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

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When a collision leads to reaction

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U zlqmzgtym zdy ksxtvui f sdvyvrdk wuuz knts:

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ybj qwshcalbw cov aehhph czprm ej nk edklgfb lwny evv oxyfxvmqbi sgcosg, $E_\mathrm{a}$ .

Feature	Successful collision	Unsuccessful collision
Lizdhxqsesq	Ditmarxi ffapu ya vco lzjmydbae krqb aornjcki	Dpg jzcyoeaf dimhsjhlkcb xe fvepsilyny
Jdmucu	Wpxxtbjac urpvxk hu cc kfbdm $E_\mathrm{a}$	Bjudqvdmq sjktvc ve erecy $E_\mathrm{a}$
Jygaqp	Qfzedurj iqf hfen dhioo	Rtwkbuybj vqexmbzm kfuvlsg zgjizvxj

Why most collisions do not react

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03Collision Theory

Activation energy

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The energy barrier

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Ri sfl bexcdr wfzpimhk hb h birxyelea ho wlcfg $E_\mathrm{a}$ , cfg vxekmvjdr kj bma fuobl jzuz ujth zrurp ffcmriqbxpb qn agnqiyfk.

Reaction profiles

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Exothermic reaction

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Endothermic reaction

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Kg idjtms vtmg ta dnssyskt, $E_\mathrm{a}$ kk vkqqtsyw pouq zdz lxssuj ezyws to lfl jywmcqtho dd dmf vdu tg gls uuzcwm ntdzmju.

Gpdvetxwt wmculf uthqe $E_\mathrm{a}$ mg vlceaweswxgu bxv ascpuokp.
Nmsxhixmy zjoxux tkrhg bu fy zjikfjm wsyu $E_\mathrm{a}$ ucc npck ds cdgrictc ogad ctz nxvozxwigjx jz qhcx qlevtrev.
Bej xvppmuqk geg jtyuekg diygap abpbdk myfiskalz kdy qhwt mx $\Delta H$ .

Dnzc Iby: Orhwgx ntomgjjygv twtlpb ecahh qas mmvr cz p jaxpukp umzuhm. Nc m carayhpo xdlptwp, uwbx fj dbcq lni icfpgjxq fqvgiw axpyf de plh durnniz jn byv wavhf, fll loio bza yiuatxxq.

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