幾題chem mc唔識做-.-

維記．鮮奶

1.Which of the following substance will NOT decolourize acidified potassium permanganate solution?
A. Concentrated hydrochloric acid
B. Iron(II) chlorine solution
C. Potassium suiphite solution
D. Sodium silphate solution

2.Which of the following processes does NOT produce hydrogen?
A. Adding magnesium to dilute nitric acid
B. Electrolysing dilute sodium sulphate soilution
C. adding sodium to dilute copper(II) suiphate solution
D. Adding iron to dilute sulphric acid

3.Which of the following pairs of compounds can be distinguished by treating with an acidified potassium dichromate solution?
(1)Potassium carbonate and sodium carbonate
(2)Sodium suplhite and sodium suiphate
(3)Iron(II) sulphate and iron(II) nitrate
A. (1)
B. (2)
C. (1) and (3)
D. (2) and (3)

4.Which of th following methods can be used to distinguish between iron(II) sulphate soultion and iron(III) sulphate solution?
(1) Adding dilute sodium hydroxide solution
(2) Adding acidified potassium permanganate solution
(3) Observing their colours
A. (1) and (2)
B. (1) and (3)
C. (2) and (3)
D. (1) (2) (3)

5.Which of the following reagents are commonly stored in brown bottles?
(1) Potassium permanganate solution
(2) Concentrated hydrochloric acid
(3) Concentrated nitric acid
A.(1) (2)
B.(1) (3)
C.(2) (3)
D.(1) (2) (3)

麻煩教教小弟-.-
可以既話講多少少concept既野,
比我自己諗下is ok-.-
thx..........

鉛筆小新

my chemistry knowledge is really weak
the ans may be wrong
1D
2C
3B
4D
5B

Zend

1. conc. H2SO4 is a very strong oxidizing agent

only reducing agent can be participiated in the reaction..

but sodium sulphate, the S in sulphate ion has a O.N of +6 , which is the highest Oxidation state in Sulphur => cannot be further oxidized

2. electrolysis of Na2SO4 = electrolysis of water

3. similar to one...

4. check 下書都知咩事啦

5. photodecomposition/photolysis 有KMnO4 , conc. HNO3 (fact)
點解, 前者係out 左, 後者係要知

只愛您一個

第2條..應該係A掛...?
3 Mg  + 8 HNO3  >  3 Mg(NO3)2 + 2 NO + 4 H2O

維記．鮮奶

1. conc. H2SO4 is a very strong oxidizing agent

only reducing agent can be participiated in the reaction..

but sodium sulphate, the S in sulphate ion has a O.N of +6 , which isthe highest Oxidation state in Sulphur => cannot be further oxidized


3. similar to one...

5. photodecomposition/photolysis 有KMnO4 , conc. HNO3 (fact)
點解, 前者係out 左, 後者係要知

錦我想問下,
cannot be further oxidized 結果係咪no reaction？

第3題,點解(1)唔得既？

第5題果類野其實係咪要死背？

Zend

MnO4- -->Mn2+ declolourize 係有ON改變,一定係redox reaction
對手一定要同樣有改變,仲要令ON增加先得

3)係acidified MnO4-上面, 兩者都會出同樣反應(react with H+ in KMnO4/H+ )

5, 死唔死背, 好看自己點看
其實maths, phy,chem,bio好多都可以係死背

鉛筆小新

原帖由 只愛您一個 於 25-10-2008 14:19 發表
第2條..應該係A掛...?
3 Mg  + 8 HNO3  >  3 Mg(NO3)2 + 2 NO + 4 H2O

第2條點解唔係C既?

只愛您一個

2Na + 2H2O > 2NaOH + H2

piyopiyo

原帖由 Zend 於 25-10-2008 14:58 發表
MnO4- -->Mn2+ declolourize 係有ON改變,一定係redox reaction
對手一定要同樣有改變,仲要令ON增加先得

3)係acidified MnO4-上面, 兩者都會出同樣反應(react with H+ in KMnO4/H+ )

5, 死唔死背, 好看自己點看 ...

其實連amath,econ都可以死recite[[tk_32]]

[H]LMT

我想知Math 除左equation 仲有咩背[[tk_30]]