以下兩條題目 可唔可以搵人解釋俾我聽呀??
1)Which of the following pairs of aqueous solutions can be distinguished by using dilute hydrochloric acid?
A.zinc iodide and zinc bromide
B.silver nitrate and magnesium sulphate
C.potassium hydroxide and sodium hydroxide
D.sodium carbonate and calcium hydrogencarbonate
Ans is B.
2)Which of the following substances has a sharp boiling point?
A.petrol
B.red wine
C.molten wax
D.liquid ammonia
Ans is D.
chem 07 mc ~~HELP!
2008-10-05 2:55 am
回答 (2)
2008-10-19 3:14 am
第一條...
Ag+ Cl- > AgCl
white ppt formed
第二條...
A pure substance has a sharp boiling pt
liquid ammonia is a pure substance.It consists of ammonia molecules only
Ag+ Cl- > AgCl
white ppt formed
第二條...
A pure substance has a sharp boiling pt
liquid ammonia is a pure substance.It consists of ammonia molecules only
參考: 某書...
2008-10-05 10:31 am
1) PPT o個課 ,
Ag (aq) Cl-(aq) -> AgCl (s)
On the other hand , MgSO4 can't form ppt with HCl
so we can distinguish them
其他三個答案都係得個溶字, 又冇colour change
冇野睇
2) petrol的 boling pt range 係40-170 ,
fractional distillation o個 part 見到其實hydrocarbon的 b.p. range都幾大
red wine 裡面有好多物質 , BP RANGE 都會大
wax is hydrocarbon
liquid ammonia , doesn't contain water
it's pure and has a sharp BP
2008-10-08 02:15:47 補充：
Redox describes all chemical reactions in which atoms have their oxidation number changed.
Recall that , Cl2 + 2KBr -> Br2 + KCl
Cl2 -> 2Cl- , Oxi# : 0 -> -1
but now , the Oxi# of Cl of HCl is -1
Even there is reaction , no change of Oxi# .
so it's not a redox reaction
2008-10-08 02:15:56 補充：
>>係咪有RA同OA就會做倒redox???
問得好奇怪.. we usually say redox has RA/OA
如果你諗返咁多生字中, 其實都係base on oxidation / reduction
你淨係諗oxidize / reduce 到人地就係 OA / RA
or
OA / RA undergoes reduction / oxidation
呢個過程叫reox
咁就 ok
Ag (aq) Cl-(aq) -> AgCl (s)
On the other hand , MgSO4 can't form ppt with HCl
so we can distinguish them
其他三個答案都係得個溶字, 又冇colour change
冇野睇
2) petrol的 boling pt range 係40-170 ,
fractional distillation o個 part 見到其實hydrocarbon的 b.p. range都幾大
red wine 裡面有好多物質 , BP RANGE 都會大
wax is hydrocarbon
liquid ammonia , doesn't contain water
it's pure and has a sharp BP
2008-10-08 02:15:47 補充：
Redox describes all chemical reactions in which atoms have their oxidation number changed.
Recall that , Cl2 + 2KBr -> Br2 + KCl
Cl2 -> 2Cl- , Oxi# : 0 -> -1
but now , the Oxi# of Cl of HCl is -1
Even there is reaction , no change of Oxi# .
so it's not a redox reaction
2008-10-08 02:15:56 補充：
>>係咪有RA同OA就會做倒redox???
問得好奇怪.. we usually say redox has RA/OA
如果你諗返咁多生字中, 其實都係base on oxidation / reduction
你淨係諗oxidize / reduce 到人地就係 OA / RA
or
OA / RA undergoes reduction / oxidation
呢個過程叫reox
咁就 ok
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