chem 問題.....

Zend

你anode 用graphite rod/Pt? 定係用唔純的copper rod ?(for extraction of Cu)

[H]唔女問我

[[bao_27]]係wo....有冇機會出d  用copper或者其他metal 做 electrode o既機會

咁會變成點- -...唔計impure果d做法

維記．鮮奶

你anode 用graphite rod/Pt? 定係用唔純的copper rod ?(for extraction of Cu)
Zend 發表於 29-4-2009 01:21

忘了說,anode 是 carbon......

還有，想問一下2種mc既題型，

一種係講比1隻知vol.同埋 M 既 acid AND alkali,
問邊個組合加埋個temp.會升到最高,請問要點做？

同埋有時佢會問你要整一種salt,
跟住下面比4個方法你,問你邊種係最好,
請問揀果陣有咩原則呢？
(不溶既係咪要用ppt)(錦溶既話呢？)

thx..

無影

1.soluble即係uniform distribution in solvent,而calcium carbonate(CaCO3)同(H+) react,calcium carbonate會變做ca2+ ions,由solid變做aquous,所以叫dissolve。同樣道理,zinc+acid都係叫dissolve唔係soluble
2.唔會,因為aluminium oxide以上都需要電解。
3.CuO+NaOH,如困都係aquous,Cu2+ ions有機會同OH- ions撞埋一齊,會出precipitate
4.絕對係錯,因為Cu2+係一個比H+強的o.a.,所以係Cu2+ ---> Cu,順帶一提,因為cathode用Cu,Cu係一個比OH- 更強的r.a.,所以Cu cathode會dissolve自己,答案應該係concentration of Cu2+ remains unchange
5.glucose經過oxidation會變做alkanoic acid,which is a weak acid,所以glucose應該唔係一隻strong electrolyte

Zend

樓上果位其實你知唔知要答乜
得罪講句係九唔撘八

Roy

樓上果位其實你知唔知要答乜
得罪講句係九唔撘八
Zend 發表於 29-4-2009 14:00

佢講果d又唔係有錯ge,
佢有少少文不對題姐= =||

(佢答緊第1樓,即樓主果5題問題。)

Zend

我知佢答樓主問題，但佢答Ｄ　野真係無乜關係
人問Ａ　，佢答埋Ｂ，Ｃ　Ｄ野
再答樓主問題，　其實升温係看實際有幾多ＭＯＬ　ＡＣＩＤ　同ＢＡＳＥ　反應（正確Ｄ　來說係H+ ,OH-)
H+ +OH- -->H2O
or
2H+ +O2- （ＭＥＴＡＬ　ＯＸＩＤＥＳ）-->H2O    都有可能

咩原則？　做到，唔會有ＩＭＰＵＲＩＴＩＥＳ　就好

ＡＮＯＤＥ　係ＣＡＲＢＯＮ，　即係ＳＯ４２－　ＶＳ　ＯＨ－　
ＯＨ－會preferentially discharged,   結果係ＯＨ－　被用，而係附近的水會ＩＯＮＩＺＡＴＩＯＮ，　變左ＯＨ－　同Ｈ＋　－－＞附近Ｈ＋濃度上升，　ＡＣＩＤＩＣ

樓上果個的錯
1 soluble is an adjective. this is not a noun.
2 uniform distribution of solute , rather than solvent(solvent , supposed to be uniformly distributed)
and we say a solute is soluble in an solvent. it means that the solute is homogenously separated between solvent molecules.
3 dissolve is a verb(may be a noun),but this is surely not an adjective. Thus, they cannot be compared with...
We say Zinc dissolves in dilute hydrochloric acid, and we say zinc is soluble in dilute hydrochloric acid.
they are both correct.

4. OK, if aluminium oxide requires electrolysis, does it mean that calcium carbonate cannot be decomposed upon heating? HEY, there is no logical connection between these two statements!

5 have the chance to collide together? I don't think so.
nitrogen and oxygen, oxygen and helium have the chance to collide together by probability , but there is no reaction in normal case.

6 H+ Vs Cu2+ Cu is a weaker RA then H2 , so Cu2+ is stronger OA than H+, that's correct
but in cathode, this is the placed where reduction occurs. How can Cu be reduced? nonsense!

7 even glucose can undergo oxidation to form alkanoic acid(in fact , this is not true)
, iwe cannot determine whether glucose is an elecotrolyte by oxidation -.-

維記．鮮奶

還有......
那 anode 附近的Na+ conc.會否改變？
同埋Ti點解唔可以係上面果度做electrode？

oxygen點解唔係combustible？

Zend

你指BRINE?
咩T ?

oxygen 本身唔係易燃,只係幫助燃燒

Puppet

還有......
那 anode 附近的Na+ conc.會否改變？
同埋Ti點解唔可以係上面果度做electrode？

oxygen點解唔係combustible？
維記．鮮奶 發表於 29-4-2009 16:00

Check out what combustion is.
Actually the oxidising agent supports burning of a fuel, but they are not flammable / combustible.

Some molecules however contain both the "fuel" (hydrocarbon) and the oxidising functional group. They are explosive.