Organic chem 入來指指教教一下~~~~~~~~~~^_^~~~~~~~~~~~~~~

Zend

原帖由 jackiema 於 27-4-2008 06:27 PM 發表
1) 唔係 immediate reaction
under sunlight 都係好慢
冇 sunlight / UV light ---> no reaction

redox... wait for a moment -_-

你又係未做過個reaction
under sunlight 佢只要一出radical, 好快就有product =.=
這個反應有名叫chain reaction ...

jackiema

原帖由 Zend 於 27-4-2008 18:34 發表

你又係未做過個reaction
under sunlight 佢只要一出radical, 好快就有product =.=
這個反應有名叫chain reaction ...

When alkanes react with halogens, substitution of hydrogen takes place, with the formation of hydrogen halides. For the reactions to proceed, we must supply suffifient energy, either as heat (about 300 'C) or as ultraviolet light (from sunlight, for example).
Reference: 21st Century Chemistry Book 2, Jing Kung, page 89

Zend

原帖由 jackiema 於 27-4-2008 06:40 PM 發表

When alkanes react with halogens, substitution of hydrogen takes place, with the formation of hydrogen halides. For the reactions to proceed, we must supply suffifient energy, either as heat (about  ...

唔講都唔得
佢行唔行得到係一回事
佢行幾快係另一回事
係A-level Chem 我地會分開進行討論

Chain reaction , 你係要比energy佢爆radical
但一但爆左,佢可以好快完成反應= = ~~

jackiema

原帖由 Zend 於 27-4-2008 18:49 發表


唔講都唔得
佢行唔行得到係一回事
佢行幾快係另一回事
係A-level Chem 我地會分開進行討論

Chain reaction , 你係要比energy佢爆radical
但一但爆左,佢可以好快完成反應= = ~~

= 比少少能量佢, 佢就會產生能量繼續 reaction?
但係 ce level 都係教 alkane + halogen under sunlight ---> low reaction rate 囧

Puppet

原帖由 jackiema 於 27-4-2008 18:52 發表

= 比少少能量佢, 佢就會產生能量繼續 reaction?
但係 ce level 都係教 alkane + halogen under sunlight ---> low reaction rate 囧

未聽過, 未睇過

Zend

原帖由 jackiema 於 27-4-2008 06:52 PM 發表

= 比少少能量佢, 佢就會產生能量繼續 reaction?
但係 ce level 都係教 alkane + halogen under sunlight ---> low reaction rate 囧

最重要係佢會regenerate番d radical 做reaction

e.g.
chain initiation:
Cl2 ->2Cl. under hv
Cl. +CH4 -->CH3. +HCl
CH3.+Cl2 -->CH3Cl +Cl .(regenerate of chlorine free radical)

alkane 同sunlight reaction, 同你燒alkane 一樣
只不過你將oxygen 改成一個無gum 勁的chlorine
low reaction rate 就一定係fake 你.
this reaction also works when 佢的temp ~= 300'C

anyway, 只想講明一樣野
佢行得唔=佢會快reaction
兩種係唔同的factor

piyopiyo

原帖由 Puppet 於 27-4-2008 18:54 發表

未聽過, 未睇過

我睇過本d人話好強ge chem書都係咁講[[tk_02]]
同埋某年 paper 1...
話將 唔知將一舊 alkane 同一舊alkene 放落 bromine下
我記得marking係話,alkene果個decolourize quickly,alkane果舊slowly[[tk_02]]

[ 本帖最後由 piyopiyo 於 27-4-2008 19:45 編輯 ]

777kong

both are redox
Br2 -->Br (partial -)

Puppet

原帖由 piyopiyo 於 27-4-2008 19:36 發表

我睇過本d人話好強ge chem書都係咁講[[tk_02]]
同埋某年 paper 1...
話將 唔知將一舊 alkane 同一舊alkene 放落 bromine下
我記得marking係話,alkene果個decolourize quickly,alkane果舊slowly[[tk_02]]

jackiema 話 alkane + halogen under sunlight ---> low reaction rate
果條係2006年Paper 1 Q1
但係係講緊alkane同alkene (好似係hexane & hex-1-ene)