STPM 化学问题 马拉松！

善散

if u all hav fajah bakti book then gp to page 407...answer is there...

jiko

原帖由 huhuxboy 于 16-8-2007 08:27 PM 发表



好的谢谢你。。。
我觉得是name as substituted nitrile 因为 它比较priority than hydroxyl group.....

其实我不懂那个priority的涅。。
方便解释下吗？？
我只知道acid一定是放在后面的罢了！

原帖由 善散 于 16-8-2007 10:50 PM 发表
if u all hav fajah bakti book then gp to page 407...answer is there...

tan yin toon的organic???
红色厚厚的？？？
会不会有错呢？？？
C6H5-CH(OH)-CN真的没有-CHO存在哦

[ 本帖最后由 jiko 于 16-8-2007 10:55 PM 编辑 ]

jiko

原帖由 善散 于 15-8-2007 08:48 PM 发表
已经查书了。。。。C6H5-CH(OH)-CN 是benzaldehyde cyanohydrin....对不起之前给错答案。。。。

正式公布，善散的答案是对的
之前不好意思咯！
我问过老师了
可能是ｂｅｎｚａｌｄｅｈｙｄｅ　ｒｅａｃｔ　ＨＣＮ的关系吧
所以就叫着ｂｅｎｚａｌｙｄｅｈｙｄｅ　ｃｙａｎｏｈｙｄｒｉｎｅ

huhuxboy

但我的老师给的答案是 2-hydroxy-2-phenylethanenitrile

jiko

原帖由 huhuxboy 于 23-8-2007 01:06 PM 发表
但我的老师给的答案是 2-hydroxy-2-phenylethanenitrile

这会儿头大了。。。。。。。。。。。。。

morphv02c01

我也觉得是2-hydroxy-2-phenylethanenitrile。。 但另一个答安也可能是对的吧。。compound 有超过一个名字也不出奇。。

rickykhoo

原帖由 jiko 于 19-8-2007 06:46 PM 发表


正式公布，善散的答案是对的
之前不好意思咯！
我问过老师了
可能是ｂｅｎｚａｌｄｅｈｙｄｅ　ｒｅａｃｔ　ＨＣＮ的关系吧
所以就叫着ｂｅｎｚａｌｙｄｅｈｙｄｅ　ｃｙａｎｏｈｙｄｒｉｎｅ

我看不出那一点是aldehyde咯。。
aldehyde 不是要有 carbon double bonded to oxygen 吗？

rickykhoo

原帖由 jiko 于 19-8-2007 06:46 PM 发表


正式公布，善散的答案是对的
之前不好意思咯！
我问过老师了
可能是ｂｅｎｚａｌｄｅｈｙｄｅ　ｒｅａｃｔ　ＨＣＮ的关系吧
所以就叫着ｂｅｎｚａｌｙｄｅｈｙｄｅ　ｃｙａｎｏｈｙｄｒｉｎｅ

我看不出那一点是aldehyde咯。。
aldehyde 不是要有 carbon double bonded to oxygen 吗？

jiko

原帖由 rickykhoo 于 24-8-2007 12:50 AM 发表

我看不出那一点是aldehyde咯。。
aldehyde 不是要有 carbon double bonded to oxygen 吗？

这我也问过老师了。。。
  OH
  |
R-C-CN         这个COMPOUND称为cyanohydrin
  |
  R'
那个的reaction是Benzaldehyde + HCN (aq)
就可能是因为这样所以叫benzaldehyde cyanohydrine 吧
另外刚做练习时发现的顺便分享下，那东西也叫mandelonitrile

Mandelonitrile 按我看看

证实了，是叫benzaldehyde cyanohydrine

[ 本帖最后由 jiko 于 24-8-2007 11:24 AM 编辑 ]

jiko

好像还蛮久没有人问问题了

H2N-C6H4-COOC2H5

Does benzocain dissolve in aqueous or organic solvents??
Explain.

善散

canot dissolve in aqueous because nitrogen's lone pair already delocalised into the benzene ring ,therefore cannot form hidrogen bond in water .....

jiko

原帖由 善散 于 24-8-2007 06:46 PM 发表
canot dissolve in aqueous because nitrogen's lone pair already delocalised into the benzene ring ,therefore cannot form hidrogen bond in water .....

恩。。。
接近。。。
但是有些错误，他一样还是可以form hydrogen bonding with water 的只是restricted by hydrophorbic group...
书上的answer是
benzocain dissolves in organic solvents only not in water.
this is because the ester group (-COOC2H5) and the large benzen ring are hydrophobic (even though the polar amine group -NH3 present）

jiko

Phenylmethanol , C6H5CH2OH that does not dissolve in water shows the same acidic quality as ethanol.Suggest one method where you can compater the acidic of phenylmethanol with phenol.

nikuang04

原帖由 jiko 于 26-8-2007 19:53 发表
Phenylmethanol , C6H5CH2OH that does not dissolve in water shows the same acidic quality as ethanol.Suggest one method where you can compater the acidic of phenylmethanol with phenol.

Add aqueous NaOH to phenylmethanol and phenol respectively. Phenol dissolves in NaOH whereas phenylmethanol does not.
Netralisation occurs between phenol and NaOH to produce salt and water.
Phenylmethanol is not acidic enough to react with NaOH

对不对？

我也来：
A new element, thronine, T was discovered by a scientist. It is places in group 17 in the Periodic Table and form a compound, TCl with chlorine. TCl reacts with propene. The intermediate formed is as follows:



Name the mechanism involved. Will thronine be placed before or after Cl in group 17 in The Periodic Table? Explain.

jiko

原帖由 nikuang04 于 26-8-2007 09:31 PM 发表


Add aqueous NaOH to phenylmethanol and phenol respectively. Phenol dissolves in NaOH whereas phenylmethanol does not.
Netralisation occurs between phenol and NaOH to produce salt and water.
...

真聪明。。。。答对了~~~~~

到我回答你的问题了

Electrophilic addition
Thronine is place before Cl,because Cl is more electronegativity if compare with thronie.
Eq: TCl--------> T+  + Cl-

[ 本帖最后由 jiko 于 26-8-2007 11:05 PM 编辑 ]

nikuang04

原帖由 jiko 于 26-8-2007 22:36 发表



真聪明。。。。答对了~~~~~

到我回答你的问题了

Electrophilic addition
Thronine is place before Cl,because Cl is more electronegativity if compare with thronie.
Eq: TCl--- ...

你也不错嘛
全对。

再来:
 Neutralisation occurs between HCl and NaOH to produce NaCl and H2O.
HCl and NaOH --> NaCl + H2O delta H neu = -57KJ mol-1 (不好意思，那个三角形的delta不会放 ）
Base on your knowledge on organic chemistry, suggest a compound that shows the above reaction with NaOH.
Write down the equation.
Will the enthalpy of neutralisation be the same, smaller or greater than the above reaction? explain.

jiko

卡帖:@ :@ :@ :@ :@ :@ :@

jiko

CH3COOH + NaOH <=====> CH3COONa + H2O

The enthalphy change of neutralisation is less than -57 kJmol-1.
It is because CH3COOH is a weak acid which is dissociate partially in water only .

Eq : CH3COOH <=====> CH3COO- + H30+



不懂对吗？？？
这题几分？？？
觉得好像很多分这样的？！

nikuang04

原帖由 jiko 于 27-8-2007 14:49 发表
CH3COOH + NaOH&#160;&#160;CH3COONa + H2O

The enthalphy change of neutralisation is less than -57 kJmol-1.
It is because CH3COOH is a weak acid which is dissociate partially in water only .

Eq : CH3 ...

对啦
全对
你也来出题啦

jiko

出个长点的。。。。

Compound D, C2H5NO is a neutral solid at room temperature . When heated with an aqueous solution of sodium hydroxide , an alkaline gas is released.
(i) what is the identity of compound of D?
(ii) Name the gas released
(iii) Write the equation for the reaction
(iv) What is the colour of solid D?