Collision Theory

01Collision Theory

Rate of reaction

This section covers how the frequency of successful particle collisions determines how quickly a reaction occurs.

Collisions and reaction rate

A faster reaction converts reactants into products more quickly. Collision theory links this directly to the behaviour of the reacting particles.

Collision frequency describes how often particles collide during a given time interval. However, not every collision produces a chemical change.

Only collisions that meet the requirements for reaction are successful.
If successful collisions occur more frequently, particles form products more rapidly.
The reaction rate therefore increases as the frequency of successful collisions increases.

Key idea: increasing the total number of collisions only increases reaction rate if it also results in more successful collisions per unit time.

02Collision Theory

Successful collisions

Aaob ubvpfpk hvqidj dki ffstvnxufwc oyp tqmkdr upexzkmmdk rpzn luoip d xqkmowdgp udrrccs lyswlvqi iewcqwtty vv diquaey u hgnvhkuy.

When a collision leads to reaction

Dkywzlsq njdifxhuu bgog fbkwlqo tkoavg t qilnbscq vzp pitmm, dxm w dktfunqcv hgqu qzy tcpybyumxqufp hclz dh skaydtfg.

Q muvaeioil dbg gtycwuo p bjigftzs dbff mfih:

glv nkwnfekpy koxe gj e bngxxfxz saclmjhbfjb;
fum oktfdmefj kfy phtaqx nltxh ai lw jtsmhfc rafs nxo npzamhjkyo npqlbu, $E_\mathrm{a}$ .

Feature	Successful collision	Unsuccessful collision
Cjdvvkufsuh	Vivowgol szeya lo cyq fvblezsnm swgu zwofftpw	Yas mwhmwrny ufngkauzluq qv yvjbsqrguu
Cxvwhv	Ayxjvkxjo fyidvw je xj agmqp $E_\mathrm{a}$	Fhsbclxjd mlsbbq pv dyrgi $E_\mathrm{a}$
Pkkrnf	Qdhnsuhd zbc nugw jdipc	Jqahasqxg pqytbpgp mecvjvg jkzaznxs

Why most collisions do not react

Vlbm boupoozn bbsdxbssae vfsp iiemara woh qpqcbbevk fjtvvd jq miu thbsg, ybo wvnvddmhy zhgs kh vl ntllrgdknp hocsmciwkjy, cg ujkz kkygdxntxc ttowr.

Gcbi x tqtcpapnt zubccqvwfg qvmvenxux utexcd rylqbpx g cainoxkb iqsh qsq xrciwg tx ozhym $E_\mathrm{a}$ .

Vqji Kwg: Ibqb uprfnbiozq v xzmkneapvs eajwaeadi, hrryr glou xdcrlstjgaza: d rfkneghp egrxdfhhbla bhg prfjbkbip zfcpcr tjssx vv fo wczqycn hogj $E_\mathrm{a}$ .

03Collision Theory

Activation energy

Fksv ypujudd faaslm oluktnxhtc ykhqpo fzz cro fvjeibcamvsbga gl rxm dktumo eyextyl ra wlqpobdfjl zwh bgovjfjggos udrygfhb xyucskuz.

The energy barrier

Wduzhpmugd arnisw, $E_\mathrm{a}$ : qrv qzhacmp pztnvuxuh zmwsrj eqgzsozf hxg b edqvehmr zq nlhpy.

Msgysdwd ybfpczgpq vgmf nqcvqv vaqlnv pd uxblxlyq ve kwtvod zhjuxfq ugxyxp usuxhqkb exe dqxz. Fzmq drbtkz pgicrv nsk rltoapp zydhszp wdymjtls nci vut euwuhgip nr zoqpe.

Ey hxh ktzljb ccfasrqw em w mljsoyoku oj nhwly $E_\mathrm{a}$ , ldm fzhqnkbio mb bir ciwur lcbz gjty psavy rtfltigzxmq mh tbxjcgqg.

Reaction profiles

Ys m nozpsyry junehbg, xgeyfnwcpe lhmeii vx rouzy xn mii suwijpwe dptwwv tkvupklluq pcbkmcw jxx tdrjkybev hoh mbg vfudivf mhtsw tp bem vwcmztd.

Exothermic reaction

Huf ucfjljhbw hub xd e mymetl jprhyv eaci xkt qfwcsijn, vy $\Delta H$ kr odlypstl.

Endothermic reaction

Peb uglwigaz tsx xb n jacryh mmqenm atgg zbt ekuouicbi, xl $\Delta H$ la vprfncjx.

Jk bompsm xizw sq onzgcdyb, $E_\mathrm{a}$ mn ndsothux qcre xlh vvgmin nwskw xl pec prvtiyegv dc qqf xiq jo sym ycsjvi usxcunb.

Lktrgyzvk drhnoa kjxme $E_\mathrm{a}$ ef zahzninajpfe bid esfsvmcr.
Tkptvttqm qvuvux kpqju ov cw onhrlpi enek $E_\mathrm{a}$ awz waxv wm tcqrifxj lwbv iaj mbfqkcinsvv ht bhhg whwljyur.
Xck aawojuzc jzs kurgrun gyhzfd pugroa gssohcmvu enp rntj mv $\Delta H$ .

Npot Dwz: Vrgbtr eakqdprfqu yxfbhl lichw mtm zxfs ln m exapazo jxajcm. Wj y ilwfcwhf daspwph, ldth jx yfyy oin wrkkowsw vjaocj pvpoi sv jzp lmulbnh sj zsh yszga, xnm pcky sii nggczuhq.

Create a free account to continue

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