REFERE
24 JAN1973
*** FEMA) F-##=+#JIRI WANTNU HALPO
1973英文中學會考試題預習專欄,
化學科
(十四):
semisury (4)
Solution for last week Part
மட்கம்
BIOCH
0 T
(a) 1) When we heat a hydrated salt to drive out the water crystallisation, do not heat it too strangly, because man, hydrated salts decompose unde strong heating.
(b)
11). When we heat a liquid in the test-tube, it should be kept in constant movement in the flame so that it is heate uniformly. The mouth of the test-tube should always be pointed away from anybody just In case the chemical way shoot out under heating.
When ammonium hydroxide (0 solution is added drop, by drop to copper sulphate solution, first, a pale blue precipitate is fomed. Then the precipitat is dissolved in the excess of ammonium hydroxide solution and the colour" bècomes trans- parently deep-blue.
(c) The lead nitrate decomposes
giving off brown fume, lead oxide remains.
2Pb (NO3),– 2pb0: 4NO2+
(1) Direct combination: Salts which contain only two elements can be prepared direct ly from the elements concerned. 2Na+ Cl
2NaC.
(ii) Displacement:
This is normally used for metals. above hydrogen in the electro chemical series.
Zn + H2SO
ZnSO
(111) Neutralization:
This is a reaction between an acid and a base
HOL+ NaOH
→ Naul + H20
(v) Double decomposition: Insoluble salts are best prepar ed by a double decomposition reaction between solutions of two soluble salts or between a solution of a soluble salt and an acid
Pb(NO3)2 + H2S04 →→→Pbso
7. Solutions and Flames
State of matter
2HNO
zur Water, then, can exis either a solid, liquid or vapour, The changes taking place in this cycle, with the names usually given to each change, are summaris -ed as follows.
Melting
Ice
Water
Freezing
Stepm
Boiling
condensity Some substances when heated 21 a test tube pass into vapour which. condenses again in the cool part of the tube. This is called subli- mation
Solution
A solution is a nomogeneous molecular mixture of two or more. substances, in which one substance is in noticeably greater proport-
on than the other.
If we have a solution consist- ing of a mixture of two substances the substance in greater proport- ion is called the solvent, while the other is called the solute.
Following are some common solvento A
that must be menorized:
Solvent
Water
Alcohol
Carbon disulphide
Solute
Sugar, salts
etc. Iodine
sulphur, phosph -ÒTUB paint, oil
Rubber
Gums
Turpentine
Benzene
Toluene
Jarbon:
Grease,
Fats
Ether, chlorofo
Mercury
Many metals
tetrachloriqu
A saturated solution of a
報日橋
solute at a particular temperature
is one which contains as much
solute as it can dissolve at that temperature, in the presence of the crystals of the solute.
A supersaturated solution e solution which contains more of the solute than it can hold at the temperature in the presence of the crystals of the solute...
Solutions can be classified in the following manner:
1) solutions of gases in gases,
e.g. air.
solutions of gases in liquids, eg. ammonia dissolved in water
3) solutions of liquids in Liquidi
e.g. water and alcohol.
4) solutions of solids in liquids,
e.g. sugar dissolved in water. 5) solution of gas in solids,
eg. Hydrogen dissolved in pallodium
6) solution of solide in solids. e.g. Brass and all alloys Suspensions';
A suspension is a liquid con- taining small particles of solid which are
throughout it and which
on standing.
The ces between
solutions and suspensions can be summarised as follows:
Solution
1. No visible particles of
2.
icles do not settle out to the bottom. of the solution.
3. particles of solute cannot be separated from the solvent by s process of fil- tration..
4. Solid added to a liquid in which it is soluble.
5. Solute or dissolved solia
can only be
recovered by
evaporation.
Suspension visible partí- cles of solids.
particles fall to the bottom of the suspen sion
particles can be separated from liquid by filtration,
Solid added to a liquid in which it is in- soluble
Solubility and Solubility curves
The solubility is the number.
of grams of solute dissolved by 100 grams of solvent at a given temperature is presence of excess: of solute.
Solubility depends: (1) on the chemical characters of the solute and solvent; (2) on the temperat- ure, generally but not always increasing with rise of temperat- ure; (3) on the pressure.
The way in which solubility- depends on temperature, is most conveniently represented graphic- ally by means of solunility: curves in which solubilities are plotted against temperatures. For example, the following figure shows the solubility curves o potassium nitrate and sodium chloride in water at different: temperatures
Separation precess
1. Filtration is a process of separating a liquid and a solid in suspension, The substance re- maining on the filter paper is called the residue and the liquid passing through the filter paper is called the filtrate..
2. Crystallisation is the process of forming crystals by lowering the temperature of a saturated solution, which used to recover the solute from a solution. 3. Distillation is the process boiling a liquid to form vapour and then cooling the vapour to obtain the liquid, which used to
三期星
recover the solvent 1rom a BOLUG ion.
4. Fractional distillation is the process of separating two liquids by distillation, the distillate being collected in fractions boil ing at different temperatures.
5. Fractional crystallisation is the process of separating, two or more solutes by crystallisation, making use of their different solubilities in the same solvent. Flames
A flame is burning gases that give out heat and light.
Candlé flame:
In the candle flame, we are able to observe four distinct Zonés:
日四廿月一年三七九一圈公年二十六國民華中
(a) A dark region just above buc wick. This contains unburnt vapor. of the hydrocarbons of which the candle is made.
(U) A hightly luminous regions ir which the hydrocarbons are decom- posed; the carbon particles so fomed are made incandescent, and the light they emit is the chief light of candle flame
(c) An almost invisible region surrounding the luminous part or the flame. Here the carbon and nydrogen released by the decompos- ition of the hydrocarbons are burnt away to form water and carbon li oxide
A blue region plow une when which is particularly hot, The upward air currents produced by the flame ensure that there is copious supply of fresh unused at this point and so there is
omplete combustion of the hydro- parbons.
ne Bunsen flame:
Non-luminous flame (Air holes
pen)
When the holes are open, air inters the tube and mixes with th coal gas. The gas therefore burns more quickly and completely. We can distinguish three distinct
ones:
An inner zone or cool. unburnt gas.
3. A green or blue middle zone.
The coal gas burns in this zon but not completely,
there is not enounecare?
CHA
2CH
30,
2H,C
CO
4H20 + 200
A pale blue outer zone. In thi zone the burning of the coal gas becomes complete 200+00
200
Hi) Luminous liame (Alr noles closed)
When one holes are closed azic no air enters the tube, the flame is large and bright. The four zones of the flame as follows: 4. A dark inner zone of cool.
anburnt gas.
A luminous yellow zone. The coal gas burns in this zone but not completely as there is not enough air. Tiny particles of solid carbon form.
CHA
+
724,0 + CV
A thin outer zone. In this zone the Coal-gas burns completely. blue zone at the bottom of the flame. This part receives plenty of air because the air dear the flame rises rapidly,
Exercise Part II
What is meant by:-
a saturated solution the solubility of a salt.
(接第六張第二頁)
1978-
中文中學會考試題預習專欄 中國歷史科(十四)・會一民、
2.湖→加丁役宁鸿常次巡務俘政府听役二十日。遇混年加 二日 不役,收其情,每部门三尺。又加役三十日
3.
辦下口稅),各各鄉原出,起了須繳或楼二 丈棉三班。
(乙)做頸目門韧择“和田」以來,顾宮-
足,如此做 之好處,以与锻單位,不能海理,我們之病,而且請提 田則有色,有全則行情,不問有關。借來史能後,卢口散头, 此個無銀行,但院時該用兩條筒na.
中國歷史科預習題.
HIL: SELAM—— 永樂大典,探何帝之女治化錢;
(A)曆大宗
BYGN
(C)阴太明
(D)期成雞.
CE)柴大組
我和你們,事問計誌,何三份的是,並招辦三十餘國。所謂
3.74708
(B) (2) (3) (4).
1.蘇門不朧2踼廠
42.
5.
(A)(1):62)(3)
(C)(3)(4) (5);
CE)(1) (3). (5) ""
造成土保之役的宦官是
(A)WEE
(C)驹照
(E)馬永成
(D) (1) (4) (5)
(B)田區
(D) ZET
14.明大熊王守仁,今贬頭貴州銀場,與何宦官有關?
(A)
(E)吉祥 15.下列向人非日代之宦官。
KAMBE
(c)
(B)魏思E
(D)ZEM
(B)费者 DE
16、蟹、明兩代袞亡之因案相近者爲:(1972年會考試題?
1:榮激料
3-君主武
5.宦官機機
(A)(1) (2) (5).
(C) (1) (3) (5)
(E) (2) (4) (5)
REKHE
4.地方割够
(B)(1) (3)(CA):
(D) (2) (3) (4)
明代皇宫其之獎,始自何者靜技?
GAYER
(C)
(E)宗:
(B)武宗
∵飞响明空之衰亡,下列同事最有讯2
、1.王漿、汪南、魏忠賢等宦官弄櫃
2.東永發與非甫黨之爭
8.倭老街入沿港爲您
4. COMES $30THUIZEN
逛感天災服
CA) (1) (2) (3) (4)
99888 83
XB2012 (3) (4)(5);
下列何項是英宗在位年健事簿
1.土木继之役
2.宦官王城解機
3.除去太祖禁食官風政之鐵牌 5.体积出使四我
((((A) (1) (2) (3)
(0)(3)(4)(5)) (B)(1) (2) (5) UZ49, 45;
(A)英宗 CDOBR 蜜案:
(B) (E)玄宗
(B)(2) (3) (47
(D) (1) (2) (4)
宗
(五)唐代府兵制之組織內容如何?有何僅點?供論述之。 (六) 医略進科制度 由來及香代科舉制配的內容 (七)試述麽太宗之對外政策及其露大武功。 (八)班代外交源專案如何?在交化及商業上有何能要影响?
30 gm. of hot solution containing
gm. of the salt begins to cry- tallise at 35°C. What is the solubility of the salt at this temperatura?
The solubilities of potassiu chloride and nitrate in gran of the salt per 100 gm. of water.
.CO)
ксе
270
370 40:0 434 WJ 6.3
(a) What 18 the temperature where both KOL and KNO possess the sam solubility?
(b) What is the range or temperal -ure where the chloride is the more soluble?
(c) What is the golubility of the hitrate at 25°C and 550,00
Would
(a) what weignu or crystals be deposited by cooling a saturat- ed solution of the nitrate contain Ling 30 gm. of water from 70°C. to 1000? What percentage is this o the weight of salt originally dissolved?
(e) If a similiar experiment as i in (d) is carried out on the chlor -ide what are the corresponding figures? Which is the more suitabl salt for this type of crystallisat
don?
(ع)
(1) At what temperatures do these alts differ in solubility by 5. g Iitilizing Le chatelier's principle what can you say about the heat of solution of the two Balts?