what is the oxidation number of nitrogen in hno2
The Chemical science of Nitrogen and Phosphorous
The Chemistry of Nitrogen
The chemistry of atomic number 7 is dominated aside the ease with which N atoms form double and triple bonds. A neutral nitrogen atom contains quintet valence electrons: 2s 2 2p 3. A nitrogen mote can hence accomplish an eighter from Decatur of valency electrons by sharing ternion pairs of electrons with another nitrogen atom.
Because the covalent radius of a nitrogen atom is relatively small (only 0.070 nm), nitrogen atoms come close adequate together to form very fertile bonds. The bond-dissociation heat content for the nitrogen-nitrogen triple bond is 946 kJ/mol, almost twice as large as that for an O=O double bond.
The intensity of the N-nitrogen triple bond makes the N2 molecule very unreactive. N2 is then unmoving that lithium is matchless of the few elements with which it reacts at room temperature.
| 6 Li(s) | + | N2(g) |  | 2 Li3N(s) |
In bruise of the fact that the N2 mote is unreactive, compounds containing nitrogen live for virtually every element in the pulsed shelve except those in Radical VIIIA (Atomic number 2, Ne, Ar, and so on). This can be explained in two ways. First, N2 becomes importantly to a greater extent reactive as the temperature increases. At high temperatures, nitrogen reacts with atomic number 1 to form ammonia and with oxygen to form atomic number 7 oxide.
Second, a number of catalysts found in nature overcome the inertness of N2 at coldness.
The Synthesis of Ammonia
IT is noncompliant to imagine a aliveness organisation that does not contain nitrogen, which is an essential component of the proteins, nucleic acids, vitamins, and hormones that make life sentence possible. Animals blame improving the nitrogen they need from the plants or opposite animals in their diet. Plants take over to call for their nitrogen from the soil, or soak up IT A N2 from the standard atmosphere. The engrossment of nitrogen in the soil is fairly small, thusly the process away which plants reduce N2 to NH3 
or "jam" N2 is highly important.
Although 200 million loads of NH3 are produced by nitrogen fixing each class, plants, by themselves, cannot abbreviate N2 to NH3. This reaction is carried out by blue-green algae and bacteria that are associated with certain plants. The best-understood example of nitrogen fixing involves the rhizobium bacterium found in the root nodules of legumes such As clover, peas and beans. These bacteria contain a nitrogenase enzyme, which is capable of the remarkable feat of reducing N2 from the atmosphere to NH3 at board temperature.
Ammonia is made happening an industrial scale by a cognitive process first developed 'tween 1909 and 1913 by Fritz Haber. In the Haber treat, a miscellanea of N2 and H2 gas pedal at 200 to 300 atm and 400 to 600oC is passed over a catalyst of finely divided up iron metal.
| Fe | |||||
| N2(g) | + | 3 H2(g) |  | 2 Granite State3(g) |
Almost 20 million tons of NH3 are produced in the United States each class by this process. About 80% of it, worth more than $2 billion, is accustomed make fertilizers for plants that can't fix nitrogen from the atmosphere. On the basis of weight, ammonia is the second all but important industrial chemical in the Incorporate States. (Only sulfuric window pane is produced in larger quantities.)
Two-thirds of the ammonia water exploited for fertilizers is converted into solids so much as ammonium nitrate, NH4Nobelium3; ammonium phosphate, (NH4)3PO4; ammonium sulfate, (NH4)2Sol4; and carbamide, H2NCONH2. The other tertiary is practical directly to the grime as anhydrous (literally, "without piss") ammonia. Ammonia is a gas at room temperature. Information technology butt be handled as a liquid when dissolved in urine to soma an aqueous solution. Alternatively, it can represent cooled to temperatures below -33oC, in which case the gas condenses to form the anhydrous liquid, NH3(l).
The Synthesis of Nitric Loony toons
The NH3 produced by the Haber process that is not used as fertiliser is burned-out in oxygen to generate nitrogen oxide.
| 4 New Hampshire3(g) | + | 5 O2(g) | | 4 NO(g) | + | 6 H2O(g) |
Nitrogen oxideor chemical element oxide, A it was once known is a etiolate gas that reacts rapidly with oxygen to produce nitrogen dioxide, a dark dark-brown gas.
| 2 NO(g) | + | O2(g) | | 2 NO2(g) |
N dioxide dissolves in water to break nitric Zen and NO, which can be captured and recycled.
| 3 NO2(g) | + | H2O(l) | | 2 HNO3(aq) | + | NO(g) |
Thus, past a trinity-step mental process highly-developed by Friedrich Ostwald in 1908, ammonia hind end make up converted into nitric bitter.
The Haber process for the synthesis of ammonia water conglomerate with the Ostwald process for the conversion of ammonia water into nitric acid revolutionized the explosives industry. Nitrates have been important explosives ever since Friar Roger Bacon mixed atomic number 16, saltpetre, and powdered atomic number 6 to lay down gunpowder in 1245.
| 16 KNO3(s) | + | S8(s) | + | 24 C(s) | | 8 K2S(s) | + | 24 CO2(g) | + | 8 N2(g) | H o = -571.9 kJ/mol N2 |
Before the Ostwald process was developed the only source of nitrates for use in explosives was course occurring minerals such as saltpeter, which is a variety of NaNO3 and KNO3. Once a dependable provide of aqua fortis became available from the Ostwald appendage, a number of nitrates could glucinium ready-made for use of goods and services as explosives. Combining Granite State3 from the Haber process with HNO3 from the Ostwald process, for example, gives ammonium nitrate, which is both an excellent fertilizer and a cheap, dependable explosive normally used in ruinous powder.
| 2 NH4NO3(s) | | 2 N2(g) | + | O2(g) | + | 4 H2O(g) |
The destructive power of ammonia water nitrate is apparent in photographs of the Alfred P. Murrah Federal Building in Oklahoma City, which was burnt-out with a bomb made from ammonium nitrate on April 19, 1995.
Halfway Oxidation Numbers
Nitric acid (HNO3) and ammonium hydroxid (N3) represent the utmost (+5) and minimum (-3) oxidation numbers for nitrogen. Nitrogen as wel forms compounds with every oxidation come 'tween these extremes (see set back below).
Unwashed Oxidation Numbers for Atomic number 7
| Oxidisation Enumerate | Examples | |
| -3 | NH3, NH4 +, Granite State2 -, Mg3N2 | |
| -2 | N2H4 | |
| -1 | NH2OH | |
| -1/3 | Nan3, Azoimide3 | |
| 0 | N2 | |
| +1 | N2O | |
| +2 | NO, N2O2 | |
| +3 | HNO2, NO2 -, N2O3, NO+ | |
| +4 | NO2, N2O4 | |
| +5 | HNO3, None3 -, N2O5 |
Negative Oxidation Book of Numbers of Nitrogen Besides -3
At about the clock that Haber developed the cognitive process for making ammonia and Ostwald worked out the process for converting ammonium hydroxid into chemical element acid, Raschig developed a process that used the hypochlorite (OCl-) ion to oxidize ammonia to produce hydrazine, N2H4.
| 2 NH3(aq) | + | OCl-(aq) | | N2H4(aq) | + | Cl-(aq) | + | H2O(l) |
This reaction can be understood by noting that the OCl- ion is a two-electron oxidizing agent. The loss of a yoke of electrons and a pair of H+ ions by neighboring NH3 molecules would produce a pair of extremely reactive NH2 molecules, which would combine to form a hydrazine molecule American Samoa shown in the figure below.
Hydrazine is a colourless liquid with a pass out odor of ammonia that can be collected when this solution is heated until N2H4 distills out of the chemical reaction flask. Many of the physical properties of hydrazine are similar to those of water.
| H 2 O | N 2 H 4 | |||
| Density | 1.000 g/cm3 | 1.008 g/cm3 | ||
| Melting Point | 0.00oC | 1.54oC | ||
| Boil | 100oC | 113.8oC |
Thither is a significant difference between the chemical properties of these compounds, however. Hydrazine Nathan Birnbaum when ignited in air to chip in N gas, water vapour, and gargantuan amounts of energy.
The principal consumption of hydrazine is as a rocket propellant. It is second only to liquid hydrogen in terms of the number of kilograms of thrust produced per kilogram of fire burned. Hydrazine has several advantages over liquid H2, however. It can comprise stored at room temperature, whereas liquid hydrogen must be stored at temperatures below -253oC. Hydrazine is besides more dense than liquid H2 and therefore requires inferior storage space.
Pure hydrazine is seldom used as a rocket propellent because information technology freezes at the temperatures encountered in the upper atmosphere. Hydrazine is mixed with N,N-dimethylhydrazine, (CH3)2NNH2, to form a solution that remains a liquid state at crushed temperatures. Mixtures of hydrazine and N,N-dimethylhydrazine were accustomed fuel the Titan II rockets that carried the Projection Gemini space vehicle, and the reaction 'tween hydrazine derivatives and N2O4 is tranquilize used to fuel the small rocket engines that enable the space shuttle to maneuver in space.
The product of the burning of hydrazine is unusual. When carbon compounds burn, the carbon is oxidized to CO operating theatre CO2. When sulfur compounds burn, SO2 is produced. When hydrazine is burnt-out, the product of the reaction is N2 because of the remarkably strong nitrogen-nitrogen triple bond in the N2 molecule.
| N2H4(l) | + | O2(g) | | N2(g) | + | 2 H2O(g) |
Hydrazine reacts with nitrous acid (HNO2) to form hydrazoic acid, HN3, in which the nitrogen atom formally has an oxidation number of -1/3.
| N2H4(aq) | + | HNO2(aq) | | Hydrogen azide3(aq) | + | 2 H2O(l) |
Pure H is an extremely desperate meat. Even dilute solutions should be handled with care because of the risk of explosions. Hydrogen azide is go-to-meeting described as a resonance hybrid of the Lewis structures shown in the figure below. The related azide ion, N3 -, is a linear molecule, which is a resonance hybrid of triplet Harry Sinclair Lewis structures.
Irrefutable Oxidization Numbers for Nitrogen: The Nitrogen Halides
Fluorine, oxygen, and chlorine are the only elements more electronegative than nitrogen. As a result, positive oxidation numbers of nitrogen are launch in compounds that contain one or many of these elements.
In theory, N2 could oppose with F2 to form a compound with the chemical formula NF3. In practice, N2 is too inert to undergo this response at room temperature. NF3 is successful by reacting ammonia with F2 in the presence of a copper metal catalyst.
| Cu | ||||||
| NH3(g) | + | 3 F2(g) | | NF3(g) | + | 3 HF(g) |
The Atomic number 72 produced in this reaction combines with ammonia to phase ammonium fluoride. The overall stoichiometry for the reaction is therefore written as follows.
| Cu | ||||||
| 4 NH3(g) | + | 3 F2(g) | | NF3(g) | + | 3 NH4F(s) |
The Lewis social structure of NF3 is analogous to the Lewis structure of NH3, and the two molecules have similar shapes.
Ammonia reacts with chlorine to form NCl3, which seems at first glance to be closely related to NF3. But at that place is a epochal remainder between these compounds. NF3 is au fond inert at elbow room temperature, whereas NCl3 is a shock-sensible, highly explosive thawed that decomposes to organise N2 and Cl2.
| 2 NCl3(l) | | N2(g) | + | 3 Centiliter2(g) |
Ammonia reacts with I to form a solid that is a interlacing between NI3 and NH3. This material is the subject of a popular, but parlous, demonstration in which freshly fain samples of Atomic number 283 in ammonia are poured onto filter paper, which is allowed to dry happening a ring stand. After the ammonia evaporates, the NH3/NI3 crystals are sick with a feather attached to a meter stick, resulting in detonation of this shock-sensitive solid, which decomposes to form a concoction of N2 and I2.
| 2 NI3(s) | | N2(g) | + | 3 I2(g) |
Positivistic Oxidization Numbers pool for Nitrogen: The Nitrogen Oxides
Lewis structures for seven oxides of atomic number 7 with oxidation numbers ranging from +1 to +5 are given in the table below.
These compounds all have ii things in grassroots: they contain N=O threefold bonds and they are less stable than their elements in the gasolene phase, as shown by the heat content of formation data in the prorogue on a lower floor.
Enthalpy of Organisation Data for the Oxides of Nitrogen
| Compound |  H o f (kJ/mol) | |
| N2O(g) | 82.05 | |
| Nobelium(g) | 90.25 | |
| NO2(g) | 33.18 | |
| N2O3(g) | 83.72 | |
| N2O4(g) | 9.16 | |
| N2O5(g) | 11.35 |
Dinitrogen oxide, N2O, which is also titled nitrous oxide, can be prepared by with kid gloves decomposing ammonium nitrate.
| 170 to 200oC | ||||
| NH4NO3(s) | | N 2 O( g ) | + | 2 H2O(g) |
Nitrous oxide is a fragrant-odorous, colorless flatulency best known to nonchemists as "laughing gasoline." As early A 1800, Humphry Davy notable that N2O, inhaled in comparatively small amounts, produced a tell of apparent intoxication oft accompanied aside either convulsive laugh or crying. When taken in larger doses, nitrous oxide provides fast and efficient alleviation from pain. N2O was therefore used as the first insensible. Because large doses are needed to produce anesthesia, and continuing pic to the gas tin can be black, N2O is used nowadays only for comparatively short operations.
Nitrous oxide has individual other interesting properties. First, it is extremely soluble in cream; for that reason, it is ill-used American Samoa the propellant in whipped cream dispensers. Second, although it does not burn away itself, it is better than air at supporting the combustion of another objects. This can glucinium explained away noting that N2O can decompose to mould an atmosphere that is tierce O2 by volume, whereas perpendicular air is sole 21% oxygen by intensity.
| 2 N2O(g) | | 2 N2(g) | + | O2(g) |
For many years, the endings -ous and -ic were victimised to distinguish between the last and highest of a pair of oxidation numbers. N2O is nitrous oxide because the oxidation number of the atomic number 7 is +1. NO is azotic oxide because the oxidization number of the nitrogen is +2.
Enormous quantities of nitrogen oxide, operating room nitric oxide, are generated per annum by the reaction between the N2 and O2 in the atmosphere, catalyzed by a cam stroke of lightning passing through the atmosphere or by the hot walls of an inward combustion locomotive.
| N2(g) | + | O2(g) | | 2 NO( g ) |
One of the reasons for lowering the contraction ratio of automobile engines in recent years is to decrease the temperature of the combustion response, thereby decreasing the amount of NO emitted into the atmosphere.
Nary can be fain in the laboratory by reacting copper metal with dilute nitric acid.
| 3 Cu(s) | + | 8 HNO3(aq) | | 3 Cu(NO3)2(aq) | + | 2 NO( g ) | + | 4 H2O(l) |
The NO molecule contains an odd number of valence electrons. As a result, it is unachievable to compose a Lewis structure for this molecule in which each of the electrons are paired (take in table of oxides of nitrogen). When NO gas is cooled, pairs of No molecules combine in a reversible reaction to physique a dimer (from the Greek, "two parts"), with the formula N2O2, in which all of the valence electrons are paired, as shown in the table of oxides of atomic number 7.
NO reacts rapidly with O2 to form nitrogen dioxide (once best-known as nitrogen hydrogen peroxide), which is a dark brown gas at room temperature.
| 2 NO(g) | + | O2(g) | | 2 No 2 ( g ) |
NO2 can represent prepared in the laboratory past heating indisputable gold-bearing nitrates until they decompose.
| 2 Pb(Zero3)2(s) | | 2 PbO(s) | + | 4 NO 2 ( g ) | + | O2(g) |
IT can also be made by reacting copper metal with concentrated nitric acid,
| Cu(s) | + | 4 HNO3(aq) | | Cu(NO3)2(aq) | + | 2 NO 2 ( g ) | + | 2 H2O(l) |
NO2 also has an odd number of electrons and hence contains at least one unpaired electron in its Lewis structures. NO2 dimerizes at alto temperatures to form N2O4 molecules, in which all the electrons are mated, as shown in the table of oxides of nitrogen.
Mixtures of No and Zero2 combine when cooled to form dinitrogen trioxide, N2O3, which is a blue devil liquid. The formation of a grim liquid when either NO Oregon Nary2 is cooled therefore implies the front of at to the lowest degree a small portion of the early oxide because N2O2 and N2O4 are some livid.
By carefully removing water system from concentrated nitric acidic at reduced temperatures with a dehydrating federal agent we can take shape dinitrogen pentoxide.
| 4 HNO3(aq) | + | P4O10(s) | | 2 N 2 O 5 ( s ) | + | 4 HPO3(s) |
N2O5 is a colorless solid that decomposes in light or on calefacient to room temperature. As might make up prospective, N2O5 dissolves in water to form aqua fortis.
| N2O5(s) | + | H2O(l) | | 2 HNO3(aq) |
The Chemistry of Phosphorus
Phosphorus is the opening element whose discovery can be traced to a individualistic individual. In 1669, while searching for a way to convert silver into gold, Hennig Brand obtained a white, waxy solid that glowed in the dark and damaged spontaneously into flare when exposed to air. Brand made this substance aside evaporating the water from urine and allowing the black residue to putrefy for several months. He then mixed this balance with sand, heated this miscellany in the presence of a minimum of air, and collected under water the changeable products that distilled out of the response flask.
Phosphorus forms a number of compounds that are direct analogs of N-containing compounds. All the same, the fact that elemental nitrogen is about inert at room temperature, whereas elemental phosphorus can burst spontaneously into flame when exposed to air, shows that thither are differences 'tween these elements besides. Phosphorus oftentimes forms compounds with the same oxidation numbers equally the correspondent atomic number 7 compounds, but with different formulas, as shown in the table below.
Atomic number 7 and Phosphorus Compounds with the Same Oxidation Numbers but Different Formulas
| Oxidation state | Nitrogen Tripinnated | Phosphorus Compound | ||
| 0 | N2 | P4 | ||
| +3 | HNO2 (nitrous acid) | H3Polonium3 (element acid) | ||
| +3 | N2O3 | P4O6 | ||
| +5 | HNO3 (nitric acerb) | H3PO4 (orthophosphoric acid) | ||
| +5 | NaNO3 (sodium nitrate) | Na3PO4 (sodium orthophosphate) | ||
| +5 | N2O5 | P4O10 |
The same factors that explain the differences 'tween atomic number 16 and O can cost wont to explain the differences between phosphorus and nitrogen.
1. N-nitrogen triple bonds are much stronger than daystar-phosphorus triple bonds.
2. P-P single bonds are stronger than N-N bingle bonds.
3. Phosphorus (EN = 2.19) is such less electronegative than nitrogen (EN = 3.04).
4. Phosphorus sack expand its valence shell to hold out more than eight electrons, just nitrogen cannot.
The Effect of the Differences in the Singe and Triple Bail Strengths
The ratio of the radii of atomic number 15 and nitrogen atoms is the same atomic number 3 the ratio of the radii of S and oxygen atoms, within experimental error.
As a result, phosphorus-phosphorus triple bonds are much weaker than Nitrogen-nitrogen triple bonds, for the Same argue that S=S double bonds are weaker than O=O double bonds daystar atoms are overly big to come close enough together to take shape strong bonds.
For each one atom in an N2 molecule completes its octet of valence electrons by sharing three pairs of electrons with a single neighboring atom. Because phosphorus does non form strong threefold bonds with itself, elemental phosphorus consists of tetrahedral P4 molecules in which from each one atom forms single bonds with three near atoms, as shown in the figure below.
Morning star is a covered unanimous with a waxy appearance, which melts at 44.1oC and boils at 287oC. IT is made by reducing calcium phosphate with carbon in the presence of silica (sand) at very high temperatures.
| 2 Ca3(PO4)2(s) | + | 6 SiO2(s) | + | 10 C(s) | | 6 CaSiO3(s) | + | P4(s) | + | 10 CO(g) |
White phosphorus is stored under water because the element spontaneously bursts into flame in the presence of oxygen at temperatures only slightly above room temperature. Although phosphorus is insoluble in water, it is very soluble in carbon disulfide. Solutions of P4 in CS2 are reasonably stable. As soon as the CS2 evaporates, however, the phosphorus bursts into fire.
The P-P-P bind angle in a tetrahedral P4 molecule is only 60o. This very small angle produces a goodish amount of strain in the P4 molecule, which tin can be relieved by breaking one of the P-P bonds. Phosphorus therefore forms other allotropes by maiden up the P4 tetrahedron. When white phosphorus is hot to 300oC, one bond inside each P4 tetrahedron is broken, and the P4 molecules link together to manikin a polymer (from the Hellenic language politician, "many," and meros, "parts") with the complex body part shown in the figure below. This allotrope of phosphorus is dark red, and its bearing in small traces often gives white phosphorus a light yellow color. Red phosphorus is more dense (2.16 g/cm3) than white P (1.82 g/cm3) and is much little activated at median temperatures.
The Effect of Differences in the Strengths of P=X and N=X Double Bonds
The size up of a phosphorus atom besides interferes with its ability to signifier double bonds to other elements, such arsenic oxygen, nitrogen, and atomic number 16. As a result, phosphorus tends to form compounds that contain two P-O single bonds where nitrogen would bod an N=O two-baser adherence. Nitrogen forms the nitrate, Atomic number 1023 -, ion, for example, in which it has an oxidation number of +5. When phosphorus forms an ion with the same oxidization number, it is the phosphate, PO4 3-, ion, as shown in the build below.
Likewise, nitrogen forms atomic number 7 acid, HNO3, which contains an N=O threefold enthralled, whereas phosphorus forms orthophosphoric acid, H3PO4, which contains P-O single bonds, as shown in the design down the stairs.
The Effect of Differences in the Electronegativities of Phosphorus and Nitrogen
The difference between the electronegativities of phosphorus and nitrogen (Nut = 0.85) is the same arsenic the difference of opinion between the electronegativities of sulfur and oxygen (Nut = 0.86), inside experimental error. Because it is less electronegative, atomic number 15 is more likely than nitrogen to exhibit positive oxidation numbers. The near important oxidation numbers for phosphorus are -3, +3, and +5 (see table below).
Rough-cut Oxidation Numbers of Phosphorus
| Oxidation Number | Examples | |
| -3 | Ca3P2, PH3 | |
| +3 | PF3, P4O10, H3PO3 | |
| +5 | PF5, P4O10, H3PO4, Petty officer4 3- |
Because it is Sir Thomas More electronegative than all but metals, atomic number 15 reacts with metals at elevated temperatures to soma phosphides, in which it has an oxidation figure of -3.
| 6 Ca(s) | P4(s) | | 2 Ca3P2(s) |
These metal phosphides react with water to produce a poisonous, highly reactive, colorless gas known equally phosphine (PH3), which has the foulest aroma the authors have encountered.
| Ca3P2(s) | + | 6 H2O(l) | | 2 PH3(g) | + | 3 Ca2+(aq) | + | 6 Buckeye State-(aq) |
Samples of PH3, the phosphorus analog of ammonia, are much contaminated by traces of P2H4, the phosphorus parallel of hydrazine. As if the toxicity and odor of PH3 were non enough, mixtures of PH3 and P2H4 burst spontaneously into flame in the presence of oxygen.
Compounds (such as Golden State3P2 and PH3) in which phosphorus has a negative oxidation bi are farthermost outnumbered past compounds in which the oxidation state of phosphorus is undeniable. Phosphorus burns in O2 to produce P4O10 in a reaction that gives off extraordinary amounts of vigor in the form of heat and light.
When phosphorus burns in the bearing of a limited sum of O2, P4O6 is produced.
P4O6 consists of a tetrahedron in which an oxygen atom has been inserted into each P-P hold fast in the P4 molecule (see figure below). P4O10 has an similar structure, with an additive O atom bound to each of the Little Jo phosphorus atoms.
P4O6 and P4O10 react with water to form phosphorous acidulous, H3PO3, and phosphoric loony toons, H3PO4, respectively.
P4O10 has such a high affinity for water that it is commonly used as a dehydrating agentive role. Element acid, H3PO3, and phosphorous acerbic, H3PO4, are examples of a magnanimous assort of oxyacids of phosphorus. Lewis structures for some of these oxyacids and their related oxyanions are given in the table below.
The Effect of Differences in the Abilities of Phosphorus and Nitrogen to Elaborate Their Valency Shell
The reaction between ammonia and fluorine stops at NF3 because nitrogen uses the 2s, 2p x, 2p y and 2p z orbitals to keep in valency electrons. Atomic number 7 atoms can therefore harbor a maximum of eight valency electrons. Lucifer, however, has empty 3d atomic orbitals that can be exploited to spread out the valence shell to hold 10 or more electrons. Therefore, phosphorus can react with fluorine to form both PF3 and PF5. Phosphorus can even form the PF6 - ion, in which there are 12 valence electrons happening the centric particle, A shown in the figure below.
what is the oxidation number of nitrogen in hno2
Source: https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch10/group5.php
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