Is a very polar liquid, having a dielectric constant of around 100. It has a high electrical conductivity , a consequence of autoprotolysis , i.e. self- protonation  : The equilibrium constant for autoprotolysis (25 °C) is: The corresponding equilibrium constant for water , K w is 10 , a factor of 10 (10 billion) smaller. In spite of the viscosity of the acid, the effective conductivities of

2280-675: Is almost identical to British spelling, except in the word fiord (instead of fjord ) . There is an increasing use of macrons in words that originated in Māori and an unambiguous preference for -ise endings (see below). Most words ending in an unstressed ‑our in British English (e.g., behaviour , colour , favour , flavour , harbour , honour , humour , labour , neighbour , rumour , splendour ) end in ‑or in American English ( behavior , color , favor , flavor , harbor , honor , humor , labor , neighbor , rumor , splendor ). Wherever

2375-547: Is also a key substance in the chemical industry . It is most commonly used in fertilizer manufacture but is also important in mineral processing , oil refining , wastewater processing , and chemical synthesis . It has a wide range of end applications, including in domestic acidic drain cleaners , as an electrolyte in lead-acid batteries , as a dehydrating compound, and in various cleaning agents . Sulfuric acid can be obtained by dissolving sulfur trioxide in water. Although nearly 100% sulfuric acid solutions can be made,

2470-499: Is called acid mine drainage (AMD) or acid rock drainage (ARD). The Fe can be further oxidized to Fe : The Fe produced can be precipitated as the hydroxide or hydrous iron oxide : The iron(III) ion ("ferric iron") can also oxidize pyrite: When iron(III) oxidation of pyrite occurs, the process can become rapid. pH values below zero have been measured in ARD produced by this process. ARD can also produce sulfuric acid at

2565-399: Is dropped for other derivations, for example, central , fibrous , spectral . However, the existence of related words without e before the r is not proof for the existence of an -re British spelling: for example, entry and entrance come from enter , which has not been spelled entre for centuries. The difference relates only to root words; -er rather than -re is universal as

2660-402: Is formed by atmospheric oxidation of sulfur dioxide in the presence of water – i.e. oxidation of sulfurous acid . When sulfur-containing fuels such as coal or oil are burned, sulfur dioxide is the main byproduct (besides the chief products carbon oxides and water). Sulfuric acid is formed naturally by the oxidation of sulfide minerals, such as pyrite : The resulting highly acidic water

2755-490: Is generally preferred over oe and often over ae , but oe and ae are sometimes found in academic and scientific writing as well as government publications (for example, the fee schedule of the Ontario Health Insurance Plan ) and some words such as palaeontology or aeon . In Australia, it can go either way, depending on the word: for instance, medieval is spelled with the e rather than ae , following

2850-536: Is known as the Pacific Parlour car, not Pacific Parlor . Proper names such as Pearl Harbor or Sydney Harbour are usually spelled according to their native-variety spelling vocabulary. The name of the herb savory is spelled thus everywhere, although the related adjective savo(u)ry , like savo(u)r , has a u in the UK. Honor (the name) and arbor (the tool) have -or in Britain, as mentioned above, as does

2945-421: Is passed through the catalytic converter bed column again achieving up to 99.8% conversion of SO 2 to SO 3 and the gases are again passed through the final absorption column thus achieving not only high conversion efficiency for SO 2, but also enabling production of a higher concentration of sulfuric acid. The industrial production of sulfuric acid involves proper control of temperatures and flow rates of

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3040-493: Is prepared by slowly adding 98% sulfuric acid to an equal volume of water, with good stirring: the temperature of the mixture can rise to 80 °C (176 °F) or higher. Sulfuric acid contains not only H 2 SO 4 molecules, but is actually an equilibrium of many other chemical species, as it is shown in the table below. Sulfuric acid is a colorless oily liquid, and has a vapor pressure of <0.001 mmHg at 25 °C and 1 mmHg at 145.8 °C, and 98% sulfuric acid has

3135-593: Is sometimes used. The ratio between -ise and -ize stood at 3:2 in the British National Corpus up to 2002. The spelling -ise is more commonly used in UK mass media and newspapers, including The Times (which switched conventions in 1992), The Daily Telegraph , The Economist and the BBC . The Government of the United Kingdom additionally uses -ise , stating "do not use Americanisms" justifying that

3230-714: Is standard worldwide and complection is rare. However, the adjective complected (as in "dark-complected"), although sometimes proscribed, is on equal ground in the U.S. with complexioned. It is not used in this way in the UK, although there exists a rare alternative meaning of complicated . In some cases, words with "old-fashioned" spellings are retained widely in the U.S. for historical reasons (cf. connexionalism ). Many words, especially medical words, that are written with ae/æ or oe/œ in British English are written with just an e in American English. The sounds in question are /iː/ or /ɛ/ (or, unstressed, /i/ , /ɪ/ or /ə/ ). Examples (with non-American letter in bold ):

3325-428: Is substantially less hazardous without the oxidative and dehydrating properties; though, it is handled with care for its acidity. Sulfuric acid is a very important commodity chemical; a country's sulfuric acid production is a good indicator of its industrial strength. Many methods for its production are known, including the contact process , the wet sulfuric acid process , and the lead chamber process . Sulfuric acid

3420-581: Is taught in schools nationwide as part of the Australian curriculum. The most notable countrywide use of the -or ending is for one of the country's major political parties, the Australian Labor Party , which was originally called "the Australian Labour Party" (name adopted in 1908), but was frequently referred to as both "Labour" and "Labor". The "Labor" was adopted from 1912 onward due to

3515-471: Is the usual form of the male given name, as a surname both the spellings Peter and Petre (the latter notably borne by a British lord ) are found. For British accoutre , the American practice varies: the Merriam-Webster Dictionary prefers the -re spelling, but The American Heritage Dictionary of the English Language prefers the -er spelling. More recent French loanwords keep

3610-469: Is then washed with water and dried with sulfuric acid. To conserve energy, the mixture is heated by exhaust gases from the catalytic converter by heat exchangers. Sulfur dioxide and dioxygen then react as follows: According to the Le Chatelier's principle , a lower temperature should be used to shift the chemical equilibrium towards the right, hence increasing the percentage yield. However too low of

3705-481: Is used in both British and American English to show that the c is pronounced /k/ rather than /s/ . The spellings euchre and ogre are also the same in both British and American English. Fire and its associated adjective fiery are the same in both British and American English, although the noun was spelled fier in Old and Middle English. Theater is the prevailing American spelling used to refer to both

3800-466: The H 3 SO + 4 and HSO − 4 ions are high due to an intramolecular proton-switch mechanism (analogous to the Grotthuss mechanism in water), making sulfuric acid a good conductor of electricity. It is also an excellent solvent for many reactions. The hydration reaction of sulfuric acid is highly exothermic , dilution. As indicated by its acid dissociation constant , sulfuric acid

3895-578: The -meter suffix (from Ancient Greek - μέτρον métron , via French -mètre ) normally had the -re spelling from earliest use in English but were superseded by -er . Examples include thermometer and barometer . The e preceding the r is kept in American-inflected forms of nouns and verbs, for example, fibers , reconnoitered , centering , which are fibres , reconnoitred , and centring respectively in British English. According to

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3990-560: The -ise form as an alternative. Publications by Oxford University Press (OUP)—such as Henry Watson Fowler 's A Dictionary of Modern English Usage , Hart's Rules , and The Oxford Guide to English Usage —also recommend -ize . However, Robert Allan's Pocket Fowler's Modern English Usage considers either spelling to be acceptable anywhere but the U.S. American spelling avoids -ise endings in words like organize , realize and recognize . British spelling mostly uses -ise ( organise , realise , recognise ), though -ize

4085-450: The -re spelling in American English. These are not exceptions when a French-style pronunciation is used ( /rə/ rather than /ə(r)/ ), as with double entendre , genre and oeuvre . However, the unstressed /ə(r)/ pronunciation of an -er ending is used more (or less) often with some words, including cadre , macabre , maître d' , Notre Dame , piastre , and timbre . The -re endings are mostly standard throughout

4180-483: The Canadian Medical Association 's Canadian specialty profile of Obstetrics/gynecology ). Pediatrician is preferred roughly 10 to 1 over paediatrician , while foetal and oestrogen are similarly uncommon. Words that can be spelled either way in American English include a esthetics and arch a eology (which usually prevail over esthetics and archeology ), as well as pal a estra , for which

4275-534: The OED , centring is a "word ... of 3 syllables (in careful pronunciation)" (i.e., /ˈsɛntərɪŋ/ ), yet there is no vowel in the spelling corresponding to the second syllable ( /ə/ ). The OED third edition (revised entry of June 2016) allows either two or three syllables. On the Oxford Dictionaries Online website, the three-syllable version is listed only as the American pronunciation of centering . The e

4370-448: The stratosphere , the atmosphere's second layer that is generally between 10 and 50 km above Earth's surface, sulfuric acid is formed by the oxidation of volcanic sulfur dioxide by the hydroxyl radical : Because sulfuric acid reaches supersaturation in the stratosphere, it can nucleate aerosol particles and provide a surface for aerosol growth via condensation and coagulation with other water-sulfuric acid aerosols. This results in

4465-418: The stratospheric aerosol layer . The permanent Venusian clouds produce a concentrated acid rain, as the clouds in the atmosphere of Earth produce water rain. Jupiter 's moon Europa is also thought to have an atmosphere containing sulfuric acid hydrates. Sulfuric acid is produced from sulfur , oxygen and water via the conventional contact process (DCDA) or the wet sulfuric acid process (WSA). In

4560-475: The theatre spelling. (The word "theater" in American English is a place where both stage performances and screenings of films take place, but in British English a "theatre" is where stage performances take place but not film screenings – these take place in a cinema, or "picture theatre" in Australia.) In the United States, the spelling theatre is sometimes used when referring to the art form of theatre, while

4655-515: The u has since been dropped: ambassadour , emperour , errour , governour , horrour , inferiour , mirrour , perturbatour , superiour , tenour , terrour , tremour . Johnson, unlike Webster, was not an advocate of spelling reform, but chose the spelling best derived, as he saw it, from among the variations in his sources. He preferred French over Latin spellings because, as he put it, "the French generally supplied us". English speakers who moved to

4750-435: The u : In American usage, derivatives and inflected forms are built by simply adding the suffix in all cases (for example, favorite , savory etc.) since the u is absent to begin with. American usage, in most cases, keeps the u in the word glamour , which comes from Scots , not Latin or French. Glamor is sometimes used in imitation of the spelling reform of other -our words to -or . Nevertheless,

4845-649: The ‑our/or group do not have a Latin counterpart that ends in ‑or ; for example, armo(u)r , behavio(u)r , harbo(u)r , neighbo(u)r ; also arbo(u)r , meaning "shelter", though senses "tree" and "tool" are always arbor , a false cognate of the other word. The word arbor would be more accurately spelled arber or arbre in the US and the UK, respectively, the latter of which is the French word for "tree". Some 16th- and early 17th-century British scholars indeed insisted that ‑or be used for words from Latin (e.g., color ) and ‑our for French loans; however, in many cases,

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4940-441: The 17th and 18th centuries, whereas there are thousands of examples of their -our counterparts. One notable exception is honor . Honor and honour were equally frequent in Britain until the 17th century; honor only exists in the UK now as the spelling of Honor Oak , a district of London, and of the occasional given name Honor . In derivatives and inflected forms of the -our/or words, British usage depends on

5035-593: The 1970s, but had by then been overtaken by connection in regular usage (for example, in more popular newspapers). Connexion (and its derivatives connexional and connexionalism ) is still in use by the Methodist Church of Great Britain to refer to the whole church as opposed to its constituent districts, circuits and local churches, whereas the US-majority United Methodist Church uses Connection . Complexion (which comes from complex )

5130-704: The American National Theatre was referred to by The New York Times as the "American National Theater ", but the organization uses "re" in the spelling of its name. The John F. Kennedy Center for the Performing Arts in Washington, D.C. has the more common American spelling theater in its references to the Eisenhower Theater, part of the Kennedy Center. Some cinemas outside New York also use

5225-413: The American usage along with numerous other words such as eon or fetus , while other words such as oestrogen or paediatrician are spelled the British way. The Macquarie Dictionary also notes a growing tendency towards replacing ae and oe with e worldwide and with the exception of manoeuvre, all British or American spellings are acceptable variants. Elsewhere, the British usage prevails, but

5320-581: The Anglo-French spelling for defense and offense , which are defence and offence in British English. Likewise, there are the American pretense and British pretence ; but derivatives such as defensive , offensive , and pretension are always thus spelled in both systems. Australian and Canadian usages generally follow British usage. The spelling connexion is now rare in everyday British usage, its use lessening as knowledge of Latin attenuates, and it has almost never been used in

5415-637: The British usage of -our . This coincided with a renewed interest in Canadian English, and the release of the updated Gage Canadian Dictionary in 1997 and the first Canadian Oxford Dictionary in 1998. Historically, most libraries and educational institutions in Canada have supported the use of the Oxford English Dictionary rather than the American Webster's Dictionary . Today, the use of

5510-465: The Commonwealth. The -er spellings are recognized as minor variants in Canada, partly due to United States influence. They are sometimes used in proper names (such as Toronto's controversially named Centerpoint Mall ). For advice / advise and device / devise , American English and British English both keep the noun–verb distinction both graphically and phonetically (where the pronunciation

5605-598: The English Language ("ADEL", "Webster's Dictionary", 1828). Webster was a proponent of English spelling reform for reasons both philological and nationalistic. In A Companion to the American Revolution (2008), John Algeo notes: "it is often assumed that characteristically American spellings were invented by Noah Webster. He was very influential in popularizing certain spellings in the United States, but he did not originate them. Rather [...] he chose already existing options such as center, color and check for

5700-482: The Greek-style ligature as, for example, in maelstrom or toe ; the same is true for the British form aeroplane (compare other aero- words such as aerosol ) . The now chiefly North American airplane is not a respelling but a recoining, modelled after airship and aircraft . The word airplane dates from 1907, at which time the prefix aero- was trisyllabic, often written aëro- . In Canada, e

5795-515: The US: the more common connection has become the standard worldwide. According to the Oxford English Dictionary , the older spelling is more etymologically conservative, since the original Latin word had -xio- . The American usage comes from Webster , who abandoned -xion and preferred -ction . Connexion was still the house style of The Times of London until the 1980s and was still used by Post Office Telecommunications for its telephone services in

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5890-575: The United Kingdom had little effect on today's American spellings and vice versa. For the most part, the spelling systems of most Commonwealth countries and Ireland closely resemble the British system. In Canada, the spelling system can be said to follow both British and American forms, and Canadians are somewhat more tolerant of foreign spellings when compared with other English-speaking nationalities. Australian English mostly follows British spelling norms but has strayed slightly, with some American spellings incorporated as standard. New Zealand English

5985-491: The United States took these preferences with them. In the early 20th century, H. L. Mencken notes that " honor appears in the 1776 Declaration of Independence , but it seems to have been put there rather by accident than by design". In Jefferson 's original draft it is spelled "honour". In Britain, examples of behavior , color , flavor , harbor , and neighbor rarely appear in Old Bailey court records from

6080-423: The United States use Centre in their names. Examples include the villages of Newton Centre and Rockville Centre , the city of Centreville , Centre County and Centre College . Sometimes, these places were named before spelling changes but more often the spelling serves as an affectation. Proper names are usually spelled according to their native-variety spelling vocabulary; so, for instance, although Peter

6175-498: The acid produced in the lead chamber itself (<70% to avoid contamination with nitrosylsulfuric acid ) and tower acid being the acid recovered from the bottom of the Glover tower. They are now obsolete as commercial concentrations of sulfuric acid, although they may be prepared in the laboratory from concentrated sulfuric acid if needed. In particular, "10 M" sulfuric acid (the modern equivalent of chamber acid, used in many titrations ),

6270-441: The action of the catalyst comprises two steps: Hot sulfur trioxide passes through the heat exchanger and is dissolved in concentrated H 2 SO 4 in the absorption tower to form oleum Note that directly dissolving SO 3 in water is impractical due to the highly exothermic nature of the reaction. Acidic vapor or mists are formed instead of a liquid. Oleum is reacted with water to form concentrated H 2 SO 4 . This includes

6365-601: The adjective glamorous often drops the first "u". Saviour is a somewhat common variant of savior in the US. The British spelling is very common for honour (and favour ) in the formal language of wedding invitations in the US. The name of the Space Shuttle Endeavour has a u in it because the spacecraft was named after British Captain James Cook 's ship, HMS Endeavour . The (former) special car on Amtrak 's Coast Starlight train

6460-507: The building itself, as noted above, generally is spelled theater . For example, the University of Wisconsin–Madison has a "Department of Theatre and Drama", which offers courses that lead to the "Bachelor of Arts in Theatre ", and whose professed aim is "to prepare our graduate students for successful 21st Century careers in the theatre both as practitioners and scholars". Some placenames in

6555-426: The close historic, economic, and cultural relationship with the United States, -or endings are also sometimes used. Throughout the late 19th and early to mid-20th century, most Canadian newspapers chose to use the American usage of -or endings, originally to save time and money in the era of manual movable type . However, in the 1990s, the majority of Canadian newspapers officially updated their spelling policies to

6650-416: The contact process is double contact double absorption (DCDA). In this process the product gases (SO 2 ) and (SO 3 ) are passed through absorption towers twice to achieve further absorption and conversion of SO 2 to SO 3 and production of higher grade sulfuric acid. SO 2 -rich gases enter the catalytic converter, usually a tower with multiple catalyst beds, and are converted to SO 3 , achieving

6745-837: The conversion of H 2 SO 4 to [H 3 SO 4 ] by the HF/ SbF 5 system. Even dilute sulfuric acid reacts with many metals via a single displacement reaction, like other typical acids , producing hydrogen gas and salts (the metal sulfate). It attacks reactive metals (metals at positions above copper in the reactivity series ) such as iron , aluminium , zinc , manganese , magnesium , and nickel . Concentrated sulfuric acid can serve as an oxidizing agent , releasing sulfur dioxide: Lead and tungsten , however, are resistant to sulfuric acid. Hot concentrated sulfuric acid oxidizes carbon (as bituminous coal ) and sulfur : Benzene and many derivatives undergo electrophilic aromatic substitution with sulfuric acid to give

6840-412: The corresponding sulfonic acids : Sulfuric acid can be used to produce hydrogen from water : The compounds of sulfur and iodine are recovered and reused, hence the process is called the sulfur–iodine cycle . This process is endothermic and must occur at high temperatures, so energy in the form of heat has to be supplied. The sulfur–iodine cycle has been proposed as a way to supply hydrogen for

6935-606: The corresponding sulfate or bisulfate. Sulfuric acid reacts with sodium chloride , and gives hydrogen chloride gas and sodium bisulfate : Aluminium sulfate , also known as paper maker's alum, is made by treating bauxite with sulfuric acid: Sulfuric acid can also be used to displace weaker acids from their salts. Reaction with sodium acetate , for example, displaces acetic acid , CH 3 COOH , and forms sodium bisulfate : Similarly, treating potassium nitrate with sulfuric acid produces nitric acid . When combined with nitric acid , sulfuric acid acts both as an acid and

7030-403: The dramatic arts and buildings where stage performances and screenings of films take place (i.e., " movie theaters "); for example, a national newspaper such as The New York Times would use theater in its entertainment section. However, the spelling theatre appears in the names of many New York City theatres on Broadway (cf. Broadway theatre) and elsewhere in the United States. In 2003,

7125-399: The dusting tower, cooling pipes, scrubbers, drying tower, arsenic purifier and testing box. Sulfur dioxide has many impurities such as vapours, dust particles and arsenous oxide . Therefore, it must be purified to avoid catalyst poisoning (i.e.: destroying catalytic activity and loss of efficiency). In this process, the gas is washed with water, and dried by sulfuric acid. In the dusting tower,

7220-703: The ending became ‑our to match the later Old French spelling. The ‑our ending was used not only in new English borrowings, but was also applied to the earlier borrowings that had used ‑or . However, ‑or was still sometimes found. The first three folios of Shakespeare 's plays used both spellings before they were standardised to ‑our in the Fourth Folio of 1685. After the Renaissance , new borrowings from Latin were taken up with their original ‑or ending, and many words once ending in ‑our (for example, chancellour and governour ) reverted to ‑or . A few words of

7315-406: The etymology was not clear, and therefore some scholars advocated ‑or only and others ‑our only. Webster's 1828 dictionary had only -or and is given much of the credit for the adoption of this form in the United States. By contrast, Johnson's 1755 (pre-U.S. independence and establishment) dictionary used -our for all words still so spelled in Britain (like colour ), but also for words where

7410-441: The first stage of conversion. The exit gases from this stage contain both SO 2 and SO 3 which are passed through intermediate absorption towers where sulfuric acid is trickled down packed columns and SO 3 reacts with water increasing the sulfuric acid concentration. Though SO 2 too passes through the tower it is unreactive and comes out of the absorption tower. This stream of gas containing SO 2 , after necessary cooling

7505-499: The first step, sulfur is burned to produce sulfur dioxide. American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography , the two most notable variations being British and American spelling. Many of the differences between American and British or Commonwealth English date back to

7600-399: The gases as both the conversion efficiency and absorption are dependent on these. Sulfuric acid Sulfuric acid ( American spelling and the preferred IUPAC name ) or sulphuric acid ( Commonwealth spelling ), known in antiquity as oil of vitriol , is a mineral acid composed of the elements sulfur , oxygen , and hydrogen , with the molecular formula H 2 SO 4 . It

7695-669: The influence of the American labor movement and King O'Malley . On top of that, some place names in South Australia such as Victor Harbor , Franklin Harbor or Outer Harbor are usually spelled with the -or spellings. Aside from that, -our is now almost universal in Australia but the -or endings remain a minority variant. New Zealand English , while sharing some words and syntax with Australian English , follows British usage. In British English, some words from French, Latin or Greek end with

7790-414: The nature of the suffix used. The u is kept before English suffixes that are freely attachable to English words (for example in humourless , neighbourhood , and savoury ) and suffixes of Greek or Latin origin that have been adopted into English (for example in behaviourism , favourite , and honourable ). However, before Latin suffixes that are not freely attachable to English words,

7885-593: The simplicity, analogy or etymology". William Shakespeare 's first folios , for example, used spellings such as center and color as much as centre and colour . Webster did attempt to introduce some reformed spellings, as did the Simplified Spelling Board in the early 20th century, but most were not adopted. In Britain, the influence of those who preferred the Norman (or Anglo-French ) spellings of words proved to be decisive. Later spelling adjustments in

7980-475: The simplified form palestra is described by Merriam-Webster as "chiefly Brit[ish]." This is a reverse of the typical rule, where British spelling uses the ae / oe and American spelling simply uses e . Words that can be spelled either way in British English include cham a eleon , encyclop a edia , hom o eopathy , medi a eval (a minor variant in both AmE and BrE ), f o etid and f o etus . The spellings f o etus and f o etal are Britishisms based on

8075-410: The sounds became monophthongs , and later applied to words not of Greek origin, in both Latin (for example, cœli ) and French (for example, œuvre ). In English, which has adopted words from all three languages, it is now usual to replace Æ/æ with Ae/ae and Œ/œ with Oe/oe . In many words, the digraph has been reduced to a lone e in all varieties of English: for example, o economics , pr

8170-672: The spelling "is often seen as such". The -ize form is known as Oxford spelling and is used in publications of the Oxford University Press, most notably the Oxford English Dictionary , and of other academic publishers such as Nature , the Biochemical Journal and The Times Literary Supplement . It can be identified using the IETF language tag en-GB-oxendict (or, historically, by en-GB-oed ). In Ireland, India, Australia, and New Zealand -ise spellings strongly prevail:

8265-608: The spellings with just e are increasingly used. Manoeuvre is the only spelling in Australia, and the most common one in Canada, where maneuver and manoeuver are also sometimes found. The -ize spelling is often incorrectly seen in Britain as an Americanism. It has been in use since the 15th century, predating the -ise spelling by over a century. The verb-forming suffix -ize comes directly from Ancient Greek -ίζειν ( -ízein ) or Late Latin -izāre , while -ise comes via French -iser . The Oxford English Dictionary ( OED ) recommends -ize and lists

8360-445: The subsequent loss of SO 3 at the boiling point brings the concentration to 98.3% acid. The 98.3% grade, which is more stable in storage, is the usual form of what is described as "concentrated sulfuric acid". Other concentrations are used for different purposes. Some common concentrations are: "Chamber acid" and "tower acid" were the two concentrations of sulfuric acid produced by the lead chamber process , chamber acid being

8455-401: The sulfur dioxide is exposed to a steam which removes the dust particles. After the gas is cooled, the sulfur dioxide enters the washing tower where it is sprayed by water to remove any soluble impurities. In the drying tower, sulfuric acid is sprayed on the gas to remove the moisture from it. Finally, the arsenic oxide is removed when the gas is exposed to ferric hydroxide . The next step to

8550-412: The vowel is unreduced in pronunciation (e.g., devour , contour , flour , hour , paramour , tour , troubadour , and velour ), the spelling is uniform everywhere. Most words of this kind came from Latin, where the ending was spelled ‑or . They were first adopted into English from early Old French , and the ending was spelled ‑our , ‑or or ‑ur . After the Norman conquest of England ,

8645-428: The word pallor . As a general noun, rigour / ˈ r ɪ ɡ ər / has a u in the UK; the medical term rigor (sometimes / ˈ r aɪ ɡ ər / ) does not, such as in rigor mortis , which is Latin. Derivations of rigour / rigor such as rigorous , however, are typically spelled without a u , even in the UK. Words with the ending -irior , -erior or similar are spelled thus everywhere. The word armour

8740-407: The work of Noah Webster and, in particular, his An American Dictionary of the English Language , first published in 1828. Webster's efforts at spelling reform were effective in his native country, resulting in certain well-known patterns of spelling differences between the American and British varieties of English. However, English-language spelling reform has rarely been adopted otherwise. As

8835-413: Was easily absorbed into water, producing sulfuric acid . This process was improved remarkably by shrinking the particle size of the catalyst (e.g. ≤ 5000 microns), a process discovered by two chemists of BASF in 1914. The process can be divided into four stages: Purification of the air and sulfur dioxide (SO 2 ) is necessary to avoid catalyst poisoning (i.e. removing catalytic activities). The gas

8930-428: Was once somewhat common in American usage but has disappeared except in some brand names such as Under Armour . The agent suffix -or ( separator , elevator , translator , animator , etc.) is spelled thus both in American and British English. Commonwealth countries normally follow British usage. Canadian English most commonly uses the -our ending and -our- in derivatives and inflected forms. However, owing to

9025-929: Was published. Following this, -re became the most common usage in Britain. In the United States, following the publication of Webster's Dictionary in the early 19th century, American English became more standardized, exclusively using the -er spelling. In addition, spelling of some words have been changed from -re to -er in both varieties. These include September , October , November , December , amber, blister , cadaver , chamber , chapter , charter , cider , coffer , coriander , cover , cucumber , cylinder , diaper , disaster , enter , fever , filter , gender , leper , letter , lobster , master , member , meter (measuring instrument) , minister , monster , murder , number , offer , order , oyster , powder , proper , render , semester , sequester , sinister , sober , surrender , tender , and tiger . Words using

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