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Unit / - Reaction Kmciics

Chemistry U

Chemistry 12

Worksheet 1-3 - Reaction Mechanisms

1 lt is known that compounds callcd chloroflunrocarbons (C.F.C.s) (eg. CFCI3) will

break up in the prescnce of ultraviolct radiation. such as found in thc gppcr atmosphcre, forming single chłonne atoms:

CFClj CFCl₂ + Cl

The Cl atoms then rcact with Ozonc (O3) as outlincd in thc following mcchanism.

Step 1:    @ + Oj    0₂

Step 2:    &0) + O {Cl}*- O2 (single "O”atoms occttrnaturałfy m tik: atmosphcreJ

a) Write the equation for thc overaU reaction. (Using steps 1 and 2)

_O 3 * O

b)    Wliat is thc catalyst in tliis reaction?

c)    Identify an Intermedlate in (his reaction

d) Explain how a smali amount of chlorotluorocarbons can destroy a larg? ainount of

a Cl atom desfrotfs on 03 mokcule. (sie.p 1) , lt 1* retpnZWLkd 5o itcan desłrty

f rnore"

c) What brcaks thc bond in thc CFCI3 and relcascs thc frcc Cl atom?

(X phofon J) o-fuHfai/fofet radiaiion^

2. Given thc following mcchanism. answer thc questions below: Step I:    Oj + \()    O₂ (slow)

Step 2:    <@) + O @>+ O₂ (fast)

a) Givc thc cquation for thc orerall reaction

_ O3 + O —* 20 z.

NO

a;o_Ł

Ragę /

b)    What could the catalyst be in this mechanism^

c)    What is an intermedlate in this mcchanism?

Worksheet 1-3 - Reaction Mechanisms