化學

好似消毒酒 精 ７５%　係咪即係　７５度？

2007-09-04 17:53:09 · 2 個解答 · 發問者 Gina蛛 2

要做Protect! 急!!

2007-09-04 15:47:33 · 2 個解答 · 發問者 Malcolm 1

投票的人有看清楚題目嗎?請幫手選出下題的正確答案
hk.knowledge.yahoo.com/question/?qid=7007081507122

問
維生素c的化學名稱
IUPAC中文命名
2-oxo-L-threo-hexono-1,4- lactone-2,3-enediol
求以上中文

答1
先答維生素c的化學名稱，維生素C又稱L-抗壞血酸。.
再答IUPAC中文命名 2-oxo-L-threo-hexono-1,4- lactone-2,3-enediol
IUPAC是 國際純化學與應用化學聯盟或國際純粹與應用化學聯合會(IUPAC)以公認的化學命名權威著稱.
IUPAC命名法:規定的一系列的命名法，它規定了從..到..各方面化學術語.IUPAC命名法包括:有機化學命名法 無機化學命名法 元素系統命名法 輪烷命名法

答2
維生素C又稱L-抗壞血酸 Ascorbic acid
IUPAC名稱: 3-氧代-L-古洛糖酸內酯
L-(+)-抗壞血酸

2007-09-02 20:23:21 · 1 個解答 · 發問者 Anonymous

2.0g的固體二元酸H2A溶於水,制成250cm3的溶液。然後把25cm3的溶液與0.1M氨水進行滴定,所需氨水份量31.8cm3。計二元酸的摩爾質量

2007-09-01 11:10:49 · 2 個解答 · 發問者 ? 2

學校的顯微鏡. 在實驗水中的生物之後顯微鏡的物鏡常會粘污.乾掉
留下髒髒的痕跡
下一次觀看顯微鏡會受很大的影響
擦拭顯微鏡的物鏡應該是使用 酒精或二甲苯 ? ? ?
將其滴在拭淨紙上擦拭. 繞圈圈狀擦拭

2007-09-01 05:49:17 · 2 個解答 · 發問者 lionliou 2

1.開油水
2.銀紅色油漆
3.啞黑色油漆
4.PU 稀釋劑
5.電鍍透明色油漆
6.PU面漆硬化劑

2007-08-31 11:53:09 · 2 個解答 · 發問者 NELSON 1

50cm3 of a solution of I2 in CCl4 were mixed and shaken with 50cm3 of H2O in a separating funnel until equilibrium was attained. If 50cm3 of H2O contain some dissolved KI, will this affect the value of the partition coefficient? The suggested answer is: No, the value of Kp is only temperature dependent.

But I think if the H2O contains some dissolved KI , it will react with I2 added to give I3- and this reduce the [free I2] in water, resulting in decrease in Kp. Why am I wrong?

2007-08-29 10:21:50 · 1 個解答 · 發問者 ? 2

「水若反覆地一再煲滾，會令水裏一種叫「硝酸鹽」的物質變成有毒的「亞硝酸鹽」。」嘅ionic equation應該要點寫？

2007-08-28 09:56:34 · 3 個解答 · 發問者 ? 4

我知道 滴定果陣 加入水 去沖洗 錐形瓶 唔會影響 留上 滴定既結果
但系 留下變色 果度 多左水 唔會影響變色?

2007-08-27 20:23:04 · 1 個解答 · 發問者 hin 1

苦瓜含有甚麼物質令人覺得苦?
苦瓜有甚麼食用和醫療價值?

2007-08-27 13:11:54 · 5 個解答 · 發問者 Potter 1

解釋:鋅是由閃鋅礦與碳共熱生成。

2007-08-27 10:54:03 · 1 個解答 · 發問者 ? 2

heat什麼metal oxide才會出現metal?
請列埋chemical equation....
heat什麼metal oxide會係no observable change?

2007-08-26 20:24:01 · 3 個解答 · 發問者 Kelly 2

For each element down the Group, the outermost electron which is to be removed is shielded by an extra shell of electrons.

有冇人可以幫手解釋下呢句??
同埋shield呢個字o係chem入面點解??......

thx!!

2007-08-26 18:34:41 · 2 個解答 · 發問者 NewBoy 2

沾有碘化鉀溶液的濾紙是什么顏色?

2007-08-25 20:05:54 · 1 個解答 · 發問者 紫玲 1

當講d subshell果陣......
e.g. 1s1, 2p1

當中既s, p, d, f...個字母既全寫係咩???...

定係冇的???...

呢d字母係根據乜野而訂立出黎既...??

點解要叫s,p,d,f...唔叫a,b,c,d?

2007-08-25 19:06:28 · 1 個解答 · 發問者 NewBoy 2

2.08g of PCl5 are vaporized at 500K in a 0.001m^3 flask. Some dissociation occurs according to the equation PCl5<---->PCl3+Cl2. The partial pressure of Cl2 in the resulting mixture is 20.265kPa.Determine the partial pressures of the other constituents and the total pressure of the mixture. (Relative atomic masses:P:31;Cl:35.5;Universal gas constant=8.314/mol K)

2007-08-24 19:18:09 · 1 個解答 · 發問者 TamTam 7

Two flasks each of equal volume are connected by a tube of negligible volume. Initially both flasks are at 27 C and contains 0.7 mole of hydrogen gas, the pressure being half atmosphere. One of the flasks is then immersed in a hot bath 127C while the other is kept at 27C. Calcilate the final pressure of, and the number of moles of hydrogen gas in each flask.

2007-08-24 19:17:02 · 1 個解答 · 發問者 TamTam 7

當電池消耗晒的時候，會唔會因為入面的Chemical用完而令電池變輕?

2007-08-22 16:28:44 · 3 個解答 · 發問者 Tina 2

2c Determine the mass of a one-trillion (1.0x10^12) atom sample of copper.
My ans:1.0x10^12/L x 63.5 = 1.05 x10^-10g
The answer from the book = 1.08x10^-11g

3e Calculate the number of e- contained in 2.8g of nitrogen gas
My ans: 2.8/28xLx2x5(as each N atom 5e-)=6.022x10^23
The answer from the book =8.43x10^23

from comprehensive
plz help
3q

2007-08-22 15:10:24 · 1 個解答 · 發問者 2003 2

Question from 06' CHem AL pastpaper paper 1

Q 6(c) (i) Mutiple choice

Which of the following compound has a pair of enantiomers?
(I am sorry that I can't draw their structures here)

My question no1: Why the answer is B? How can we determine?
My question no2: How can we name the compound in choice B (IUPAC) ?

2007-08-22 11:47:40 · 1 個解答 · 發問者 ? 2

我們照著之前某個大大所說的做了實驗
可是無法發出電

他說:
1.先取電池裡的碳棒(就把一號廢電池拆開 裡面就有了 用水把他洗乾淨)

2.用飽和食鹽水把衛生紙用濕

3.用上述的衛生紙把碳棒包起來(兩端要有0.5公分碳棒露出來)

4.再用鋁箔包起來(比衛生紙的寬度少一點) 就完成了

碳棒為正極 鋁箔為負極
碳棒與鋁箔的正負離子互相跑來跑去 就有電流了

請問這個方法真的會發電嗎~~~拜託唷
急需要答案~~~實驗要用到
因為我們剛做過ㄧ次發現沒有電ˊ ˋ不知是哪裡出問題

2007-08-22 08:41:03 · 3 個解答 · 發問者 Brian 1

an egg in vingear
what kinds of chemical is the egg shell made of?

what kind of a chemical is vingear?

whaat will happened when the chemical in egg shell and that in vingear come together?

An egg in vingear
List some possible factors that can make the changes described take place faster??

2007-08-22 08:32:25 · 1 個解答 · 發問者 kaming 4

為什麼燒唔同的金屬，火會有不同的顏色？

2007-08-22 07:04:23 · 2 個解答 · 發問者 C14 7

請問由Calcium Sulphate 生產 Sulphuric Acid, 中間需要什麼程序? 工業上可行嗎?

2007-08-22 05:26:09 · 2 個解答 · 發問者 bwkchang 7

Concentration of sodium carbonate solution=0.105M
Volume of each aliquot of sodium carbonate= 20.00mL
Recorded titres of hydrochloric acid (1)12.75mL (2)12.45mL (3)12.39mL (4)12.40mL
d)Calculate the number of mole of sodium carbonate in each aliquot
e)Using the mole ratio calculate the numbers of mole of hydrochloric acid in the average titre.
f)Therefore calculate the concentration of the acid.

2007-08-21 17:07:50 · 1 個解答 · 發問者 hingwood 1

A standard solution of sodium carbonate is used to to find the concentration of some hydrochloric acid. 20.00mL aliquots of the sodium carbonate are pipetted into conical flasks and titrated against the acid using methyl orange as indicator.

ii) Would these actions affect their final result?
Adding 10 drops of indicator instead of 3 drops
Using a wet conical flask instead of a dry one?

2007-08-21 16:39:53 · 1 個解答 · 發問者 hingwood 1

眾所周知,在金屬活潑序中,銅及以下的金屬不能與冷酸反應。但他們能否與熱酸發生反應呢?

2007-08-20 15:43:58 · 1 個解答 · 發問者 還不明白的薑 3

點解bleaching action of chlorine water is due HOCl
but we can't say hypochlorite ions?
點解hypochlorite ion 許chlorine bleach就係active ingredient?
但係 HOCl <--> H+ +OCl-
OCI-許呢度就inactive 左?

2007-08-19 18:10:36 · 1 個解答 · 發問者 2003 2

2.65g of anhydrous sodium carbonate was dissolved in water made up to 250.0 cm^3 solution 25.0 cm^3 of this solution required 26.3 cm^3 of a hydrochloric acid soltion for complete neutralization . Find the molarity of the hydrochloric acid.

2007-08-19 14:25:01 · 2 個解答 · 發問者 guaeiogaeighi 1

因為條牛仔褲著到軟哂, 聽人講用未稀釋醋酸浸48小時再風乾, 就可以變番硬, 但係我條牛仔褲本身係染左色, 甘會唔會甩色嫁? 唔該哂......

2007-08-19 09:20:49 · 2 個解答 · 發問者 HONG 2