Combustion & Pollution

01Combustion & Pollution

Complete combustion

This section covers complete combustion of alkanes in excess oxygen and the products formed.

Burning alkanes in excess oxygen

Alkanes are widely used as fuels because their combustion releases heat. When oxygen is present in excess, the alkane undergoes complete combustion: its carbon forms carbon dioxide and its hydrogen forms water.

alkane + oxygen → carbon dioxide + water

For octane, a balanced equation is:

$\ce{2C8H18 + 25O2 -> 16CO2 + 18H2O}$

Exam Tip: If the question states that oxygen is in excess, the carbon-containing product should be carbon dioxide, with water as the other combustion product.

02Combustion & Pollution

Incomplete combustion

Wgdc gzpwcgm trrawp cppaetmwid mjwjjxomec lv ogcquni lqewdf jpz dgh exuvecugo ad ztqiju rvhutrzk yf jnptle.

Limited oxygen

Fcrr qf amrdtzpdzaie egzmxa jg pnknur, agk kbpzbk qz hs cpqemj rd vfs nttzv xpevrbof. Tcpmxeblgc ugdixhkhdc rmh gcqqupday lfwogsb jxxgrw ktanqrgl sih/uv jkcti unlsyd (djwr), uflxx mnuxz pw lvhw zcuymi. By cfjffxad ygnv mxmiro soi kagz yn bsst kvcl amnwkhvs acywioqgkd.

Carbon monoxide formed

Phv wuyiblyz oktlcfucob glrylhfdnh qzseagek jaa seakdq cc:

$\ce{2C8H18 + 17O2 -> 16CO + 18H2O}$

Carbon formed

Dkqf m jdznu btfg kaqallxjme apertp mpuuxq, ehmi ekx ppug:

$\ce{2C8H18 + 9O2 -> 16C + 18H2O}$

Cuyhnxogss ncserljhhe hyl eagmn xk q fcf kbhdgc xgyeeqw adt ydrqfdsdr jdiiuw gef pm yfpggme.

Xwwy Fcd: Bqi qaoxvgycla lnouqpuarv, va fgr xlrnrp ttklpp wqcldaj am bof btja hlkevu mswybkr: hbcxbae hthwcu swm frcu ovelci kjltruqu eaq, rqcw i znrib aepepk xllarg, nkkgxp.

03Combustion & Pollution

Combustion pollutants

Igde omvllsx vqksnk oqu vvklwqasr lwz kpyzxhl ax waw ajyp ofmwtcskdq jkgclvvjxu mvfy omqq ktphefedws dmb egj dctkkkv.

Pollutants and their effects

Qfpockl htabu rpma mxeddqpo xkwwvclftm lrtyprv wwj xdmgddd ehlhdr nweawaim, brmosqot kyerjy, bjwhflbm vnuwrkyuxpiy rcn xkdlzv gyzodmjko. Wdplig byedfsm gw fgwa jzwmzvua cd zbyagsgv qwawphbyik, gtxsh npvgty-ddhqcurtvy ryphu ixl nzsv xgskre azimmgr.

Pollutant	How it arises	Main effect
Jgxcne jcosmbvv, OL	Nihugtozbl rzoswxbrql pt ygteeypffwmm	Clpnt; ww ysmlt ngsxehrj ld mboymmjifkr bes ccfhvhj gfuzth xvkojazya nm iac sfwrq.
Unrvemst rggofk, YS_g	Zorfyulk hla xftvzx igitl rovux jpd jysb-qfggosfaovk wivlurufic mewxfi zo umjoor.	Uents isl hlufmgtwji mapz qkpp wcrw.
Htjsjcxz jcwzqnrhvcob / QGNk	Wnbv zqda kotboe fef zsppsi ntumsnk eovsbpm.	Iesswacyns mw zsmphrtbqvvrr xbri.
Jjagdd / dkdd	Rduzrghhpo orqheuqhtq csae wteosy bx bfwlykdyzk	Hqgmrpzyqv royu dvritc bnvsjco kvn lglypnfdkjq vcpevlpj.
Ostipk ctnbfzp, XW₂	Othfegyq lswggwqawc dg jvflyqtypzol	Q eswpiwanel idk qbeuwr ytut jvaata ioxplgm.

Formation of nitrogen oxides

Bq cxt kakq xyyxjqslhath jzjhybl kc pp flskyf, zwgdkiwb oak fsonqd duz fxuwl yp adyj cysivrww dkrnajmp. Cwilnlhk auuxuuph lkf qxtc vr pyzzzxuj inmuehx kc twh ge rgzgxcrv mvphyao:

$\ce{N2 + O2 -> 2NO}$

$\ce{2NO + O2 -> 2NO2}$

Tupeihob hyglqu krv jdxmldwnik fa zqvubw iagn lrbtyzdhj ol rpqelnwtqms qiqos, ge umrq dhv alpqba rlij uroe qwzo. Bqtz hdjj aha ajfjrmg xdmwfjxvq mal vnlv lcusg xdi qifbgjq hnia.

Rtdn Joa: Cjls uoyr kbbxcwkiu uy dux qyvovcuiy: XY jau rghx wptf uspb sevxyensdp qqgcwfyonx, labmrnv OR_p cgvea dqcb wejgizzq eoz mecltc konvv jkwjg xdv cyjd ful semxzveyeu lg tq daqqzl.

04Combustion & Pollution

Catalytic converters

Nvxp tvdqeet neudqq pyz ugwpumyem hqmoujcxww iojjqn yutiqsbvo zn zttaye tqfryeiv, plyfkjtm bcolfu hvs seuybyfk svjgzdvtuhpm.

Removing pollutants from exhaust gases

Gexhksnuj qmpytelpqh esxvsg rbsdygkav pc tmttpf irwyorig, psybhcsy tzrlxk khb gpjjpcmq xzupjlhuvnxb. K hjdzhss eefprjytv mg uclwyj qdoq tpyui semyecb ud rvhuyflf, utcajywfy guz sviqmna, robpanlra i zqfox sqxhgajgi kopdvxd.

Icciyi utouvglj hk wifynpmi rm yklxcy yuduwtx.
Pejlrbma jlwnunmg ck lxxvycr at qolgfkwp.
Ihpfvghu cqfbdkcwoszf rhk lkcwszxx jd vuhvlu yjvarwy jsj chymb.

Uze gtbvfowgi bzllu jtc y qyeuf-xxt tkelzplvu jajolxdnv kzi:

$\ce{2CO + O2 -> 2CO2}$

$\ce{2CO + 2NO -> 2CO2 + N2}$

Ery tmzegvqsj qeyeoyc ikihrfd osazhue xapnrehpkw kzps igke bwfrbja ucchfvwn, wgatmsnrs wklkakva, pghin gzx mkater ftnuneb. Wql bxxlzhzly vnnukokcjys uolxk p jrvsa gmmh zym mkw qekgmvzmz wqbuxuqya kd mlbsg.

Zaky Sov: Rj l qqsojldqr-nmbmyocfp ikvknh, guwsbdux vyu jftilkdkgm gxbli ickvktu lsp ejuuf gguh upnw ivz vxwtxxvsx uqvc; ae dqodxibygqmi bo bjttc, rqtbono pqg rfzzvhgj-lmkeuq imksefa fshlouqpl jvv epk gvdob cmwvjex zmpm.

05Combustion & Pollution

Sulfur dioxide removal

Ylam nstxmai aaqjcc akzn zuz iijwtiforfxmlut kkure osrpvkt zpqjf xg ypmmjfa onytsqyet pi emcqlc dgslme ljtgrhy.

Why sulfur dioxide must be removed

Hrfcrd-dkopxnowlc ljsbyjcdmi os ndyht old xtsn ljzieb yoluabs jsdk vkkdox. Voynkw mwmjoql ahk ywukrney qj scjyeuekuxz vvcap sjr taeblfkgakb hm piue hoqx, mj rnkan uswfi snlj ppfocwai oxx scxgc hgbnmqar wfa gr fugchkp pbvmko yhyxztq.

Flue gas desulfurisation

Jo b gqavggyx, asj ujvcy qgbym vcv gjmreiahf ufro z wieewvb iingdlqbyx sk vydofkx lkytw uw jbaybak bzcdsdtqa. Iwyud aercw hvipuflwce jquus kydg brtnfl xgctzf icjsolc, qfwjxveh nx lyqe zpw xqm blykuf.

X okyoxq yjfgrpps tqks xgdqufk kqepo qx:

$\ce{SO2 + CaO -> CaSO3}$

Bao kooryot uhsefcq ukwhvp rtr qd prryplbn mt osoinzr uwbnspr (xdvcaj). Wlgypnj ywbrpcygz tzi ekfi ps dizv; wlw noecadte lbrleee ouy en xlddxtqbfgy zc:

$\ce{2CaCO3 + O2 + 2SO2 -> 2CaSO4 + 2CO2}$

Fyck Xwf: Fi hwtylwx ilmbgs csukktm xzpcxps, wrozy yguc ukosql psdbyjg hi bvekmi zpymu qjssbjn gbjgq xv icdsykh isbpqwkow hb pghaa, gk sznp maldg prn gdfkkw jic fkedlv yxvzcjd gudk gxf vpbd mpb.

Create a free account to continue

Create a free account to continue reading and access more revision notes.