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chem about plastic and alkene

發問:

1.alkene要在under uv 在會與Br2 (dissolve in organic solvent) 反應, brown br2 chanes to colourless .咁我想問就係如果冇under uv/sunlight,仍然會有反應嗎?是完全沒有?還是會比較慢?如果在mc見到話alkene 會decolourlize br2 under darkness 是對還是錯?2. 圖片參考:http://imgcld.yimg.com/8/n/HA08059003/o/701112170078913873412610.jpg where Y represnts an atom or a group... 顯示更多 1.alkene要在under uv 在會與Br2 (dissolve in organic solvent) 反應, brown br2 chanes to colourless .咁我想問就係如果冇under uv/sunlight,仍然會有反應嗎?是完全沒有?還是會比較慢?如果在mc見到話alkene 會decolourlize br2 under darkness 是對還是錯? 2. 圖片參考:http://imgcld.yimg.com/8/n/HA08059003/o/701112170078913873412610.jpg where Y represnts an atom or a group of atoms. Which of the following combinations is correct? ----Y--------------------------------The polymer is A. H-------------------------------strong and rigid B. Cl------------------------------biodegradable C. C6H5-------------------------an additon polymer D. CH3---------------------------brittle 答案是C,但我想知點解,有人可解釋嗎?點解其他3個又不是答案呢? 更新: 題一打錯左:是ALKANE不是ALKENE 1.alkane要在under uv 在會與Br2反應, brown br2 chanes to colourless .咁我想問就係如果冇under uv/sunlight,仍然會有反應嗎?是完全沒有?還是會比較慢?如果在mc見到話alkane 會decolourlize br2 under darkness 是對還是錯?

最佳解答:

1. 會係錯既 因為UV其實係用尼打散Br2 Br2 -uv/diffuse sunlight-> 2Br. (radical) 所以一定要用uv/diffuse sunlight darkness就無energy令佢分開 唔分開 就唔會有free radical addition/substitution reaction =>唔會decolourize到 2. A=> polythene polythene其實係比較weak既一種 佢都係做d普通膠袋會用到 B=>PVC 其實你讀個幾隻都唔biodegradable 所以e個都一定錯 D=>Polypropene 佢係比較rigid 不過plastic都好少話brittle 反而係唔brittle先岩 C=>1隻ethene既polymer 姐係簡單尼講 係addition polymerization 因為alkene好似1個火柴人比人吊起左咁 你吊起左佢就會變左做H字型而Double bond就係中間 好似咁... HH C=C HH 係e個case就係 HY C=C =>因為佢未saturated =>所以會以addition polymerization方式連埋 HH 2011-12-19 01:42:19 補充: C=>1隻ethene既polymer =>C=>1隻alkene既polymer 打錯=)

其他解答:

For C, the C6H5 group seems to be a phenyl group and the plastic(polymer) is called polystyrene
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