Chemistry 化學 (高級)

教你分Enantiomer / identical  學識以後100% 對
呢家見好多人都分錯兩隻compound係enantiomer 定identical，有時簡單既大家可能好快就分得出，但遇上難既，可能會分好耐，所以教大家一個秘訣，只要學識左，就可以好快好準確甘分得出係邊隻。    點擊
入考場之前一定要識背既ppt表
相信温得熟既同學都知道下面個表係乜，大家係考試之前記得背熟個表，先分到邊隻ionic compound 係soluble，邊隻係insoluble。粗略估計，每年起碼有10-20分直接/間接考核下面個表，所以大家千其唔好睇少佢！！       點擊
Unit 1 Planet Earth and The Microscopic World and Metal (微觀世界+金屬)
1.        The most abundant element in the world is oxygen and the most abundant metal in the world is aluminium
地球上最豐富的元素是氧，最豐富的金屬是鋁

2.        The chemical nature of lime water is Ca(OH)2
石灰水的化學本質是Ca(OH)2

3.        Flame test is not a test for metal but metal ion. For example, golden yellow flame can be observed when NaCl is burning. When sodium is burning, metal Na turn to Na2O and Na+ in Na2O give golden yellow color

焰色測試是測試金屬離子而不是金屬，例如燃燒 NaCl，可以看見金黃色火焰。燃燒Na 時，金屬Na 轉為Na2O，Na2O裡的Na+ 把火焰轉為黃色


4.        The "molar mass" of air is around 29 g mol-1 which can be obtain by following formula

molar mass of air = N2 x 78% + O2 x 21% = 28.56 g mol-1

If the molar mass of a gas is smaller than air, it density is lower than air and we should use an suitable method to collect the gas.

空氣的「摩爾質量數」大約是 29 g mol-1，是這樣計算出來的

空氣的「摩爾質量數」     =    N2 x 78% + O2 x 21%
=    28.56 g mol-1

如果某種氣體的摩爾質量數比空氣細，它的密度比空氣低，知道這點有助我們選取適合的氣體收集方法。
(Others coming soon =) )



Unit 2A Acid and Base (酸和鹽基)
1.        Concentrated H2SO4 is corrosive since it will dehtdrate our skin and damage our skin by oxidation.
濃H2SO4是腐食性的，因為它會把我們的皮膚脫水，而它的氧化性會破壞我們的皮膚。
(1997 Q39)


2.        Strength of acid depend on its degree of dissociation into ion but not its concentration.
酸的強度取決於它離解生成氫離子的能力，而非濃度
(1996 Q49)


3.        All the oxide, hydroixde, carbonate are insoluble except group I element such as Na2O, K2O, Li2O as well as NH4+
所有氧化物、氫氧化物、碳酸化物都是不溶於水，除了第一族的金屬元素離子和銨離子外。
例如Na2O, K2O, Li2O 和 NH4+


4.        HNO3 has rather low boiling point around 90℃. So HNO3 is volatile.
Also nitric acid react with metal by redox reation but not typical acid reaction. 
2HNO3 + 2H+ + Zn → NO2 + H2O + Zn2+
As you can see from the equation, NO2 instead of H2 is produced in the reaction.

HNO3 的沸點大約在90℃，所以它是揮發性的。HNO3也會和金屬反應，不過是氧化還原反應，而非一般酸和金屬的反應。從上面的方程式可見，NO2 在反應中產生了，而非H2

(Others coming soon =) )





Unit 2B Redox Reaction (氧化還原反應)
Unit 2C The Microscopic World (微觀世界 II )

Unit 3A Fossil Fuels and Carbon Compunds (化石燃料和碳化合物 )

1.        Warm house gas include CO2, CH4, CCl2F, NO and O3.
温室氣體有CO2, CH4, CCl2F, NO and O3.

2.        Polystyrene is a packing material
聚苯乙烯是一種包裝物料
(98Q36)

36. Which statements concerning polystyrene is/are correct?

(1) It is a condensation polymer.
(2) It can be remoulded.
(3) It can be used to make packaging material for electrical appliances.

A.   (1) only.
B.   (2) only.
C.   (1) and (3) only
D.   (2) and (3) only 
                                                                                               ANS: D


3.        Leaded petrol is being banned in Hong Kong
含鉛汽油在香港是被禁止的


1998          
47.         statement 1
The use of leaded petrol has been banned in Hong Kong

statement 2
Lead compounds in car exhaust can cause damage to human brains.
                                                                                                                          AND: B
 (98Q47)

4.        Hard water is a water containing Ca2+, Mg2+. They will form ppt with anion of detergent.
硬水含有Ca2+，Mg2+。它們與洗滌劑的陰離子反應產物沉澱物。


29. Which of the following substances is/are responsible for the hardness of water?

(1) Sodium chloride.
(2) Calcium chloride.
(3) Potassium chloride.
(4) Magnesium chloride.

A.   (1) only.
B.   (2) only.
C.   (1) and (3) only
D.   (2) and (4) only
                                                                                                        ANS: D
(Others coming soon =) )

Unit 3B Organic Chemistry (有機化學)