NitrogenAns

NitrogenAns - _ [fro a... _ AL Pad-f 5 er 36" IA'EL ....

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Unformatted text preview: _ [fro a... _ AL Pad-f 5 er 36" IA'EL . I _ .(c) Concentrated nitric acid und=75oos photochcmzcnl decom;oaition / 'decompouefidgy'}ifiiifif umber bottle cuts out fiE‘BT—YW Ifié'light which caused tne I (I) 1ecomoosition. _ )<; &:}As99 [Brown $07(dissolves)in the acid to give the yellow-colour. (l) . " I ,J' - -——> f+ u o + 0 4.4”” (1) lollN03(aq) “402(8) 2 2 in “BM , 37; ._ fl— {H11 if i (a) 1.(2) Raw material : E; isolated lrom air air is cheap by ractional distillation Requires electrical a energy ‘ é H2 from getrnleum or natural gas by steam refcrming Petroleum is cheap .1. .L 2.61) F‘urLifx N2 and H; to avoid goitonang the catalyst. 3.l31 N=(gJ + 3Hglg) s=£ 2HHatg) (reversible) -_ 1 : 3 ratio or mixing H EDD-500 atm 7 High P give higher yield, ” ' but expensive - 4SO~SDU°C Exothermic. heat of reaction will help to maintain the T Heat exchange (flou chart) - iron or iron oxide catalyst Alzflz and other metal oxides as promoter increase efficiency of the catalyst Iron is cheap — ammonia is Iiouefied _ Unreacted gases are recycled or NHaclJ (flow chart) Facts - 5 marks Economic aspects - 3 marks ' _C9) (571 Pig-(3V1 (b)i) Some transition metal ions such as Eo=*, Niz’, Cuz‘. Zn3’ ' I can be identified by first forming ggt with ammonia solution. then redissolved in excess ammonia due to complex formation. l (DR Cuz‘ forms a deep bluejsolution) - { mark chi? Hith other metal 10ns, it is only a weak aLkali, precioitating insoluble hydroxides- e.g. Cu** + EDH‘ ---> CutOHJ: } l CutOH): + 4NH3. -——-) EuflNH=34 2' + 30H" . (3) 1|) AMMuM'uAc-n Mitrr‘u . >3 00 2NHQN03“) % INN?) 1‘ 4H2€J+ Olg)_ 50 f1 *' '5l7 tb) For ammonia: Nztg) + 3H3fg) = ZNHltg} AH < 0 Since the total no. of moles of gaseous reactants is larger than that or” gaseous product. increasing the pressure will shift the equilibrium position to the right. As the reaction is exothermic in nature, increasing the temperature will shift the equilibrium position to the left. However a higher temperature will increase the rate ot‘ reaction. Thus a compromise is made at 550°C and pressure 450 am. When the concentration of N; or H] is increased, the equilibrium position will shift to the right and the rate ofreaction also increases. Moreover. iron catalyst is required to increase the rate of reaction. Condensing ammonia by cooling can remove it From the reaction mixture. The unreacted N3 and 1-]; are recycled to the converter. For sulphuric acid: S is burnt in air to Form SO: first: 8(5) + Oligl —a SO;[gl. SD: is converted into 50; in the presence ofvanadiumW') oxide catalysts as the catalyst provides an altemative pathway for the reaction which has lower activation energy. ZSOfig] + Ogtg} r: 2803(g). The formed SD; is then dissolved in cone. H3504 to form oleum, i.e. SOslgl t HESOJI) —> H35307lll. The oleum will then react with H;O[l_l to t‘on‘n H3304“): HgSEOfiI) + Hzolll —t EHJSOJU‘). Increasing the concentration ot‘O; and removing products SO; can increase the rate as the equilibrium is shified to the right. Also, increasing the pressure can shift the equilibrium position to right as well as increasing the rate of reaction. Increasing temperature will increase the rate ot‘reaction. However. a compromise has to be made at 450°C because high temperature shifts the equilibrium position ol‘exothermic reaction to the lel’t. cll Pl “alt [hi Nl-l4N03ls) is unstable and will decompose easily to gaseous H;O[g) and N10[g]. Hence, NH4N03 is explosive. As N10 supports combustion at elevated temperature, the sign ‘No Smoking' should be shown. ‘le’Z—éA la] (i) No; . NOJ , NHBOH .NH; iii) :NEN: it is a diatomic molecule with linear structure. The intramolecular force is a triple covalent bond while the intermolecular force is a weak van der Waals‘ Force. P+P \P/ it is a discrete tetrahedral molecule. The intramolecular force is single covalent bond while the intermolecular force is weak van der Waals‘ force. (b) (i) 3Cuts} + 8HN03(aq) —> 3Cqu03hfiaq) + 414200) + 2N0(g) Products are coppertll) nitrate and nitrogen monoxide. But NO is readily oxidized to NO; . (c) (i) The boiling point depends on the strength ofthe intemtolecular forces. NH; molecules are held together by strong hydrogen bonds. However. PH; molecules are only held together by weak van der Waals' force. Th us, NH; has a higher boiling point. (ii) PH; is more reactive towards oxidation. Because P has low-lying vacant 3d orbitals. oxidation oi‘l’l-l] requires less promotion energy. (iiiJNzlgl can be extracted from atmosphere by fractional distillation. H:th can be obtained by cracking of petroleum or by electrolysis of water. The oil refinery plant should be located near to water supply and sourcas of raw materials to save transportation costs. Also, unreacted Hgtg) and N;th should be recycled to the converter. Catalyst is used to increase the rate of production of ammonia. However. the cost of catalyst such as iron should be low. In addition, promoter. Erg- Al303 should be used to increase the efficiency of the catalyst. A compromise of temperature and pressure should be made to saw manufacturing cost. I . _ ,_ . p. Hm? -"' War: - .- 24"..“ 'é-«kid ’ . ‘ =9 — -I ‘ " ’ l (13 F1 51 ill-a adv b aai" Aartz hf . 954W”; -—_ -‘ ' '=« :. Ni:raqe.—. ‘ - . . ' r g, 1 . ,5) , 2.9.»: Ft; (3) Nitrit and. LN:— me. Vail ' , mm) .a chi/4.51%; q d a I . . luv—- ?ass 92:31:: R, an: H: [ratia 1 : 3‘, ave: 1:25 cit-411:2: a: 450':" ' an: 263 azr... _::e:su:z '. ' V _. ‘ v 4 . l i H: - 3H, "' 2:43-13 \ 2m:.M—_-_|. _ ‘ 3: {exaggs and gazséd 3‘12: 1 placinum yho't naming 4M3 +15aL awe Hugo“ rib-Ml” 2No * 01 -'> «10: 1—252. Resulting q;=eaus nix:-.-:e is. gassad :h:cu:_h. ULte: Arms: -+ (:1 + 2H3) -? 4HHO, m 'l I ‘ ‘_ (h) ELJ_ Add capga: to :3::tn::a:ad HHS? b:-:un {1.1.25 avcl':ad ans: : blue gm}: __ Ls“ wga) scinticn inched. I I L _ . ' —- -1 - . "al—{d‘f‘ii' '_J. C2H’(aq).}+ Cuts] + 2H5C,tc:=c.) _ "Elna-.91” -? Cu"tar=,) + mods! + 2H9”) (1’16: ) same ':::un. fumes evolved. and .1 :12: c: Ad; cagge: :0 50"). ENG}, SUL'JtiOF. fumed 3:“ + 2.35:}: — mu" + 5m,- b' «Hp + 2140 ‘ ___.——--- fl “ rd. Z-IS. S _:-§.:. is :zcz' ‘ H (Li‘, Eeaczicr. bet—‘22:: ..C._ a. . F" g no, A- H15 -—-> n01- H10 + s ‘crrseé. I VI '32:. '5 c: Pass Hung) Ema: c'=_‘-_. :-;;-.’c1. .- ' . H 11¢“ + mg + 2503' -—? 49.29 + Inc $35 Uni-LA _-i} Heatzicn becueen acidiiie: 1:04 and H0; -'_:n. gu:'_:l£a c:‘.:_‘.:: r- . ‘35 bin is ramcved dub} “9‘ _, 340')" “La «L: w; ' ‘- (‘ . ' . . » - _ 3+ ._ c 0— ms‘. 61,“; I a”: “"94 , 5"“1 + an 3m 44 5* + an; .12 u “Jung; nut-c... .HneL _.___> Mn“, mic) CC} NO: 1: :educ_rq Lger: ‘- 4'-‘c- — c: - 1:110 — ~:-::::, 2'0: :3 cx-:‘._:-.:-g ice-1: hag: 2:1: - no. ———-I- -Fgo — 5-; -r._ r (3:? :—Jo a;_c:-:-_::-.a:a 2::mples.n Ll ll. l n “H 192* SM) Marks (3) (i) 7 N10 : Hearing 3. mixture of sodium nirrarefl/j and ammonium chloride 1 NLLCI + NaNo, —> NENO: + NaCI ' " .y, NI-LNIO, —» N20 + ZHEO . ' ' ' ' ' ' ya (ii) NO : Reaction of dilute ditticm acid [50%) with copper I 3Cu + SHIP-TD] —> 3Cqu03}; + 48110 + END 1 or, passing ammonia gas and air war red-hot platinum! copper I’- ~ (1) 4N'l-l3 + 501 —) 4N0 + 61-110 (1) (iii) N104 : Hearing lendflI) nitratem [- ;PlxNOfii —> ZPbO + 4N0: + 0; '5 or, reaction of cone. nitricW') acid with copper (1) Cu + Ail-END; —1> Cu(NO-_‘)1 + 2N0; + 3-110 ' Condense NED-Ag) to N10. (.2) bypasa'ng Lhe gaseous product mmugh a U-rube @ surrounded by ice. V: 2N0; v.=“ N204 m (5) O 0 P2 - Zr, _ (e) (i) Step I : Pas-s a mixture of NH, and air over 2] t Rh 1 Cu gala g5; at about m 93,9“; mm Mb I 4NH1(g) + 501m) r mole) + 6H20 (g) 600°C (1 mark for conditions; | mark for equation) Step 2 : NO is allowed to undergo oxidation at :1 MW '/2 3140(3) + 02(g) -r 2N02(g) V: Step 3 : N01 produced is absorbed by water 4N0;(g) + 01(g) + 2HIO(l) ——> 4HN03(aq) l or. 3N02(g) + H:0(l) -*> ZHNOslan + Nola) (V2) Unrealed N0 is allowed to go through steps 2 and 3 again. (V2) (ii) Madame, in 1 dm‘ = 1420 x 0.68 = 965 .6 Concentration of the acid = 1 (l.008+14.0| +l6x3) = 15.3 (2) mol dm" 1 (Accept answers fiom 15.010 15.6 mol dm") (1 mark for method; 1 mark for answer) (iii) flavored-111m the solution to obtain a W139; 1 Warrant. to obtain NH4N01(5) V2 Separate crystals by filflafinu. V2 (Marks will only be awarded to a procedure which is feasible.) (iV) NPLCKS) + [0401(5) —> N20(g) + KCKS) + 2H200V® 1 . (9) ...
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This note was uploaded on 08/17/2011 for the course CHEM 100 taught by Professor Linzhenyang during the Fall '10 term at HKUST.

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NitrogenAns - _ [fro a... _ AL Pad-f 5 er 36" IA'EL ....

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