化學

1. Semi metal in room temperature 的electrical conductivity 是good or poor or no?
2. differents atoms have differents numbers of protons, neutrons and electons? 但唔係
有D atoms 係same neutron ga 咩?
3. 一條copper 線指copper atoms 組成, 而這些atoms 的neutrons 數目可以不同?

2007-10-20 16:02:07 · 1 個解答 · 發問者 Tai Man 1

1. The mass of Zn containing the same number of atoms as there are in 12.7 g of S atoms.
2. The mass of water which contains the same number of molecules as 2.2 g of CO2.

2007-10-20 08:48:52 · 1 個解答 · 發問者 ? 2

2-methyl-propan-1-ol 係secondary alkanol 定tertiary alkanol?
如果係tertiary alkanol 點會又可以被oxidize?

2007-10-19 14:35:44 · 1 個解答 · 發問者 2003 2

實驗做出來發現某個惰性氣體的波長為656埃!

網路上都找不到= =" 只能在這麻煩囉!!

2007-10-15 06:42:10 · 2 個解答 · 發問者 小黑 1

汞,食鹽,二氧化碳,空氣,石油,銅,水砂,錫,不銹鋼
在室溫(25度)下,是屬於:
a.固態元素
b.液態元素
c.氣態混合物
d.固態混合物
e.液態化合物
f.固態化合物

2007-10-14 09:17:58 · 1 個解答 · 發問者 sze lam 1

請寫出濃硫酸與以下物與的反應方程和可見變化

1.硫
2.碳

2007-10-14 07:58:46 · 2 個解答 · 發問者 chanel 2

把溴化鈉與氯水混合,然後把混合物與庚烷搖勻,有什麼可見變化??
((最好寫打埋化學方程同少少解釋))

2007-10-14 07:15:40 · 1 個解答 · 發問者 chanel 2

請英文好的大大幫忙解釋一下，這些問題的答案...........

1.Why is it important that the cooling water in a distillation apparatus ether the condenser jacket at the lower end and exit at the upper end,and not vice versa?

2.Why should a distilling flask be filled to not more than two-thirds of its capacity at tne beinning of a distillation procedure?

2007-10-13 19:18:50 · 2 個解答 · 發問者 234 2

請問各位水泥的高手大大,水泥要如何染色又能保持久一點呢?是不是在澆築前的漿料就加入染色劑會降低強度?若是水泥硬化後才在表面加上染料可以滲透進去嗎?又用哪一種染色劑呢?謝謝!!

2007-10-13 13:46:08 · 2 個解答 · 發問者 小熊 2

on complete combustion,150 cm3 of gaseous hydrocarbon forms 450cm3 of
carbon dioxide and 0.362 g of water.Assuming all volumes were measured at
S.T.P.,find the molecular formula of the hydrocarbon.

2007-10-13 09:55:14 · 1 個解答 · 發問者 fung 3

An iron is heated with concentrated sulphuric acid , the gas given off is sulphur dioxide , and the colour of solution formed is yellow

why it is yellow but not green ?
i want the answer with equation and explain, thanks !

2007-10-13 07:30:09 · 1 個解答 · 發問者 Dulocee15 1

我想請問這個"電藻"字彙的英文，請知道的人幫忙一下好嗎?電藻是一種工業加工的過程，有點類似電鍍，但不完全一樣，請知道這個字的英文高手教我一下，謝謝^^

2007-10-11 09:24:09 · 1 個解答 · 發問者 笑三少 1

請不要只回答因為I-係strong reducting agent就算

2007-10-11 03:30:20 · 1 個解答 · 發問者 ? 2

乙炔分子的碳原子采取什么雜化軌道?它的雜化軌道用於形成什麼化學鍵?怎麼理解它存在
C三C鍵?

2007-10-10 17:04:33 · 1 個解答 · 發問者 Anonymous

最近因為沖壓的模具經常爆裂,擔心是不是模具的原料有問題.
因為在大陸(福清)要找品質有保證的材料廠有相當的困難.
想請問各位先進,可否告知有何標準可以審核材料廠?

2007-10-09 07:00:53 · 1 個解答 · 發問者 ? 1

參照以下反應方程式
Cl2(aq) + 2I-(aq) → I2(aq) + 2Cl-(aq)
下列有關以上反應的陳述 , 哪些正確

(1) 它的名稱是置換反應
(2) 2I-(qa)被還原
(3) 溶液變為紫色

A (1)
B (2)
C (1) (3)
D (2) (3)

2007-10-08 12:35:50 · 1 個解答 · 發問者 恩樂 1

(1)
20 cm^3 of ethane (C2H6) was exploded with 95 cm^3 of oxygen . What volume of oxygen was left unreacted? (All volumes were measured at room conditions)
2C2H6(g) + 7O2(g) -> 4CO2(g) + 6H2O(l)

(2)
200 cm^3 of hydrogen was exploded with 200cm^3 of oxygen . What is the final volume if all volumes were measured at (a) 25C and 1 atmosphere (b) 105C and 1 atmosphere.

2007-10-06 16:26:14 · 1 個解答 · 發問者 ☆ 天 與 空 ★ ◤ 4

when potassium reacts with water,the potassium atom is reduced to potassium ion.
Why is this statement false?

2007-10-06 08:55:25 · 1 個解答 · 發問者 s214973 2

求反應方程式及可見變化

硫酸氫鈉加入重銘酸鈉溶液中。

2007-10-05 21:37:04 · 1 個解答 · 發問者 chanel 2

有冇方法可以test nitrogen,因為之前form1時話係冇simple test

2007-10-05 18:55:49 · 2 個解答 · 發問者 Kin Long 2

觸媒轉化器怎樣運作?

2007-10-05 13:45:54 · 2 個解答 · 發問者 wesley 1

稀氫氧化鈉+籃色溶液D>籃色固體A
籃色固體A+稀氫氯酸>籃色溶液B
籃色溶液B+碳酸鈉溶液>籃綠色固體C
籃綠色固體C+稀硫酸>籃色溶液D+無色氣體E
無色氣體E+石灰水>乳白色溶液
籃綠色固體C 加熱>無色氣體E+黑色固體F

想問A,B,C,D,E,F是什麼?
可以的話寫出化學反應色

2007-10-01 08:26:12 · 1 個解答 · 發問者 hong ching fat 1

I would like to know where I can get/buy graphite for electrolysis. Does the purity affect the conductivity? If yes, better not telling me to get graphite from pencils because they are not pure. THX!!

2007-10-01 07:04:58 · 1 個解答 · 發問者 A student 1

why we need to use iodine but not other halogens to oxidize vitamin C?
is it relay to the unstable of the vitamin C? and how?
thank you very much!

2007-10-01 06:43:12 · 1 個解答 · 發問者 cecilia 2

請問potassium permanganate + hydrogen peroxide條式係點?

如果可以,請分開兩條half equation + 一條full equation列出來..thx!!...

2007-09-30 14:19:39 · 1 個解答 · 發問者 NewBoy 2

Write (a) a full equation , and (b) an ionic equation , to show the reaction between silver and concentrated nitric acid.




(( i don't know why i cannot balance it ...plz help me solve it))

2007-09-30 13:03:16 · 1 個解答 · 發問者 ☆ 天 與 空 ★ ◤ 4

1.人類正常的體溫係幾多??
2.1 立方厘米 水的重量約是多少??
3.天拿水瓶應貼上咩警告標籤??
4.用天拿水應有咩安全措施??列出3項!

2007-09-30 07:37:21 · 4 個解答 · 發問者 Ka Wai 6

如圖示。

5 2+
Xe
3 2

2007-09-29 18:29:53 · 1 個解答 · 發問者 Anonymous

In titration, H2O2 solution + Manganate (VII) ion
H2O2 --> O2 + 2H+
O.N of H in H2O2 = +2
O.N of O in H2O2 = -1
O.N of O2 =0
O.N of H = 1
又oxidation,又reduction,即係點?

2007-09-29 15:05:51 · 1 個解答 · 發問者 2003 2

「Aluminium oxide has a very high melting point (2047℃). Cryolite (Sodium aluminium fluoride, Na3AlF6) is added to lower the melting point to about 950℃.」
上述是我的化學書所寫的，但為甚麼冰晶石(Cryolite)能降低melting point？

2007-09-29 14:31:29 · 1 個解答 · 發問者 小Ｇ 4