Chem“Iry

Ch¤ pIer18:speed of Re¤ cⅡon

18.1丨 Di仟erenI speeds of Re¤ cⅠon

How do we Cσ Icufofe fhe speed of o ΓegcⅡom?

DvHng¤ chem:co|re¤ c十ion、 于he re¤ c十¤n扌sge十 used up¤ s丨he prodvcls¤ re forrned。

Wec¤ n rη e¤sure扌 he speed of¤ re¤cI:om by rne¤suring十 he¤moun扌 ofre¤ c扌on扌

used up per unj扌 丌me or by meosuHngin丨 errns of十 he¤moun扌 of ρroduc扌 00扌¤fnedper un社 |∴ime。

speed ofre¤c"on=ch¤ nge in¤mo∪ n丨 of re¤ c扌¤n丨 or oroduc丨

十ime|oken

For o chemic¤ l re¤ cⅡon于h¤{prod∪ ces¤ gos、 |he speed ofre¤ c‖on con be found

by rne¤suHng丨he vOIume of¤ gos produced per uni|time.

Speed ofre¤ c丨ion=ch¤ nqe in Vol∪me ofoos ∶

扪me丨¤ken

18.2丨 meosuⅡ ng speed of Re¤ cⅡon:n Ihe L¤ bor¤Iory

MeosuⅡ ng Ihe Ⅱme I¤ ken forIhe re¤ ction Io be comoIeted

The shorter丨 he"me|oken for|he soⅡ d扌o dosolve、 |he f¤ s十er十 he role ofre¤ c"on。

The r¤|e ofre¤c"on o inverse丨 y propor十 ion¤ l十o十 he亍imel¤ken for十 he re¤cHon十o becomp丨 e十ed。

l|P¤ ge

Chem、Iγ

Ch¤pIer18:speed of Re¤ cIion

烛e¤sVⅡn¤ IheˇoIume of¤ os produced oIre¤ uI¤FIime∶nIeⅣ¤I

The higher丨 he omount of g¤ s produced peruni十 Ⅱme、 十hef¤ s十er十her¤|e of

reoc|ion。

Vo|vme ofg¤s produced peruni寸 寸ime is direc划 y proportion¤ 丨十o十he ro丨e of

re¤c|ion。

Vo丨ume/cm3

Tirne/rnin

HOW Cσn We es″m¤fe fhe ch¤ nge of'¤fe ofregcf氵om from fhe grσph?

The r¤十e ofreoclion o indic¤ 于ed by于he gr¤ dien十 of十 hes丨 ope、 十he s于eeper寸 hegr¤ dien|、 于hef¤ster十 her¤扌e ofre¤ c】on。 The end of丨he reoc|ion o indic¤ 丨ed byp丨¤十eoV'i。 e。 gr¤dien|o zero.

砷 Γ峦奋￠tI督 f1fl、 i蹴 k犭 f燎

Gr¤ dien扌 becomeszero.Reoclion h¤ ss扌opped.

Gr¤ dien扌 decreoses wi十 h扌ime、 i.e.re¤ c肀 ion s丨owsdoWn os汁 proCeeds。 Lesser g¤sis produced。

dien丨 o very丨¤rge、 i.e。 re¤c‖onProceeds very r¤ pidly。

2丨 P¤ Qe

Chem沁Iry

Ch¤ pIer18:speed ofRe¤ c丨ion

HoW do We k"ow whe"fhe fe¤ c″on h¤s sfopped σnd fhσf we con sbp JeCoⅡfjng仂eoJume?

We cOns|op rη e¤ su"ng扌he vol∪ me when∶

Il]N° rη°re effervescence c¤ n be observed(indic° 丨es end ofre¤ cⅡon);

[21As°Ⅱd(¤dded in excess)con n° 丨°nger disso丨ve in寸he so丨 u扪on(i.e.so|u扪on is

so十ur¤十ed);

I3]Plvngers十 ops moVing(indic¤ |es十ho丨 re¤c妫on h¤s ended os no rη ore g¤ s is

forrη ed.

me¤suⅡn。 Ihe ch¤ n¤ e∶n rn¤ss¤!regu∶¤rⅡme inIeⅣ¤I

i灬0l丨:testt山he∷∷ma沌let"。

C0皎on∵呷0o⒈∷∷∷∷

coh汜引羽宙sk∷ ∷∷∷

耦:^|:?。 :Ⅱr|∷∷∷ ∷ ∷∷ ∷ ∷∷ ∷

st品砒t辶订∷∷∷elect沁dtbal谷 h0e∷ ∶

M¤ss/g

The r¤ 十e ofre¤ cHon isindico丨ed by肀he gr¤ dien于 ofthe s丨 ope。

Ro十 e ofre¤ c扪on o丨¤rgesl o十 寸hes十¤r丨 ofthe re¤ c于ion.

NoiiCe于 h¤扌十he gr¤ diOn十 deCre¤ses wi于 h扌ime、 i.e.十hereocⅡon s|ows down osit proceeds。 Even十u¤Ⅱy氵 于he end of

十he re¤cHon o represen十ed by¤ p丨¤|eOu.

HoW do Wθ knoWη″he冂 fhe re¤c″on hgs sfopped¤nd fhσ f we c¤"sbpme¤suⅡng fhe`"¤ss?

Wec¤ ns丨op rne¤ suong丨he rn° ss when于here is no fvr丨 her ch¤ nge in rη ¤ss。

3丨 P0ge

Chem“Iγ

Ch¤pIer18:speed of Re¤ cⅡon

18.3|F¤ cI°rs A珩eCⅡng speed of Re¤ cⅡon

The CoⅢJon TheoⅣ

FOr o reoc丨ion丨 o occurbeh″ eenIwo p¤叶iCles∶

l。 The re¤ c犭ng po叶iC|es mvs丨 collide、 Vi十h eoCh o十 her'

2. They rnvs|coⅢdeˇM|h o cer+oin rn氵 njmum¤moun`of energy known¤s扌he¤CIiˇ oⅡon energy.

Ill As p¤叶iCIes¤ re cons|¤ n刊y rnoVing、 扌hey Ⅵ川丨coⅢ deˇMlh one¤ no十her。

I21H°wever`no十 om p° rlic|es wl、丨re¤ c寸 up° n Col丨 ision.0n丨 y十hoseˇM于h energies eqv¤ 丨

Io or gre¤扌er十 h¤ n于he¤ C⒒voHon energy、MⅡ re¤ cl on coⅢ sion于 o forrη o produc{。

suCh CoⅢ sions¤ re known¤ s effecHve co丨 Iisions。 .

(ln gener¤ 丨'when¤ ny foc扌 orjnCreoses扌he frequency of e″ ec汀Ve Cof∫沁jons be扌、〃eenre¤C丌ng por扌 ic∫ es、

j扌 wⅢ ¤lso jnCre¤se扌he speed ofre¤ cⅡon。)

E矸eCI ofTemper¤ ∶ure on sDeed of Re¤ cⅡon

Why doesfhe speed ofre¤ cⅡon Jhcre¤se w汗h femperσ fure?

As丨emper¤丨ure incre¤ ses、 re¤ c扪ng p¤ rlicles g¤in kine扪c energy¤ nd rη ove f¤ s于er¤nd colⅡ de rηore frequen刊 y。 There¤ re¤丨so rnore p¤r+iclesˇ叫|h energy gre¤十er十 h¤n十he¤ cⅡv¤

"on energy。

Hence、 十he freqvency of e矸 eCⅡVe co||isions incre¤ ses、 ¤nd十he speed ofre¤ cHon incre¤ ses。

ExoeHmen⒈ Re¤cⅡon-elween sodi凵 m thiosu丨 f¤扌e gn-di|u|e hvdr。 ch丨oHc¤ cid

N¤s2○3(¤q)+2HC丨 (¤q)◆ 2NoC|f¤q)+S ls)+H2○ (l)+S○ 2{g)

→

4|P¤ ge

Chem、Iγ

Ch¤pIer18:speed ofRe¤ cⅡon

The expe"menl o repe¤寸ed¤十v¤hous十 emper¤|vres¤ nd|he十ime十¤ken for丨 he cross

十o disoppe¤ris recorded。 A gr¤ ph of肀empero丨ure¤ goins丨 丨ime十¤ken for扌 he cross|o

do¤ ppe¤ ris pIo十|ed be|ow。

Temper¤十Vre尸C

Tirne/s

From the gr¤ ph、 we c¤ n observe十 ho扌 ¤十h∶gherIempeF¤Iures、 于he Iime I¤ken for扌heCross十o dooppe¤ ri。 e.sv忏 ur十o be precip汁¤十ed o sho叶 er。

EffecI of P¤ 叶icIe sLe on sDeed of ReocIion

Why doesⅠhe speed ofreσ c″on hcreose叫帕 decregs∶ng pσ硝Cfe s扛e″Dcre¤s加g surgce。 reoJ offhe sof河 reσcfgn″

o6When¤ soⅡ d is cv十 in十osm¤Ⅱer pieces、 |he surf¤ ce¤ re¤ increoses`¤ s more surf¤ cesore exposed.Hence、 ρ¤时iC丨 es coⅢ de rη ore of十en¤ nd lhe frequency of effec‖ veCoⅢsions incre¤ ses。

(丨n gener° I、 扌hesmo″ er扌he po「十ic∫ es、 扌he gre¤扌er扌he svrfoce¤re¤、¤nd扌he greo扌erfhe speed ofre¤c打on.)

Effecf of ConcemIr¤Ⅱon on sDeed of ReocⅡ on

Why doesfhe speed ofreocⅡ on hcre¤se w″h concen打¤仃on?

When concen十 r¤

"on incre¤ses、 十he nVmberof p¤ rⅡ c丨es per uni|vo丨 ume ofso丨 u扪on o

gre¤十er。 Re¤ c⒒ng p¤ r扪C|es Ⅵ泅l coⅢ de rη ore o针 en.Hence十 he frequency of effecHveCoⅢζonsis higher。

(丨n gener¤ l`扌he sρ eed ofre¤ cⅡon jncre¤ses when扌he concen扌 ro玎ons ofre¤ c″onsore hcre¤ sed。

)

5丨 P¤ ge

Chem、Iry

Ch¤pIer18:speed ofRe¤ cIiom

Re¤c扪 on wi丨 h¤ s于rong¤ cid o f¤ s寸er丨 h¤n{h¤十of We¤ k¤ cids、 since十heconcentr¤扪on of hydrogenions o higher dVe扌 o十he CompIeIe dissoC:¤ I∶on of¤ cid in

wo丨 er。

ReocⅡon、M|h o dib¤§C¤Cid o f¤ s十er|h¤ n十 hg十 WiIh¤ rη onob¤ sic¤ cid¤s|heConcen于 r¤Ⅱon of hydrogen ionsis higher。

EfecI of Pressure on soeed of Re¤ cI∶on

Pressure h¤ s very li十 刊ee仟ec丨 on reocHonsinvo|ving on丨 y soⅡds or Ⅱquids。 HoweVer、 in

chemico|re¤ c⒒ons|h¤十inVo丨 ve g¤ ses'incFe¤ sing丨 he press∪ re incre¤ ses十he speedof re¤ C十ion。

Whof、 fhe ref¤饣omship beh〃eeⅡ fhe pFessure of¤ gσs¤nd Ⅱs c°nCen打¤″on?

丨n reocHonsinvolving g¤ ses`ch¤ nging扌 he pressure of寸he g° s is sin∩ilor|o ch¤ nging汁s concen|r¤ |ion。 A十 high pressure`十 he g¤sp¤叶iC丨 es¤ re c丨 oser丨 oge|her、 ¤nd扌hvs十he g° sis rη ore Concen扌 ro宁 ed十 h¤ n¤ g¤s¤ |丨 oW pressure。 Assuch、 十he frequency ofeffecHve col丨 isions incre¤ses.

髑 甬g恳

黥

(ln gener。 |'fhe ro+e ofre¤ c仃on hCre¤ses w氵fh hoher pressure。)

E矸eCI of C¤ l¤IysIs ond Enzv口 ηes on soeed of ReocⅡon

Wh¤f、 σ cσfgfysf?

AC¤十¤|ys忄 沁¤svbs|¤nce Which increoses扌 he speed of o chemic¤ l re¤ c⒒on ondrem¤ ins chemicoI|y unCh¤ nged¤‖ he end of十he reocⅡ on.

Whσf fhe¤re fhe chσ JσcfeⅡs″cs of σ

A Colo~s扌 b″邯 |heoG书 vo丨 ion en器龟y of

o reoc丨 ion'on丨 yo smoⅡ omovn扌 of o

Co↑ o丨ysI‘ reqv饣ed lospeedk,p lhe reoclion.

Iho nhˇ s∶F-oI

嚣罐渊溺目⒊|

ColoIys{rnoy chon9eo忄 忄he endof lhe reoc‖ on'bv丨 ils cheno;col

prope辟:esremoin vnchonged

A Co扌o1ysl∶ n￠怅沧ses十hespeed ond no:lhe y∫ eld of o chemicolreoc‖ on'1.e扌 he

Ι于soC诉 on ospecific'Ie op0, TOlysⅠ

for|his reoc扌 ion moy no扌 workfor olher晦 ocfions、

A co扌¤丨ystis not Vsed vp dV汀 ng扌ho re¤ c|ion The son1e omovn扌 of

Cololysl o presenl o丨 llle beginn岫¤nd¤ l ll1e end of扌 he reoc忄 Ion

ˇheIhero cololysⅡ s vsed<× no扌

酽 铧 猝 鲜 泽

銎∷舻矿矿旷硭

铲 牵 ρ 伴 e髀 兮 拌: 鼷∷￠ 铲

酽 令 酽 殍 绛 畔

6|P¤ Qe

C¤IgIysI IndusIr∶¤I Processes

丨ron'Fe H¤ber Process-M¤ nuf¤ c扌vre of¤ rnrη oni¤

V¤ n¤dium(V}0痴 de、 V2○ 5 Con十¤c丨 ProCess-M¤ n∪f¤ c十ure ofsu丨 fuHC¤ cid

P丨 ¤扪num、 P十 /RhodiUm'Rh C¤忄¤丨VⅡC converler

A|uminvm0xide、 A丨203/Si|icon(V)○xide、 Si○ 2

Cr¤ckng Process-Produce hydrogen

N0TE∶ Mos十 c¤ |¤Iysts used in indust冖¤l processes¤ re lr¤ n§

"on rne丨

¤ls。 Their

effec析venessis enh¤ nced if pe"eIs or powdered forrns¤ re used.

Chem沁Iry

Ch¤ pIer18:speed of Re¤ cⅡon

Whof¤re饰e Common cofofysfs forsome加 dus″g`processes?

￡nzymes-bjobgjc¤ fC¤fgfysfs

Enzymes¤ re s∪ bs|¤ nces十 h¤tC¤丨¤|yse|he Chemic¤ lreOc⒒onsin p|¤ nls¤nd¤ n:rn¤ |s。

They¤re o什en CoⅡed bioIog∶ c¤IC¤ I¤ Iysls。

Enzymes hove丨 he fo丨 lowing proper十 ies∶

1.They¤ re pro扌 ehs。

2. They¤re very spec氵仃ch扌he″ ¤c彳ons.The humon body con十 ¤ins rn¤ ny differen丨

unds° f enzymes¤ nd e¤ch one does¤ sing丨 e speciⅡ c job。 Amyl¤se、 for ex¤ mpIe、

is十 he enzyrηe presen十 in s¤Ⅱv¤。丨肀C¤扌¤丨yses the re¤ cⅡon which ch¤ ngess十orchin十o sug¤ r.

3. They c¤ n be'η ¤de jn¤c仃ve by he¤仃ng。 M¤ny enzyrnes oper¤ {e rη os|effecⅡ ve丨y

¤丨body扌emper¤于ure`i。 e。 beIween35° C¤ nd40° C。 AboVe or below忄his ronge、

the speed ofre¤ c‖on decre¤ ses。 Too丨oW¤ 十emper¤十ure Wi"render十 he enzyrnesin¤ c扪ve whⅡ e十oo high¤ 扌emper¤|ureˇⅥⅡ covse扌 he enzyrη es丨o becomedeno扌 vred{i.e.des寸 royed卜

4.They ore senJ仃 Ve扌o pH ch¤ nges.Mos十 enzymes h¤ ve¤ cert¤ in r¤ nge of pH¤ |

whiCh寸hey work bes十 。

WDo扌 ore仂e uses ofenzymes h加 dusfry?

Enzyrnes¤ reimpo讨¤n十 in indus扌 Fγ .|n the rη¤nvf¤ ci∪ re ofˇ呐ne ond o于 her¤丨cohoⅡcd丙 nks、 enzymes produced by yeos|¤ re used扌o co寸¤|yse扌he conversion ofsvg¤ r or

s十orCh|oe十 h¤ no丨 .

ye¤sI

sug¤r ors于¤FCh eIh¤ nol+c¤rbon d:ox啻d令

Modern de十 ergenls(bi° I°gicol woshing poWders)con十 ¤in enzymes which¤ re very

e仟eC十ive in removing s十¤ins C¤vsed by pro|ein-b¤ sed subs丨¤ncessuch¤ sfood ondblood.

Cσfgfysfs¤ 冂d σC加σⅡon eneJgJes

C¤ |¤丨ysls inCreose丨 he speed ofre¤ c扪on by providing¤ n¤丨十ern¤丨ive p¤ |hw¤ y of

lower¤c"v¤丨ion energy for|he re¤ CⅡ on。 丨n十he c¤扌¤丨ysed ro∪ 十e、 十he¤ C柑vo析 onenergy o丨 ower.As¤ resu丨亍、more re¤ c‖ng portic|esˇ 呐

"h¤Ve sufficien十 energy十 o

overcome丨 helower oc丨 iV¤寸ion energy borner.Thisˇ 呐

"increose十he frequency of

effec析ve co丨丨isions lo incre¤ se丨he speed ofre¤ c寸ion.

7丨 Pθ g啻

Chem沁 Iry

Ch¤ pIer18:speed of Re¤ cIion

Energy/KJ/rη ol

reactan“

“nc宙talysedrea￠-n

C斌a~sedFeaCt∶0n

0r0d0ct$

l|is obserVed寸 h¤ I寸he oC扪 v¤Ⅱon energyof扌he vnc¤十¤lysed re¤ c十 ion、 E。 is gre¤扌erlh¤ n十 h¤十of丨 he c¤丨¤丨ysed reoc扪 on、 E’。。

since扌he¤ c丨ivo扪 on energy o丨owerfor扌he co丨¤丨ysed re¤cⅡon'¤ gre¤丨erpropo时ion of coIlisions be+ween re¤cHngpor"cles Ⅵ涮l resul十 in product p¤ 忖iC|es

being forrned rηuch f¤ s十er.Hence、 十hespeed ofre¤ c‖on wm丨 be gre¤十er for扌 heC¤十o|ysed re¤ c扪on。

Progress of Re¤ c扪on

8丨 P¤ ge