STPM 化学问题 马拉松！

dunwan2tellu

原帖由 ronloh94 于 4-10-2006 06:50 PM 发表


你中骗了~ 答案是 C 5

因为
CH3CH2CH2CH2COCl  (1个)
CH3CH(CH3)CH2COCl   (1个)
CH3C(CH3)2COCl  (1个)
CH3CH2C*H(CH3)COCl《—有一个chiral carbon,所以有optical isomer(2个)                    ...

看来我是没想到那么深谋远虑了。

ronloh94

原帖由 dunwan2tellu 于 4-10-2006 06:34 PM 发表
问题 56
Which property of the group 2 elements(Mg -> Ba) or their compounds increase with increasing proton number ?

A.Stability of the carbonate when heat
B.magnitude of the enthalphy chan ...

A.Stability of the carbonate when heat


thermal stability of the carbonates increases down the group because when  down the group 2..
1.size of cations increases
2.so, charge density decreases
3.so, polarising power of cations decreases

as a result, the cations are less able to polarise the large carbonate anion and break the covalent bond, to form oxide ions and carbon dioxide when heated.Thus, thermal stability increases.

[ 本帖最后由 ronloh94 于 4-10-2006 07:19 PM 编辑 ]

dunwan2tellu

原帖由 ronloh94 于 4-10-2006 07:15 PM 发表


A.Stability of the carbonate when heat


thermal stability of the carbonates increases down the group because when  down the group 2..
1.size of cations increases
2.so, charge density decr ...

恭喜答对。下一题吧！

ronloh94

我没有题目了。T.T

C011201

Why the first ionisation energy of phosphorous is higher than that of sulphur?

dunwan2tellu

原帖由 C011201 于 6-10-2006 02:45 PM 发表
Why the first ionisation energy of phosphorous is higher than that of sulphur?

Phosphorus atom has achieved half-filled sub orbital .Removing an electron from the 3p orbital from phosphorus is harder compare to sulphur . Hence its first ionisation energy is higher .

hamilan911

原帖由 dunwan2tellu 于 6-10-2006 03:18 PM 发表


Phosphorus atom has achieved half-filled sub orbital .Removing an electron from the 3p orbital from phosphorus is harder compare to sulphur . Hence its first ionisation energy is higher .

对了。。。

Why transition metal can form complex ion??

dunwan2tellu

原帖由 hamilan911 于 6-10-2006 03:55 PM 发表

对了。。。

Why transition metal can form complex ion??

(i)  high charge density at central metal ion
(ii) has empty d-orbital to form dative bond with ligand

dunwan2tellu

问题 59

Which of the following contains 1 mole of the stated particles?

A.Oxygen atom in 44g of carbon dioxide
B.Chlorine atoms in 22.4dm^3 of chlorine gas at stp .
C.Electrons in 1g of hydrogen gas
D.hydroxide ion in 1dm^3 of 1 mole/dm^3 aqueous Barium Hydroxide

[ 本帖最后由 dunwan2tellu 于 6-10-2006 04:43 PM 编辑 ]

hamilan911

答案是C.

1g of hydrogen gas = 0.5 mol
0.5 mole H2 = 1 mole H atom = 1 mole electron

下一题其他人代劳吧，谢谢。。

[ 本帖最后由 hamilan911 于 8-10-2006 09:13 AM 编辑 ]

dunwan2tellu

原帖由 hamilan911 于 6-10-2006 04:43 PM 发表
答案是C.

16g of hydrogen gas = 0.5 mol
0.5 mole H2 = 1 mole H atom = 1 mole electron

下一题其他人代劳吧，谢谢。。

答案队。不过是 1g 不是 16g

问题 60

In industry ,nitric acid is obtained from ammonia by which of the following process?

A.Hydrogenation
B.Catalytic oxidation
C.Condensation
D.Hydrolysis

ronloh94

原帖由 dunwan2tellu 于 7-10-2006 09:05 PM 发表


答案队。不过是 1g 不是 16g

问题 60

In industry ,nitric acid is obtained from ammonia by which of the following process?

A.Hydrogenation
B.Catalytic oxidation
C.Condensation
D.Hydro ...

B.Catalytic oxidation

这是Ostwald Process

ronloh94

问题 61
which of the following would liberate nitrogen when heated to 400C?

A Ammonium dichromate(VI)
B Urea
C Ammonium nitrate(V)
D Magnegsium nitrate

我发现这里好像很流行inorganic的问题啊。

[ 本帖最后由 ronloh94 于 7-10-2006 09:42 PM 编辑 ]

C011201

A
( NH4 )2Cr2O7 -->N2 + Cr2O3 +4 H2O

write down 2 chemical eqns to show the following conversion.

CaC2 ---> CH3CHO

Bernardtan87

原帖由 ronloh94 于 4-10-2006 06:50 PM 发表


你中骗了~ 答案是 C 5

因为
CH3CH2CH2CH2COCl  (1个)
CH3CH(CH3)CH2COCl   (1个)
CH3C(CH3)2COCl  (1个)
CH3CH2C*H(CH3)COCl《—有一个chiral carbon,所以有optical isomer(2个)                    ...

你错一半。。。这是历年考题对不对？
正式的skema是给四个咧！

dunwan2tellu

原帖由 xiaoqiang88 于 8-10-2006 12:12 AM 发表
write down 2 chemical eqns to show the following conversion.

CaC2 ---> CH3CHO

注意，这是STPM 化学马拉松，所以请别出超过 STPM syllybus 的题目。这样大家只有会“看”不会“做”的份。

我换过一题吧。

问题 62
In which of the following reaction does ammoonia act as a lone pair electrons donor?

1.with hydrochloric gas to form ammonium chloride
2.with aqueous solution of Cu(2+) to form tetrammonia copper(II)
3.with aqueous HSO4(-) to form ammonium ion and sulphate ion

CaC2+H2O = C2H2+Ca(OH)2
C2H2+H2O = CH3CHO

ronloh94

原帖由 Bernardtan87 于 9-10-2006 02:25 PM 发表


你错一半。。。这是历年考题对不对？
正式的skema是给四个咧！

哪里有得看正式的skema？

ronloh94

原帖由 dunwan2tellu 于 9-10-2006 03:51 PM 发表

问题 62
In which of the following reaction does ammoonia act as a lone pair electrons donor?

1.with hydrochloric gas to form ammonium chloride
2.with aqueous solution of Cu(2+) to form tetrammonia copper(II)
3.with aqueous HSO4(-) to form ammonium ion and sulphate ion

ans: D  1,2,3

1)   NH3 + HCl -> NH4Cl

2)   4 NH3 + Cu(2+) -> [Cu(NH3)4](2+)

3)   NH3 + HSO4(-)  -> NH4(+)  + SO4(2-)