Titration and Testees: Difference between pages
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{{Infobox Television |
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{{This|''volumetric titration''|Titration (disambiguation)}} |
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| show_name = Testees |
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{{dablink|In [[medicine]], titration is the process of gradually adjusting the dose of a medication until the desired effect is achieved.}} |
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| image = |
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{{distinguish|Tetration}} |
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| caption = |
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[[Image:Titration.gif|frame|Titration setup: the titrant drops from the [[burette]] into the [[analyte]] solution in the [[laboratory flask|flask]]. An indicator present then changes color permanently at the [[Endpoint (chemistry)|endpoint]].]] |
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| format = [[Comedy]] |
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| runtime = |
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| creator = [[Kenny Hotz]] |
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| starring = Steve Markle<br />Jeff Kassel |
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| country = {{CAN}}<br>{{USA}} |
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| network = [[FX (TV network)|FX]]<br>[[Showcase (TV channel)|Showcase]] |
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| producer = |
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| executive_producer = [[Kenny Hotz]] |
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| co_exec = |
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| consulting_producer = |
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| composer = |
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| theme_music_composer = |
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| picture_format = |
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| first_aired = October 9, 2008 |
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| last_aired = present |
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| num_seasons = 1 |
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| num_episodes = 1 |
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| list_episodes = |
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| related = |
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| language = English |
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| imdb_id = 1262403 |
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| tv_com_id = 75927 |
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| website = |
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}} |
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'''''Testees''''' is a [[Canada|Canadian]] and [[United States|American]] [[television series]], which debuted on Thursday, [[October 9]] [[2008]] at 10:30 PM EST on [[FX Networks|FX]]<ref>[http://www.thefutoncritic.com/news.aspx?id=20080715fx02 FX Picks Up New Comedy Series "Testees" (working title)]</ref> and will debut on October 14, 2008 on Showcase in Canada. The series follows two friends ([[Steve Markle]] and [[Jeff Kassel]]) as they work as human test subjects at Testico, a product testing facility. Besides being an obvious play on [[testicle|testes]] – including the descended double "e" in its logo – the name of the show plays up the vulnerability of test subjects, which is the source of much of the humor in the series. |
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'''Titration''' is a common laboratory method of [[quantitative]] [[Analytical chemistry|chemical analysis]] that is used to determine the unknown [[concentration]] of a known [[reactant]]. Because volume measurements play a key role in titration, it is also known as ''volumetric analysis''. |
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A [[reagent]], called the ''titrant'', of known concentration (a [[standard solution]]) and [[volume]] is used to react with a solution of the [[analyte]], whose concentration is not known. Using a calibrated [[burette]] to add the titrant, it is possible to determine the exact amount that has been consumed when the ''endpoint'' is reached. The endpoint is the point at which the titration is complete, as determined by an indicator (see below). This is ideally the same volume as the ''equivalence point'' - the volume of added titrant at which the number of [[Mole (unit)|moles]] of titrant is equal to the number of moles of analyte, or some multiple thereof (as in [[polyprotic]] acids). In the classic strong acid-strong base titration, the endpoint of a titration is the point at which the pH of the reactant is just about equal to 7, and often when the solution permanently changes color due to an [[pH indicator|indicator]]. There are however many different types of titrations (see below). |
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== References == |
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Many methods can be used to indicate the endpoint of a reaction; titrations often use [[visual]] indicators (the reactant mixture changes colour). In simple [[acid-base titration]]s a pH indicator may be used, such as [[phenolphthalein]], which becomes pink when a certain pH (about 8.2) is reached or exceeded. Another example is [[methyl orange]], which is red in acids and yellow in alkali solutions. |
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{{Reflist}} |
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{{Refbegin}} |
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{{Refend}} |
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[[Category:2008 television series debuts]] |
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Not every titration requires an indicator. In some cases, either the reactants or the products are strongly coloured and can serve as the "indicator". For example, an [[redox titration|oxidation-reduction titration]] using [[potassium permanganate]] (pink/purple) as the titrant does not require an indicator. When the titrant is reduced, it turns colourless. After the equivalence point, there is excess titrant present. The equivalence point is identified from the first faint pink color that persists in the solution being titrated. |
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[[Category:2008 Canadian television series debuts]] |
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[[Category:Canadian comedy television series]] |
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Due to the logarithmic nature of the pH curve, the transitions are, in general, extremely sharp; and, thus, a single drop of titrant just before the ''endpoint'' can change the pH significantly — leading to an immediate colour change in the indicator. There is a slight difference between the change in indicator color and the actual equivalence point of the titration. This error is referred to as an indicator error, and it is indeterminate. |
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[[Category:Showcase network shows]] |
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[[Category:FX network shows]] |
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==History and etymology== |
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The word "titration" comes from the Latin word ''titalus'', meaning inscription or title. The French word ''titre'', also from this origin, means rank. Titration, by definition, is the determination of rank or concentration of a solution with respect to water with a pH of 7 (which is the pH of pure water). |
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The origins of volumetric analysis are in late-18th-century French chemistry. Francois Antoine Henri Descroizilles developed the first burette (which looked more like a graduated cylinder) in 1791. [[Joseph Louis Gay-Lussac]] developed an improved version of the burette that included a side arm, and coined the terms "[[pipette]]" and "[[burette]]" in an 1824 paper on the standardization of indigo solutions. A major breakthrough in the methodology and popularization of volumetric analysis was due to [[Karl Friedrich Mohr]], who redesigned the burette by placing a clamp and a tip at the bottom, and wrote the first textbook on the topic, ''Lehrbuch der chemisch-analytischen Titrirmethode'' (''Textbook of analytical-chemical titration methods''), published in 1855.<ref>Louis Rosenfeld. ''Four Centuries of Clinical Chemistry''. CRC Press, 1999, p. 72-75.</ref> |
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==Preparing a sample for titration== |
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In a titration, both titrant and analyte are required to be in a liquid (solution) form. If the sample is not a liquid or solution, the samples must be dissolved. If the analyte is very concentrated in the sample, it might be useful to dilute the sample. |
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Although the vast majority of titrations are carried out in aqueous solution, other solvents such as [[Acetic acid|glacial acetic acid]] or [[ethanol]] (in [[petrochemistry]]) are used for special purposes. |
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A measured amount of the sample can be given in the flask and then be dissolved or diluted. The mathematical result of the titration can be calculated directly with the measured amount. Sometimes the sample is dissolved or diluted beforehand, and a measured amount of the solution is used for titration. In this case the dissolving or diluting must be done accurately with a known [[coefficient]] because the mathematical result of the titration must be multiplied with this factor. |
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Many titrations require buffering to maintain a certain [[pH]] for the reaction. Therefore, [[buffer solution]]s are added to the reactant solution in the flask. |
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Some titrations require "masking" of a certain ion. This can be necessary when two reactants in the sample would react with the titrant and only one of them must be analysed, or when the reaction would be disturbed or inhibited by this ion. In this case another solution is added to the sample, which "masks" the unwanted ion (for instance by a weak binding with it or even forming a solid insoluble substance with it). |
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Some [[redox]] reactions may require heating the solution with the sample and titration while the solution is still hot (to increase the [[reaction rate]]). |
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==Procedure== |
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A typical titration begins with a [[beaker (glassware)|beaker]] or [[Erlenmeyer flask]] containing a precise volume of the reactant and a small amount of indicator, placed underneath a [[burette]] containing the reagent. By controlling the amount of reagent added to the reactant, it is possible to detect the point at which the indicator changes color. As long as the indicator has been chosen correctly, this should also be the point where the reactant and reagent neutralise each other, and, by reading the scale on the burette, the volume of reagent can be measured. |
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As the concentration of the reagent is known, the number of moles of reagent can be calculated (since <math>concentration = moles / volume(L)</math>). Then, from the chemical equation involving the two substances, the number of moles present in the reactant can be found. Finally, by dividing the number of moles of reactant by its volume, the concentration is calculated. |
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==Titration curves== |
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{{main|Titration curve}} |
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==Types of titrations== |
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Titrations can be classified by the type of reaction. Different types of titration reaction include: |
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*[[Acid-base titration]]s are based on the neutralization reaction between the analyte and an acidic or basic titrant. These most commonly use a pH indicator, a pH meter, or a conductance meter to determine the endpoint. |
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*[[Redox titration]]s are based on an oxidation-reduction reaction between the analyte and titrant. These most commonly use a potentiometer or a redox indicator to determine the endpoint. Frequently either the reactants or the titrant have a colour intense enough that an additional indicator is not needed. |
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*[[Complexometric titration]]s are based on the formation of a [[complex (chemistry)|complex]] between the analyte and the titrant. The [[chelating agent]] [[EDTA]] is very commonly used to titrate metal ions in solution. These titrations generally require specialized [[complexometric indicator|indicator]]s that form weaker complexes with the analyte. A common example is [[Eriochrome Black T]] for the titration of [[calcium]] and [[magnesium]] ions. |
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*A form of titration can also be used to determine the concentration of a [[virus]] or [[bacterium]]. The original sample is diluted (in some fixed ratio, such as 1:1, 1:2, 1:4, 1:8, etc.) until the last dilution does not give a positive test for the presence of the virus. This value, the [[titre]], may be based on [[TCID50]], [[EID50]], [[ELD50]], [[LD50|LD<sub>50</sub>]] or [[Plaque forming units|pfu]]. This procedure is more commonly known as an [[assay]]. |
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*A [[zeta potential titration]] characterizes [[heterogeneous]] systems, such as [[colloid]]s. [[Zeta potential]] plays role of [[indicator]]. One of the purposes is determination of [[iso-electric point]] when [[surface charge]] becomes 0. This can be achieved by changing [[pH]] or adding [[surfactant]]. Another purpose is determination of the optimum dose of the chemical for [[flocculation]] or [[stabilization]]. |
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==Measuring the endpoint of a titration== |
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{{main|Endpoint (chemistry)}} |
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Different methods to determine the endpoint include: |
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*[[pH indicator]]: This is a substance that changes colour in response to a chemical change. An acid-base indicator (e.g., [[phenolphthalein]]) changes colour depending on the [[pH]]. [[Redox indicator]]s are also frequently used. A drop of indicator solution is added to the titration at the start; when the colour changes the endpoint has been reached. |
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*A [[potentiometer]] can also be used. This is an instrument that measures the [[electrode potential]] of the solution. These are used for titrations based on a redox reaction; the potential of the working electrode will suddenly change as the endpoint is reached. |
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*[[pH meter]]: This is a potentiometer that uses an electrode whose potential depends on the amount of H<sup>+</sup> ion present in the solution. (This is an example of an [[ion-selective electrode]]. This allows the pH of the solution to be measured throughout the titration. At the endpoint, there will be a sudden change in the measured pH. It can be more accurate than the indicator method, and is very easily automated. |
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*Conductance: The [[electrical conductivity|conductivity]] of a solution depends on the ions that are present in it. During many titrations, the conductivity changes significantly. (For instance, during an acid-base titration, the H<sup>+</sup> and OH<sup>-</sup> ions react to form neutral H<sub>2</sub>O. This changes the conductivity of the solution.) The total conductance of the solution depends also on the other ions present in the solution (such as counter ions). Not all ions contribute equally to the conductivity; this also depends on the [[electrophoretic mobility|mobility]] of each ion and on the total concentration of ions ([[ionic strength]]). Thus, predicting the change in conductivity is harder than measuring it. |
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*Colour change: In some reactions, the solution changes colour without any added indicator. This is often seen in redox titrations, for instance, when the different oxidation states of the product and reactant produce different colours. |
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*Precipitation: If the reaction forms a solid, then a [[precipitate]] will form during the titration. A classic example is the reaction between Ag<sup>+</sup> and Cl<sup>-</sup> to form the very insoluble salt AgCl. This usually makes it difficult to determine the endpoint precisely. As a result, precipitation titrations often have to be done as "back" titrations (see below). |
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*An [[Calorimeter#Isothermal titration calorimeter|isothermal titration calorimeter]] uses the heat produced or consumed by the reaction to determine the endpoint. This is important in [[biochemistry|biochemical]] titrations, such as the determination of how [[substrate (biochemistry)|substrate]]s bind to [[enzyme]]s. |
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*[[Thermometric Titration|Thermometric titrimetry]] is an extraordinarily versatile technique. This is differentiated from calorimetric titrimetry by the fact that the heat of the reaction (as indicated by temperature rise or fall) is not used to determine the amount of analyte in the sample solution. Instead, the endpoint is determined by ''the rate of temperature change''. |
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*[[Spectroscopy]] can be used to measure the absorption of light by the solution during the titration, if the [[spectrum]] of the reactant, titrant or product is known. The relative amounts of the product and reactant can be used to determine the endpoint. |
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*[[Amperometry]] can be used as a detection technique ([[amperometric titration]]). The current due to the oxidation or reduction of either the reactants or products at a working electrode will depend on the concentration of that species in solution. The endpoint can then be detected as a change in the current. This method is most useful when the excess titrant can be reduced, as in the titration of halides with Ag<sup>+</sup>. (This is handy also in that it ignores precipitates.) |
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===Other terms=== |
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The term [[white titration]] is used when a titration is done "backwards": |
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instead of titrating the original analyte, one adds a known excess of a |
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standard reagent to the solution, then titrates the excess. A back titration |
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is useful if the endpoint of the reverse titration is easier to identify |
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than the endpoint of the normal titration. They are also useful if |
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the reaction between the analyte and the titrant is very slow. |
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==Particular uses== |
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*As applied to [[biodiesel]], titration is the act of determining the [[acidity]] of a sample of [[wiktionary:WVO|WVO]] by the dropwise addition of a known [[base (chemistry)|base]] to the sample while testing with [[pH]] paper for the desired neutral pH=7 reading. By knowing how much base neutralizes an amount of WVO, we discern how much base to add to the entire [[wiktionary:batch|batch]]. |
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*Titrations in the [[petrochemical]] or [[food industry]] to define oils, fats or biodiesel and similar substances. An example procedure for all three can be found here: [http://folk.uio.no/johnv/26thIChO/problems/p1.html]. |
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**[[Acid number]]: an acid-base titration with colour indicator is used to determine the [[Fatty acid#Free fatty acids|free fatty acid]] content. See also: [[Fatty acid#pH|pH of fatty acids]]. |
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**[[Iodine number]]: a redox titration with colour indication, which indicates the amount of [[Fatty acid#Unsaturated fatty acids|unsaturated fatty acids]]. |
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**[[Saponification value]]: an acid-base back titration with colour indicator or potentiometric to get a hint about the average chain length of fatty acids in a fat. |
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**[[Karl Fischer titration]] a method to analyse trace amounts of water in a substance. |
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==References== |
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{{reflist}} |
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==External links== |
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{{commonscat|Titration}} |
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* [http://www.scienceaid.co.uk/chemistry/analytic/titration.html Science aid: Titration] An informative yet simple explanation of titration aimed at teens |
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* [http://www.avogadro.co.uk/miscellany/titration/titreset.htm Titration - apparatus, technique and calculation] |
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* [http://www2.iq.usp.br/docente/gutz/Curtipot_.html Titration freeware - simulation of any pH vs. volume curve, distribution diagrams and real data analysis] |
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* [http://www.metrohm.com/applications/lit/mono/practical-titration.html Free Metrohm Monograph: Practical Titration] |
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* [http://www.metrohm.com/applications/lit/mono/order/thermometric-titration.html Free Metrohm Monograph: Practical Thermometric Titrimetry] |
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* [http://www.mt.com/mt/library/Dummy_Basics_of_Titration_Handbook_0x000248d2000262fc000515e3.jsp Basics of Titration: Free downloadable guide (pdf) from METTLER TOLEDO] |
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{{Analytical chemistry}} |
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[[Category:Titration| ]] |
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[[ar:معايرة]] |
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[[bs:Titracija]] |
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[[ca:Valoració]] |
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[[cs:Titrace]] |
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[[da:Titrering]] |
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[[de:Titration]] |
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[[et:Tiitrimine]] |
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[[el:Στοιχειομετρική ανάλυση]] |
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[[es:Análisis volumétrico]] |
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[[fr:Titrage]] |
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[[it:Titolazione (chimica)]] |
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[[he:טיטור]] |
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[[lv:Titrēšana]] |
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[[hu:Titrálás]] |
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[[nl:Titratie]] |
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[[ja:滴定]] |
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[[no:Titrering]] |
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[[nn:Titrering]] |
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[[pl:Miareczkowanie]] |
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[[pt:Titulação]] |
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[[ru:Титриметрический анализ]] |
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[[scn:Titulazzioni]] |
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[[fi:Titraus]] |
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[[sv:Titrering]] |
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[[zh:滴定]] |
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Revision as of 02:56, 13 October 2008
| Testees | |
|---|---|
| Created by | Kenny Hotz |
| Starring | Steve Markle Jeff Kassel |
| Country of origin |  Canada United States |
| Original language | English |
| No. of seasons | 1 |
| No. of episodes | 1 |
| Production | |
| Executive producer | Kenny Hotz |
| Original release | |
| Network | FX Showcase |
| Release | October 9, 2008 – present |
Testees is a Canadian and American television series, which debuted on Thursday, October 9 2008 at 10:30 PM EST on FX[1] and will debut on October 14, 2008 on Showcase in Canada. The series follows two friends (Steve Markle and Jeff Kassel) as they work as human test subjects at Testico, a product testing facility. Besides being an obvious play on testes – including the descended double "e" in its logo – the name of the show plays up the vulnerability of test subjects, which is the source of much of the humor in the series.