真四第張六第日七初月正年巳丁馨蔓
1977中學會考試題預習專欄
明德社主編
化學(十六) ·朱宏林·
Che:istry (16)
Answer to il: 25
a) A is propan-l-nl, Chou, Ch 011;
9 is propanoic Fcid,
C is sodium propenocte,.
is ethane,
C
E is prop-l-ene, CR,CH=CH2. The two other compounds are
CH,CHCH,propan-2-01
and
OH
CHCOCH, methyl-ethyl ether Acidified potassium dichromate is added in (1); and acidified notresium permanga- hte is used in (i) as it is much stronger,
d) Soda lime is the quickline or calcium hydroxid slaked with. sodium hydroxide.
e) Concentrated sulphuric acid is
used for dehydrating the propan-1-ol to prop-1-ene.
f) 1) 201 ̧CH C0011 + 2ña
2CH CHICOONa+#2 + Hách
CH2CH
ii) CH-CH2cocra
iii) CH CT CH2O
The reddish-brown colour of bromine vapour disappears as they react to form an addition compound which is colourlers.
CH2C=012+Br2CH_CIBгCHST
The product is called 1,2-31- bromoprop ne hinc is an oily. liquid.
h) The heated, comper acts as an
oxidizing agent converting prown-1-ol to propanal. i)he product is mainly provyl
propanoate, CCIL COOCE C12CH3..
•Cl2 CCOO + CH
Answer to
A.
a) The backward reaction is
e-dothermic as the forward reaction is exothermic.. b)... of rethanol = 32
ccording to the riven equa- tion, 9.2 kJ will be libera- ted in obtaining 32 g CH2OH.
the energy change in pre- paring 16 g methanol is
16
9.2 x KJ =
32
4.6 kJ
the energy is evolved in the form of heat,
c) White fumes are observed which
is moist hydrogen chloride.
The products are chlorome thane- (or methyl chloride), posp- horus oxychloride and hydrogen chloride.
►CH3C1+ FCC13 +[C]
It is to boil the ester with water to which a little of mineral acid is added. b) It is because caustic soda
can reset with any ethanoic acid liberated to form sodium etanoate, thus shifting the equilibrium position to the right. This process is more com only known as saponifica- tion. The producats are
ethanol and sodium ethanoate.
+ NaOH
c) CH2000C5
C10+ CH3COONA
a) he reaction equation is,
CIL OCCA
2
CHOCOR +3ital
CE2O!
WAH KIU YAT PO
The observed facts can be ex- plained by hydrolysis of salts which can be regarded as the reverse of neutralisation,
i) KCl is not hydrolysed by
water as it can be prepared from the action of a strong alkali, NaOH, and a strong acid, 01.
ii) Fa,C0, is obtained by re-
action be a strong
alkali,
ani a veak
acid, CO. So, it can be hydrolysed by wter and the resulting solution is alaline. CO.
lii) 1 is obtained by re- action between weak alk- ali, l, and strong acid, 4:01. So, it can be hydrolysed by w ter and the resulting solution is acid.
MICH WH CL+H20 HC1 + MY CH (more precisely, the reaction
can be represented by the Following ionic equations:
Gog 2+2H2011 +2 CO
NH
+ 720 — 130* + 1}z
Answer to 2.27
a Concentrated hydrochloric acid
is run into flask A.
b) It is because potassium per-
manganate can oxidize cone HC1 to chlorine in cold.
c) Conc 11,30, is used to dry the
chlorine gas.
d) The equation is
2Fe(s) + 3C1, (g) →→ 2FeC1, (s) e) i) It is because chlorine is poisonous and very reactive, attacking our noses and lungs. ii) It would be much better: to carry out the experiment in a fume cupboard.
iii) This could be detected by using a wet blue litmus paper which would be changed to red: at first and finally bleached white by the escaping chlorine. This is because chlorine is a very strong oxidising agent, so when it reacts with iron, it oxidises iron to its high- est oxidation state and so, only iron(III) chloride is obtained.
6) Iron(II)chloride is formed. It
is because hydroren chloride. is a reducing agent, so the ohloride of iron in lower oxidation state is formed, h) i) The yellow colour is due
to the dr ted iron(III) ion. ii) The pil would be smaller than 7. This is due to the hydrolysis of iron(II) chlor ide to rive insoluble iron (ITI)hydroxide and hydrochlp-
ric acid.
FeCl3+340 — Fe (01)z
+3HCL
i) Relative mass of iron 56.
Formula mass of iron(III) chloride - 56 + 3 x 35.5.
162.5
According to the equation in (a), 3 moles of C1, reacts with 2 moles of Fe to give
2 moles of FeCl3+
(1)nss of iron used up is
0.5 x 23 x 56-8 18.7 €
(ii) mass of Fell, formed is
x162.5 e
0.5 x
3
54.17 €
Correction for Chen(15)
3.26 (c) should read as follows: Write n equation for the
reaction btwee the ester,
CC0025, and caustic soda.
as mentioned in (b)
物理 (十六)·魯榮家
報日僑華
四期星
Apply the lens formula. (Real is +ve)
+
*
duct PV is a constant. Hence
35X200 70X100 = 140X50.
7000 constant.
Therefore. for pressures-
1
35mmHg to 140mmHg, Doyles' Law applies.
ii) Apply the Boyle's Law
(A)(70) = 7000
A100mm Hg iii) 154mmHg 184mmHg in-
dicates the gas sa-. trúated with water vabour for the Boyle's Law fails to apply.
i
Apply the Boyles' Law:
PM constant
Let h be the length of the water column.
A be the cross-sectional area of the cylinder.
1
ve
-750mmHa
- 900mmHg
= 2A
1
=
(2-4)A 720X2A
h = 0.4m
900x(2–h) A
(Ans.)
ii) Difference of the
Pressure readings. 720mmHg
00mmHg
180mmHg
ressure due to water column of Hm height. Also, 180m/nHa
=0.18m4α
= 0.18X13.6xPxC.
Where is the density of water.
0.18x13.6xPx = PGH
H = 13.6 x 0.18 2.448m.
Depth of the lake. 2.448m + 0.4m 2.848m
日四十月二年七七九一服公年六十六國民鍥中 青教僑
= 58 - CA*
0-37m - 0.33m
= 0.04m.
A = wave length).
Constructive interference
occurs at .
=
0.2m
b) Since F = 0.2 hence u 0.24
ii)
0.24
+
1.2m
=
(Ans.).
B
(Ans.)
ii) rath difference
QA QB
The position of the image is 1.2m behind the lens. magnification = .245
size of the image
5 x 40mm
200mm
0.2m
(Ans.)
If a plane mirror is in- serted 0.4m behind the convex lens, then,
04m
0.4m
M=12M
As figure shown, the image fourned by the convex lens before the plane mirror is inverted is Iq
0.24m, f=
0.05m 0.05 0.04
1.25X
(Ans.)
c) Since f
24
Where L = length of the
vire
tension of the
vire
mass per unit length of the wire
Hence, the tension of wire is the weight of the block. When the block is in air.
-(1)
2X1
where W is the weight of the block in air. When the block is submerged. in water.
f =
2 X 0.9
Where w' is the weight of block in water.
0.24 0.2
V
1
Since. +
(Ans.).
1.2m (i,e,result of
(i))
1 against
Hence magnificationm,
1-2
0.
c) Let the depth of the pool
beth. metres, the density of water bef.
=Pressure at the bot--
tom of the lake. 750mmHg + @@H. 0.75X13.6xPg+pg h (10.2+h) pg.
= volume of the air
bubble at the bottom
3
= 9.52X10-6 Ti
temperature of the Pool at the bottom- temperature of water at surface- temperature decreas- ed due to temperature rradrent, 127-4)°C (300).
ressure at the sur- face 0.75x13.6 g. -63 3.02x10 27°C 300K Apply the gas law:
PV. 11
(10.2+h)pax9.52×10-6 (300-h)
0.75x13.6pgx3-02x10 300
. h. #70.4
2.a)
Then when the mirror is in- serted,
hence u
1.2-0.4m=0.8m
the magnification due to Plane mirror 3 The result is the Image I
·But.
13
is the image of I
through the lens.
Hencé object distance is the distance between 12
I and the
lens, since. I is the image.
12
formed by the plane mirror, therefore. ::
= 0.4m 0.2m
+
(virtual object).
(Ans.)
is Bositive which Since indicates the final image is a real image.
M3
3
is
straight line with. intercepts (0,1) and
(7,0), Prom the graoh
}
- 5
(Ans)
ii) uv 0.25 0.16 0.165 0.205
uv
0.25 0.16 0.165 0.205 0.25 + 25 0.8. 0.83 0.8231.25
0.4
1- 3
since
+
The position of the final image is
in front of
the lens the size of the final image/
= 40mm x my
X
=40 X 5 X 1 X
663mm
0.0666m
a)
(Ans.)
As figure shown, the rays from the object must have been incident on the mirro normally so that the image
coinside..
1
M
200
=
(Ans.)
4.0 2.5 2.0
1.0 2.5 3.0
0-2 (U+V)
uv
uv = £{u+v)
Therefore av against (u+v) is a straight line with slope f.
As the Figure shown,
the slope =
= 0.2m (ans.) Ans
f=
1-3331.0 From(1)
3.663 4.0
Fron(2)
1 / 35
W = 4 fu
W*= 4(0.9)2fu
Loss of weight of the
block when submerged in water
- W - W
-4F- 4(0.9)2 Eu
= 0.76 fu
Relative density of the block
W
- A
4fu
0.76fu.
5.2631
Density of the block 5.263X1000kg/m3
= 5263 kg/m3
(Ans.)
10.36m| →→→
2X0.25.-
Suppose there is no morror. herice
'PÅ
0 薯 b) i As figure
A'
2
3.
5
shown,
rath difference
i
ww
V =
0.1m+2X0.25m -8:36, 1=0.6m.
-B FA
,
I
e) The products are
CHOU CH2CH
+ 3RCCCNa
Physics (16)
lycerol and 1) According to Boyles Law,
sodium alkanoate; the latter
is what we call is scap.
時今的官
有此,在之
大對較
1.a)
if the temperaturè is
held constant,
the Pro-
並養費備過程中,就同一學生會之報常與活動,
望燾此全面介纇理工 - |殺璠工學院之結構,及 六,及廿七日舉行,八二院校成人 1!瑭工開放日將於卄理工學院發毀的關係, HHIASCHENB <RREHEGNEK - (ES)BRER (1)*~
理工學生會主辦 二届理工開放日 本星期六日分兩天舉行
#敎育當局之現行政策 汝約殛一百二十間。根 意見。 卽未參加「置位∫計劃「價位3計劃事 - 提供 ,其中未獲政府派位(平時期去函數育可,就 私立中學二百六十餘間應,英文校聯會做於曹 〔被凯》本祜現存一局至今未就此事作出反
時候。在地狹人多的香 間爲星期一至星期五上。
·警地方,肝臟室開放時一等濶座,詳將公佈
·閲讀之用,以提供谳與你」,「升學就業 三月一日起開放中心作於三月開始舉辦「书拭 蓀,一般學生均缺乏寧屆中學會考及畢業生 靜的溫習環境 - 特定由一付考試及就業問題 - 將
業努力,準備應付考試準彌。 ,又是全迷果生開始調「訓室,爲考試作出R分 握新年過後,三月開始於上述時間往中心開
·國大厦十五樓),以是一時正,歡迎區內學生 | 愛中心冖毓道中安樂 星期六上午十時至下午 (新豐社 中盛明 午十時至下午六時正, 核中心又爲協助调
英校聯會就「買位」事 去函教育當局提意見
外,更有多項恩施,包一想。 放校舍 - 工塲及實驗室| 學行,歡迎各界人
中區明愛中心
-三月一日起開放
供學生溫習功課
社會的關係,屆時除開|11月廿六日中午十二脚
;政府日計劃於一九七
‘農會函件大路推出
中國婦女會丘佐榮校 家庭生活教育研討會
當局交沙召年教育當’家有更多選擇。 校邪會會就此事與教育 校參加升中試派位,將
·大顾氰。香港私立英文一大,此外,吸收更多學 此畢勢必造成教育界之支出,於行動亦影响不 披切斷中一學生來源,劃,將不致增加當局之 °F 學校網 ∫ 之外 - 從而 收更多學校參加其位計 此一百二十間學校,七年升中試派位中 因一九七八年將被拒於 從多之學位 - 因此,吸
廿七日舉行主題「子女教養」 核音樂親鬻大會的
(E),
星期日八十七)-下午間奔蹈及樂器演在等。
嬌女會丘佐榮學校 - 定 黴泪有歌唱、明师、民
時至五時在該校禮堂
以專題演噐〔由校長
任和合作 - 国降將分別飾
之聯繫,以便幫助子女
及加強學校與家庭之間
可能深入了解其千女,
·宿里赫,目的希望家長
宄等形式介紹主題。甘
查面女間,機長據
會學理地杈
聯
外皮
時
於明
演此動,
的 的社 章助 烷氧
部 騶鷹 舜有 區的
編並的、許地主角
四術友會耀理學高會校灣目 將覽 香港 區辦。民的
̇欸
籌影電七廿委輪
*** A
學之對聯的對 港 校學校絡興我撕學
DAX
,有較完善之發發。勤十二。自成立以來,
萬人音樂大會
“長出席云。 討會,做迎該校各生家
·今南華會暴行
塲出席一個萬人音樂廳門券可於當日上午在航 時,在加路連山南華會及精乳牛班的 的一萬四千名學生將於一集本年度的活動經費如 今(星期四)天下午一地週邊區,池通海家大
丸,至多於11月1十七 ERKNEE-BKE ORIS - 846EN 果名胺改楬「新维樓的 黑獄,上映由大交聯 RES AKIREE DE
BERLARSCIE 上午十時半,猳座九龍 日(星期日年初十),
〔港 來自多
官立、津貼及私立學校醜」,門要分金元,大
*K*•
壓門
將不
No comments yet.
Private notes are available after approval.