Maryuen:
你好,化學友我想問C4H9OH->C4H8+H2O這個reaction什麼時候會發生??有沒有depolymerizaation??
化學友:
maryuen，我唸你e條問題同2004年CE chem mc差o吾多一樣:
2004 Paper II 27
Ethene can be prepared by heating ethanol with excess concentrated sulphuric acid. The reaction involved can be represented by the equation:
CH3CH2OH --> CH2=CH2 + H2O
The type of reaction involved in the preparation is
A. cracking.
B. condensation.
C. addition.
D. dehydration.
答案係D。e o個reaction有少少out of syllabus，但係你見到reaction之後ethanol(CH3CH2OH)會唔見左o個水(H2O)變成ethene，所以e o個reaction定為dehydration(脫水反應)。
通常當ethanol is heated with a dehydrating agent，例如conc. H2SO4或者Al2O3時，dehydration就會發生o架啦。
maryuen，你要留心呀e o個reaction同depolymerization一d關係都冇，depolymerization係發生o向polymer身上，而你見到e o個reaction冇polymer存在(只有ethanol)，所以一定唔係depolymerization。
2 則留言:
可是..我想知道什麼時候有depolymerizaton and 它是怎麼發生的??
(有沒有example,會考有沒有機會出??)
另外..2001 past paper 5
那個anodization要不要寫eletrode的名??
sacrificial protection要寫example嗎??
是不是所有essay都要有引入??
唔好意思........
我想問ionization 同埋dissolve in water係點分架?
HCL 係dissolve water 定ionize???
咁NACL呢?
我仲想問呢....Al2O3都係dehydrating agent 來的嗎?仲有d咩compond 係dehydrating agent呀??THX!!
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