1991-01-19 — Page 28

師

理科教師應徵

屛道 100 號校

師

及數理科代

122 約見

育教聞新港本日四初月二十年午濙灣要

報日僑華

與華南地區相配合 本港&新聞

的資源,更脚 規劃的己的基礎設施及 史好作出投資决策 9

使雙方能更好用色

樂聲牌微波電子爐

連續五年銷量冠軍

保持香港競爭能力

窗戶。市場變幻莫測, 取代的通往世界市場的 賣是:香港港華南不可. 現在的客觀經濟事

用戶纸迎

校之第

示會在未來

查報告指出 此可見,樂聲牌在微波爐市場上始終受 排微波道九二年的年玼連線第五年冠軍, 根據最新SRH市場調查報告,樂 放高出一倍有多,由

性,經濟自主權才能異

佰心。

分之十七的 故可子盘,跪时消費者對樂聲牌始終校具

年内

華認爲,香港

勞動力等

楊孝華就此問題作專題演講 (特訊】國泰航空東克,珠海等地無數香|徒,不是沒有阻力的。他界有場一脈相通,

六期星一日九十月一(一九九一○年十八國民豪中 ( 26 )

糾紛:似乎香港

走訪東允,在用甚麽名 月可能是由於兩届繳風浪,店 力。去年十月份菜 務,以保持香港競爭的 堂、以甚麽形式,周積,我們覺得如果要

的熱門話題了。有些

...香港阿莱

可否成行”昨

,可分離的互相依賴的開

保,而這個關係,可說

·可否保持其亞洲-

“但沒 問題 滎飛到更高的合作層次是力求積極性地爲 錦渡重说的貨車道堵 到邊境流酞的急速

經有了這樣的組織,集 ,也許不至於現在來

區的利亞影响政策 。我想,假如幾年前已 可以避免「干預」之說

關係,又如實向 的合作,向自己:

前的低治能力。

特别是近日携出 是向對方索取資料,而也成了 但界定清楚,它的功能只發展經濟開 只要把組織的職權 廣東有更大 有了香港政府在九七年一個話題扯上關係?因爲 「干預」的渠道,或者影館地方的關係也和我還 心這是開了一條「中方人放心了。爲法歷中央 明遇風波未完,有 備這阆事,如中央也自 - 尤其是政府官一组已這樣表示,就會更令 首先,在香港方面 近廣東省長回答記者時 一不知中央是否过正舣

表示,並沒有中央要收

解劑

讓五年保

申請

民新街

故始終是消費者首選的 的性能及安全規格,操越用 方改良微波爐的功能外,還非 樂聲牌的製造商松下器

講座介绍外國特快申請 成年子女祈例延期

訪問 華南經濟協進會的構楨

成立一個正

在八十年代

溫了廣東省南部覆

讀者救童助學運動

獲得各界熱烈捐款

是刻不容緩的事

。你迎報名,

翁周月實女士捐壹千元 七七或親臨北角模鑌里五十五號報名。

作爲躪惠是酒捐欸,義學仁風,至足欽佩。 力支持,爲此項善舉,意義深長,功在社會,昨捐助一千大元 翁周月寬女士熱心公 對華日報救童助學運動,整日均大

捷迅貿易公司捐壹千元

單僑日報第卅四屆演为救童助學運動,你昨(十八)棣收到各 界熬心捐歎响高,为名如下:聖保羅男女中學及上、下午小學唸作活動,實助亞多,不遺餘力,昨捐助一千元,其造福下一代與樂善好 施之精神,殊令人感。 捷迅貿易公司,平素熱心公佘,對本報歷年舉辦之救瑗助手建

仟元:MR. DC.COTTERILL世仟伍佰元,我周 余熊氏仟元,天德教止一拼舍掌午元-香港 -捷迅的易公司壹仟元,大基有限公司壹仟元丁

六基有限公司拥壺千元

大基有限公司對社會隔利事業,平素提倡贊助,不遺餘力,特

勤謝先生要任元,梁兆文先生紀念梁畫成先父豐任元,英記茶莊森 捐出售歎一千元,以响镞本報舉辦之救童助學運動,使荷質學生得 業有限公司董仟元,九龍鱗魚商會伍佰元 MS

FRANCIS MA 五佰元,竹林仙馆伍佰元, 竊盛門魚翅海鲜酒家

熱心公益,嘉惠學之精神,殊令人敬佩不已。 遺業 丁国辉先生捐毒千元

HMIR-KIN SHING CONSTRUCTION CO.MER - IND- “孔度睇先生弍佰元,無名氏佰元,沿革茶行壹佰元,梁墻岛女 佰元,梁剧果先生佰元,佑待行米業式佰元,陳百興先生式佰元 HUTTON MEDIA LTO.式佰元,MAS. M. J. CLOUGH 式,林殊分人感裔。

ETD在佰元,步基證券有限公司叁佰元, 莊淑萍小姐式佰元, 至多,不遺餘力 S饼元,洪新發先生伍佰元- WIDACS WORLD TRADE COAT尊先生熱心公待,對本報歷年舉辦之救育助學運動,贊助

JA EMPORIUN LTD. ER-LARK INT'L LTD. SEK-

潘新楚先生,歐陽美琦小姐伍拾元,朱任式拾元。

●客各界行欺救盘助手如用支梁支付,請寫一華僑日報教業助學 持照人一數字摄荷。

亲宅提三千元

午小平捐六千元 日槪捐善欸六千元以作向應, 华劉華日報就童助季運動均 種熱心社會公獄,古道熱腸之

军,太出亭子之精神,宣令人敬佩不已。 喂±本報整体之救蛮助學運動,使濟貧事生得以氆學 本業,平索提倡贊助,不遺餘力,特搭出善欸

上不遺餘力,昨又捐助三千大元,其造码下一代與坐蔷奸道之柄种 「余柏氏熬心公盆,對本報歷年舉辦之炊童助學運,費助至多

止一精会捐叁千元

精舍素來熱心公蒍,對華僑日報救畫助學運動 項蕃年,意的深展,功在社會,作特捐助

钱捐歎的義舉仁風,至足欽佩。

會捐式千元

COTTERILLITBOR FRI LLE心公益,對本報歷年舉 不近除力,昨又捐助一千五百大元

作捐助二千元,其造鷊下一代興樂善好 對本報惬年起辦之教童助學運

殊夺人感奮。 多,不還餘力,昨日捐助一千元,其造鎘下一代與樂善好施之精神 英記茶莊熱心公益,對本報歷年舉辦之救童助學運街,贊助至

力,特捐出蕃;一千元,以前應太裡粱蝣之救會助學運動,使 學生得以攒續學業,其熱心公亞,新珧及子之精神,實令人敬佩不 恆興建築有限公司,對社會福利事業,平素提倡贊助,不遗餘

英記茶莊捐妻千元 龍學業,其慈心公處,嘉惠學子之精神,實令人敬佩不已。 出善欸一于完,以響應本報辦之教蚤助學運動,使清育學生得以繼 台疆利事業,平素提倡贊助,不遺餘力,特捐

恆興建築有限公司捐妻千元

柒兆文先生紀念辊馬歧先父捐壹千元素

捐助一千元,其造船下一代與樂善好施之精

九龍絆魚黏會捐伍百元

精神殊令人感言。 助至蛋;不值餘力,昨日捐助五百元,其造福下一代典樂蓉好治之 九龍鲜魚商會無心公益,對本報歷年奉辦之教會助學運動,挨

竹林仙舘捐伍百元 捐助五百大元,作爲响迷是居捐欺,義舉仁風,至足欽佩 動 應屆均大力支持,詔贯此項善品,意義深長,功在秕,特 MS FRANCIS MA 共來熱心公益,對準後日報救童助學是

JMS FRANCISMA捐伍百元

助至多,不遺餘力,昨捐助五百元,其隔下一代與樂善好施之梢 竹林仙館素熱心公益,對本報赜年華搵之救童助學遇期,質

洪新發先生熟

福臨占魚翅海鲜酒家捐伍百元

,不遘餘力,在狩捐助五百大元,其造耐下一代貝樂 魚翅海鲜酒家熱心公益,對本報產年泰簽之救發動擊連

翌先生捐伍百元

者救直助學还动,大力文

斗敎師

B

Eschematic

SC the

・仕和日期由:

日至七月底。

1991 中學會考預習專欄

明德出版社

MILL & DALE PRESS

2-2 The diagram below is:

set-up for: carrying: put

ony

o electrolysis

electrolyte, Xy

ts, the External Circuit

Conduction et efectricity

Within the Electrolyte.

simple

師壹名,任教

旗山蒲崗村道

追師

令十二週訓練優

電7601978 洽 之名,三月底到

这府所定

Chemistry(16)

W.LAN

substance which cannot conduct

electricity, eg, non-metals,

allows

conductor of electricity

free electrons

through readily withan f

undergoing any chemical changes.

機構

.1.3 A metal

者

歷,有經驗者

Rheosta

Cations

consisting 41

Pb2+

(H+)

CU2+

when th

js closed, the "electrons Begin to flow from the anode to the cathode: through the Cexternal circuit. As a result, the Ccathode becomes negatively charged due to an accumulation of electrons there while the anode, « being deprived of electrons, becomes nositively charged, However, within the molten electrolyte, the positively-charged ions, attracted to the cathode and the negativery-charged ions

are d to the anode. That is

rely-charged

at the positively

why

•called the cations and the 'negatively-changed ions are the /

anions

When the ions reach the electrodes,

, chemical changes. take pigce.

At the cathode, each

each section

an electron from it and besoin.

neutral atom (or radical):

. Thus, the reaction at the cathodegr

' is a reduction reaction.

Aa+

Increasing ease of discharge:

Anions

(b) Relative concentrations of the

fons

Anfon at

higher

concentration is more readily discharged than one at a Tower concentration. Sometimes. the d

concentration

as

r effect " is so great. that it may reverse the order of preferential discharge indicated in the E.C.S.. e.g. in electrolysing conc. NaCl(aq) the chloride: ions fcy are discharged Din preference to the hydroxide: ians (OH) though OH is above Cl the E.C.S..

tof Nature of electrodes

shed nature of the electrodes :hay sometimes affect the choice.

Tof the miles

jons for discharge and. hence the products of electrolysia. For exaiple. Ho

the cathode if NaCl (aq) using

platinum electrode, but Na is ubtained using a mercury. cathode | because Na discharged combines at once with mercury

to form the sodium amalgam.

4. Summary of Results of Electrolysis on Several. Typical Electrolytes mo

ww Name of the substance liberated (Msink Name of Cathode of Anode of

Cat cathode

Remarks

at anode,

Graphite Graphite Lead

Leadi (grey beads) Pb+(aq) + 2e

Bromine

dish

Pb(e)

+4e

(b) Purification

(refinery)

-metals such as copper, lead.

(c) Electroplating.

of

(d) Manufacturing of NaOH, Cl, and HCl(aq) by electrolysing brine solution..

(e) Anodising aluminium.

5.2 Purification of copper

An anode, Cù dissolves to "form cu2+(aq), Teaning behind

Cu(s) - Cu2+(aq) + 2e

2Brak

| axigene

OH(aq) →

:Oxygen.

40H(aq).

Volumic Iratio of

20(2)+0, (9) H2:0, 2:1,

Thus, pure copper is obtained on the cathode.

The object to be electro-plated is made the cathode.

The metal to coat the object is

The electrolyte used is a saturated solutian.containing the corresponding metal jons.

The purpose of this process: 15 mainly to improve.. cand: prevent corrosion.

5.4 Electrolysis of Brine solution.

海學歷及聯絡 箱358 號

EACHER M

ided secondary

h resume, tel. no

Can Hing School,

ng Tau Hom,

督教

力稚園

金照政府建議。

[寶,檀打字,字

照政府建議。

信箱 503號60309

書記

记,中五會考 字,可選擇到 焄寄東院道十

which does not conduct electricity in any state or when dissolved in most covalent

electrolysis of a substance is to

he carried out.

1.8 An electrode is a conductor.

2. Hechanism of Electrolysis

an electrolyte is .fused or

2.1 When ved in, water, the resulting

liquid

would consist of mobile

ions. moving constantly. but f randomly in the liquid.

At the anode, each anion joses its extra electron to the anode and also becomes a neutral:atom for radical) again...

Thus, the reaction at the anode is an oxidation reaction,

This diving af'eléctrons to the the

·cations by the i cathode and

taking of electrons from the anfons by the anode keep the current fiawing in the circuit. The atoms for radicals): discharged at each electrode. may combine with one another to give the more stable forms.

2.3 An electrolytic process is hence 'equivalent to a redox reaction, involving a transfer of electrons from the anions to the cations.

affecting

3. Facunarge of Jons.

Dil Hạnh

·NaCl(aq)

-Oxygen (with:

some Chlorine) ratio of 40H(aq)

Chlorine

Graphite Graphite Hydrogen

2H(aq) + 2e

~H2 (9)

•

2c) (aq)

C12(g)+2e] H:C1D = 1:1,

Conc

`NaCl(aq) (brine)

J Graphitef Sodium.

Chlorine

selective

Na*(aq)*(s)

Platinum Platinum Copper

Oxygen

deposited Cu2+(aq):+287 Cu(s)

Copper

When there are more than one types of cations or anions in a voltameter, usually one of them is -preferentially discharged. Such a selection of fons for discharge ' depends mainly on the following

three factors..

(a) Relative positions of the ions in the Electrochemical Series (E.C.S.).

In general.

the lower the

position of a cation is in the Electrochemical Seri

more:readily it is es. the

̇at the cathode; but, the higher. the position of an avion is, the: more: easily it is discharged at the anode. The reverse is also true. Some of the common ions are listed below according to their relative ease of discharge at the electrodes. If all the other factors are the same, an

are the Sole, ion will be discharged from the solution in preference to those above it in the list.

Cuso,(aq)

Copper

Conc HC1{aq)

Graphite Graphite Hydrogen (or

2H* (aq) + 2e Platinum)

H2(g)

l deposited

Copper dissolved

Cu2+(ag)+28~~ Cu(s)

intensity of blue Icoloration

#Cu2+(aq)+2e. I remains.

Chlorine 201 (aq)

unchanged.

volume:

ratio of

•Cig(g)+2e" ]Hz:Cl2 = 1;1,

concentration

of hydro- Ichloric acid

decreases.

examples are listed, below.

(a) Extraction of reactive metals such as Na from malten NaCl, Al from AlOg.

Na/Hg(2)+2H20(e) ———— NaOH(aq) +H2 (9) · Hand CÌ combines to give

5. Applications of Electrolysis

Industry

in

an important 5.1 Electrolysis 1s

technique and has wide applications Some important in industry.