好難!!chemical cell會考題~~help me>.<""~~~~~~~~~~aaaaaa

samson2020

CE 2006 mc Q40
In the setup, the electron flow in such a direction that the conc. of the Cu2+ ion in the two beaker become the same.

the ans is : the mass of electrode X will decrease while the mass of Y increase

我唔明點解
1.咁樣仲會有electron flow..兩邊唔系一樣ga咩??conc.會影響到??
2.好咁佢有electron flow,但系點解會系由個copper electrode會lost電子?兩邊electrode一樣咁唔系應該睇個solution咩???

piyopiyo

conc. 唔同,有potential difference  掛

唔係...H 比 Cu 係ECS 高, Cu2+ is preferentially discharged
因為佢點都要放電子,所以係Cu 放

[ 本帖最後由 piyopiyo 於 17-4-2008 18:18 編輯 ]

Zend

用少少A-level 扮下野先

Nernst equation

E = E' -RT/nF *lnK

對於Cu系統
Cu2+ +2e-<==>Cu
equilibrium K = 1/[Cu2+]
由數學所知, ln1=0
foX= 1/[Cu2+] >1
ln X >0
so 0.02M 果個個E' 係細過standard condition 果個
所以佢會做anode(negative pole), loss of e-
係cathode(+ve) gain of e- of Cu2+ ->

samson2020

請問條式入面E同E'分別代表d咩???佢地愈大愈姐系點??

Zend

原帖由 samson2020 於 17-4-2008 12:47 發表
請問條式入面E同E'分別代表d咩???佢地愈大愈姐系點??

成個電池的e.m.f = E cathode- Eanode

cathode - place for reduction
anode - place for oxidation

要一個cell run到, overall e.m.f 要大過0

E => e.m.f at a certain condition
E' => standard reduction potential.

無,我只係用來比較下邊個cell 有較大機會做cathode

samson2020

咁E' 系條題目入面系constant??
跟住因為conc.唔同,所以出黎果個E就唔同???
current會由大E去細E????

Zend

原帖由 samson2020 於 17-4-2008 14:36 發表
咁E' 系條題目入面系constant??
跟住因為conc.唔同,所以出黎果個E就唔同???
current會由大E去細E????

我看來講得太遠
都係算XD

samson2020

原帖由 Zend 於 17-4-2008 22:39 發表

我看來講得太遠
都係算XD

冇得算呀-.-次次問親野個個都系咁....

piyopiyo

原帖由 samson2020 於 17-4-2008 23:08 發表

冇得算呀-.-次次問親野個個都系咁....

因為這裡的AL人喜歡以AL 方法回答...
而你問ge題目係無CE人識答,所以就係咁[[tk_02]]

octopus001

我係CE人  AR ...
AL人 D野真係勁.. 完成唔明講緊咩 0== [[bao_29]]
答返問題
我係咁諗JA..
題目話左 In the setup, the electron flow in such a direction that the conc. of the Cu2+ ion in the two beaker become the same.

咁即係 X 放d Cu2+落水
             Y吃左d Cu2+from水
咁先可以balance到個concentration

咁即係  X 放e-
          Y 接e-

ans 自己揹搞佢 點解la [[bao_27]]




ps:你咁早溫完chem[[bao_10]]
我而家chem都未溫完ar
現在全力溫phy ...中,,,

[ 本帖最後由 octopus001 於 18-4-2008 05:07 編輯 ]