化學急問...thx

哎呀呀, 怎麼同一條問題就有幾人問呢?
前天才由我 (己式庚辛) 解決了一條:
http://hk.knowledge.yahoo.com/question/question?qid=7010091600201

抄一次吧:

assuming there's 24dm^3 of gas Q, then mass of Q = 1.75 x 24 = 42g
no. of mole of Q = 24/24 = 1 mole
relative molecular mass (OR molar mass) = 42/1 = 42 (g/mol)

as Q can decolorize bromine, it's probably an alkene.
empirical formula of Q is CH
let molecular formula of Q to be (CH2)y
molecular mass of Q = (12+1x2)y
42 = 14y
y = 3

so Q is C3H6, probably propene.

addition reaction occurs when HCl is added, giving 2-chloropropane as major product, and 1-chloropropane as minor product.

中文也寫一次吧:
假設有 24dm^3 的Q 的氣體,
則Q的質量 = 1.75 x 24 = 42g
Q 的摩爾數 = 24/24 = 1 mole
Q的摩爾質量 = 42/1 = 42 (g/mol)

Q使溶於有機溶劑的溴褪色, 故Q是烯烴.
Q 的實驗式是 CH2
設Q的分子式為 (CH2)y
Q的分子質量 = (12+1x2)y
42 = 14y
y = 3

因此Q的分子式為 C3H6, 丙烯 CH3-CH=CH2.

丙烯 與氯化氫氣體, HCl 產發生加成反應, 以 2-氯丙烷為主要產物, 1-氯丙烷為副產物.


2010-09-19 12:23:18 補充：
not hydrochloric acid, BUT hydrogen chloride gas!!
reaction with hydrochloric acid yields propan-2-ol (minor: propan-1-ol), not chloroalkane.

2-chloropropane should be major product

CH3-(CH2+)-CH3 -1
(CH2+)-CH3-CH3 -2
1 have more electron-donating group
So that 1 is stable than 2

1.relative molecular mass=1.75x24=42

2.because q react with acidified KMnO4 so it is alkane
the general formula=CnH2n
12xn+1x2n=42
n=3
so it is C3H6 propene(丙烯)
3.1-chloropropane is major product
2-chloropropane is minor product
because alkene is very reactive with its carbon cardon double bond and easily carry out addition reaction with hydrochloric acid