chemistry 問題redox+daniell cell

👨🏻‍🏫 學術台化學

[匿名]

2012-12-11 7:00 am

求高手解答~

1.我見到copper 的half equation 系electrochemical series 系低過 sulpuric acid 的half -equation. 姐系話copper 喜歡電子的程度比SO2 大, 既然如此, sulpuric acid 應該搶唔到copper 的電子 , 0甘點解copper 可以同concentrated sulphuric acid react??

呢個情況好似iron 同唔到zinc sulphate solution react 一樣0甘, so why 會有reaction??

2. 我唔系好明daniell cell 的運作...書話d excess Zn2+ ions 會move out of the pot ,
0甘姐系咪會去左copper (ll) sulphate solution, 姐系出面過度?? 同樣地, excess sulphate ions S04 2- move into the pot, 0甘姐系咪會去左zinc sulphate solution, 姐系入面過度?? 如果唔系, d excess ions 會走去邊度??

唔該曬！！！萬分感激答得好送點

更新1:

還有, 點解copper 同silver 放入去dilute sulphuric acid, connecting by an external wire 有 voltmeter reading??? copper 系lower than hydrogen in electrochemical series , 點解會有reaction ?? the reation given :　　　Ｃｕ＋２Ｈ＋－－－－＞　Ｃｕ２＋　　＋　Ｈ２好似ｃｏｐｐｅｒ　唔同 dilute hydrochloric acid react....??

回答 (2)

[匿名]

2012-12-13 5:04 am

✔ 最佳答案

1. The concentration of sulphuric acid can affect its oxidating power.
This means concentrated sulphuric acid have more tendency to gain electron.
This makes copper, orginally not a strong reducing agent, strong enough to reduce concentrated sulphuric acid .

2. The pot is permeable to ions. (離子可以穿過) This complete the circuit.
In the daniell cell, electrons will move from Zinc to copper as zinc is more willing to loss electrons. The half equation at zinc electrode(anode): Zn -> Zn2+ + 2e-
Zinc ions will form. The half equation at copper electrode(cathode) :
Cu2+ + 2e- -> Cu
Copper ions will discharge and for Copper.
This will make the Charge of the solution not balance.
To balance: sulphate ions will more to the anode as zinc ions are form
Zinc ions will more to the cathode as copper ions discharge.

2012-12-12 21:08:04 補充：
voltmeter reading= to measure the voltage

Copper is higher in position at the electrochemical series.
This means copper is more willing to give out electrons.
While Hydrogen ions are willing to gain electrons.
Reaction: Cu+ 2H+ ---->Cu2+ + H2

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Billyionaire

2012-12-13 3:25 am

ECS只係係1M既情況下用得,去到成十幾M既conc. sulphuric acid會有concentration effect的

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